GM Service Manual Online
For 1990-2009 cars only

Engine Control Module Scan Tool Information 1.6L

Table 1: Engine Control Module Scan Tool Data
Table 2: Engine Control Module (ECM) Scan Tool Output Controls

The Engine Control Module Scan Tool Data List contains all engine-related parameters that are available on the scan tool. This is a master list arranged in alphabetical order and not all the parameters listed are in every engine platform.

Use the Engine Scan Tool Data List only after the following is determined:

    • The Diagnostic System Check - Vehicle is completed.
    • No diagnostic trouble codes (DTCs)
    • On-board diagnostics are functioning properly

The scan tool values from a properly running engine may be used for comparison with the engine you are diagnosing. The Engine Scan Tool Data List represents values that would be seen on a normally running engine.

Important: A scan tool that displays faulty data should not be used. The scan tool concern should be reported to the manufacturer. Use of a faulty scan tool can result in misdiagnosis and unnecessary parts replacement.

Only the parameters listed below are referenced in this service manual for use in diagnosis.

Engine Control Module Scan Tool Data

Parameter

System State

Expected Value

Description

Base Operating Conditions: Engine Idling/Radiator Hose Hot/Park or Neutral/Closed Loop

A/C Evap. Temperature Sensor

--

-40° to +130°C (-40° to +266°°F)

This parameter displays the temperature of the A/C evaporator core based on the input to the control module from the A/C evaporator temperature sensor signal circuit.

A/C High Side Pressure

A/C OFF

0-5 Volts

This parameter displays the voltage from the A/C high side pressure sensor signal circuit to the control module.

A/C ON

0-5 Volts

A/C High Side Pressure

A/C OFF

500-2,200 kPa (72-319 psi)

This parameter displays the pressure from the A/C high side pressure sensor signal circuit to the control module.

A/C ON

300-1,200 kPa (43-174 psi)

A/C Relay Command

A/C ON

On

This parameter displays the state of the air conditioning (A/C) clutch relay control circuit as commanded by the control module.

A/C Request Signal

A/C ON

Yes

This parameter displays the state of the A/C request input to the control module from the heating, ventilation, and air conditioning (HVAC) controls.

BARO

--

65-104 kPa (8-16 psi) - Varies with altitude

This parameter displays the barometric pressure. The control module uses the barometric pressure sensor input for fuel control to compensate for altitude differences.

Case Diagnostic Learning

--

Learned

This parameter displays Learned if the control module has completed the CKP System Variation Learn Procedure.

CASE Learned Cyl. 1-4

--

Counts

This parameter displays the CKP Learn offset in counts between cylinders.

Desired Idle Speed

--

800 RPM

This parameter displays the desired engine idle speed as commanded by the control module.

DTC Set This Ignition

--

No

This parameter displays Yes if a DTC set on the current ignition cycle.

ECT Sensor

--

0-5 Volts

This parameter displays the voltage of the engine coolant based on input to the control module from the engine coolant temperature (ECT) sensor.

ECT Sensor

--

-40° to +130°C (-40° to +266°°F)

This parameter displays the temperature of the engine coolant based on input to the control module from the engine coolant temperature (ECT) sensor.

EC Ignition Relay Command

Ignition ON

ON

This parameter displays the state of the control circuit for main relay as commanded by the control module.

EGR Position Sensor

--

0.6-0.75 Volts

This parameter displays the actual EGR pintle position in volts.

EGR Solenoid Command

--

0%

This parameter displays the state of the control circuit for EGR solenoid as commanded by the control module.

Engine Load

Engine Idling

20-30%

This parameter displays the calculated engine load in percent based on inputs to the control module from various engine sensors.

Engine speed at 2,500 RPM

10-20%

Engine Speed

Engine Cranking

Greater than 60 RPM

This parameter displays the speed of the engine crankshaft rotation from information received from the crankshaft position (CKP) sensor. If there is a CKP sensor DTC, the ECM calculates the engine speed from one of the camshaft position (CMP) sensors.

Engine Idling

Approximately 650-900 RPM

EVAP Purge Solenoid Command

--

0-100%

This parameter displays the on-time or duty cycle of the EVAP canister purge solenoid commanded by the control module. Zero percent indicates no purge. One hundred percent indicates full purge.

Fan High

Fan High Commanded ON

ON

This parameter displays the control module commanded state of the fan relay control circuit.

Fan Low

Fan Low Commanded ON

ON/OFF

This parameter displays the control module commanded state of the fan relay control circuit.

Fuel Gage Control

--

0-100%

This parameter displays control module commanded state of the fuel gage control circuit.

Fuel Level

--

0-100%

This parameter displays the amount of fuel in the fuel tank in percent of range, as calculated by the control module.

Fuel Level Sensor

--

0-5 Volts

This parameter displays the voltage signal received by the control module from the fuel level sensor.

Fuel Pump Relay Command

Ignition ON, engine OFF

Fuel pump on for 2 seconds

This parameter displays the control modules commanded state of the fuel pump relay control circuit.

Engine idling

On

HO2S 1 and 2 Heater Command

--

0-100%

This parameter displays the commanded state of the heater control circuit as commanded by the control module.

IAT Sensor

--

-39° to +140°C

(-38° to +284°F)

This parameter displays the temperature of the air entering the air induction system based on input to the control module from the intake air temperature (IAT) sensor.

IAT Sensor

--

0-5 Volts

This parameter displays the IAT sensor voltage.

Idle Switch

--

ON

This parameter displays if the engine is at idle. The parameter will change from ON to OFF when the engine is not at an idle.

Ignition 1 Signal

--

B+

This parameter displays B+ when the control module detects a voltage at the ignition 1 input terminal.

Injector PWM

--

0-9 ms

This parameter displays the average pulse width of the fuel injectors as determined by the control module.

ISC Command

--

0-100%

This parameter displays the ECM command for the idle speed control (ISC) motor position in percentage. The higher the number, the greater the commanded idle speed reads. The ISC responds to changes in the engine load in order to maintain the desired idle speed.

ISC Motor Position Sensor

--

0-100%

This parameter displays the ECM command for the idle speed control (ISC) motor position in percentage. The higher the number, the greater the commanded idle speed reads. The ISC responds to changes in the engine load in order to maintain the desired idle speed.

ISC Motor Position Sensor

--

0-5 Volts

This parameter displays the actual position for the ISC motor position in voltage.

Knock Sensor

--

0-5 Volts

This parameters displays the voltage input to the control module from the knock sensor (KS).

Long Term FT

--

0%

This parameter displays the commanded Long Term Fuel Trim correction by the control module.

Loop Status

--

Closed Loop

This parameter displays the state of the fuel control system as commanded by the control module. Closed Loop operation indicates that the control module is controlling the fuel delivery based off the oxygen sensors input signal. In Open Loop operation the control module ignores the oxygen sensor input signal and bases the amount of fuel to be delivered on other sensor inputs.

LT FT Cruise/Accel.

--

0%

This parameter displays the commanded Long Term Fuel Trim correction by the control module for cruise and acceleration conditions.

LT FT Idle/Decel.

--

0%

This parameter displays the commanded Long Term Fuel Trim correction by the control module for idle and deceleration conditions.

MAP Sensor

--

32-40 kPa

This parameter displays the pressure from the MAP sensor to the control module

MAP Sensor

--

0-5 Volts

This parameter displays the signal voltage from the MAP sensor to the control module.

MIL Command

--

Off

This parameter displays the commanded state of the malfunction indicator lamp (MIL) control circuit by the control module.

O2S/HO2S 1 or 2

--

Varies 400-800 mV

This parameter displays the voltage output from the H/O2S to the control module. A lower voltage indicates a lean exhaust, while a higher voltage indicates a rich exhaust.

Octane Level

--

Counts

This parameter displays counts.

Short Term FT Avg.

--

-3% to +3%

This parameter displays the short-term correction to the fuel delivery by the control module in response to oxygen sensor. If the oxygen sensor indicates a lean air/fuel mixture, the control module will add fuel increasing the short term fuel trim above 0. If the oxygen sensor indicates a rich air/fuel mixture, the control module will reduce fuel decreasing the short term fuel trim below 0.

Short Term FT

--

-3% to +3%

This parameter displays the short-term correction to the fuel delivery by the control module in response to oxygen sensor. If the oxygen sensor indicates a lean air/fuel mixture, the control module will add fuel increasing the short term fuel trim above 0. If the oxygen sensor indicates a rich air/fuel mixture, the control module will reduce fuel decreasing the short term fuel trim below 0.

Spark

--

2-10 Degrees

This parameter displays the amount of spark advance the control module is commanding on the ignition control circuits. The control module determines the desired advance.

TP Sensor

--

4.0-4.5 Volts

This parameter displays the actual voltage on the TP sensor signal circuit as measured by the control module.

TP Sensor

--

3-5%

This parameter displays the percent of throttle opening as calculated by the control module using information from the throttle position (TP) sensor.

Transmission Gear Position Signal

--

Park/Neutral

This parameter displays the position of the transmission gear selector that is transmitted over the serial data circuit from the transmission control module (TCM).

Vehicle Security Status

--

Disabled

This parameter displays the status of the vehicle theft deterrent system. The normal parameter display for the theft deterrent system is Disabled. If a condition exists with the theft deterrent system the parameter will display Enabled and the vehicle will not start.

Vehicle Speed Sensor

--

Km/h

mph

This parameter displays the speed of the vehicle as calculated by the transmission control module (TCM) from information received from the vehicle speed sensor (VSS).

Engine Control Module (ECM) Scan Tool Output Controls

Output Control

Description

A/C Relay

Important: This function is only allowed with the ignition ON, engine OFF.

This function controls the A/C compressor relay. When commanded ON, the A/C compressor will cycle ON/OFF for 3-5 seconds.

EGR Solenoid

Important: This function is only allowed with the ignition ON, engine OFF.

This function controls the exhaust gas recirculation (EGR) solenoid. When commanded ON, the EGR solenoid will cycle from 0-100 percent for 3-5 seconds. This output can also be monitored on the scan tool by observing the EGR Position Sensor data parameter.

Engine Controls Ignition Relay

Important: This function is only allowed with the ignition ON, engine OFF.

This function controls the engine control ignition relay or MAIN relay. When commanded ON, the engine control ignition relay will cycle ON/OFF for 3-5 seconds.

EVAP Purge Solenoid

Important: This function is only allowed with the ignition ON, engine OFF.

This function controls the evaporative emission (EVAP) purge solenoid. When commanded ON, the EVAP purge solenoid will cycle ON/OFF for 3-5 seconds. This output can also be monitored on the scan tool by observing the EVAP Purge Solenoid Command data parameter.

Fan High

Important: This function is only allowed with the ignition ON, engine OFF.

This function controls the high speed cooling fan relay. When commanded ON, the cooling fan will turn ON at high speed for 5 seconds.

Fan Low

Important: This function is only allowed with the ignition ON, engine OFF.

This function controls the low speed cooling fan relay. When commanded ON, the cooling fan will turn ON at low speed for 5 seconds.

Fuel Pump Relay

Important: This function is only allowed with the ignition ON, engine OFF.

This function controls the fuel pump relay. When commanded ON, the fuel pump relay will cycle ON/OFF for 3-5 seconds.

IAC Motor Position

Important: This function is only allowed with the ignition ON, engine OFF.

This function activates the idle air control (IAC) valve to change position. The system will cycle the IAC valve for 3-5 seconds. This output can also be monitored on the scan tool data parameter IAC Position.

Idle Learn Reset

This function resets the base idle value learned by the engine control module (ECM).

ISC Actuator

Important: This function is only allowed with the ignition ON, engine OFF.

This function controls the idle speed control (ISC) actuator. The ECM actuates the ISC actuator for 3-5 seconds when commanded ON. This output can also be monitored on the scan tool by observing the TP Sensor data parameter.

ISC System

This function resets the learned values for the idle speed control (ISC) system in the ECM.

Malfunction Indicator Lamp

This function controls the malfunction indicator lamp (MIL). When commanded ON with the engine running, the ECM turns the (MIL) ON/OFF for 3-5 seconds. When commanded OFF with the ignition ON, engine OFF, the ECM turns the MIL ON/OFF for 3-5 seconds.

Reset ECM

This function resets all the values learned by the ECM.

Engine Control Module Scan Tool Information 2.0L

Table 1: Engine Control Module Scan Tool Data
Table 2: Engine Control Module (ECM) Scan Tool Output Controls

The Engine Control Module Scan Tool Data List contains all engine-related parameters that are available on the scan tool. This is a master list arranged in alphabetical order and not all the parameters listed are in every engine platform.

Use the Engine Scan Tool Data List only after the following is determined:

    • The Diagnostic System Check - Vehicle is completed.
    • No diagnostic trouble codes (DTCs)
    • On-board diagnostics are functioning properly

The scan tool values from a properly running engine may be used for comparison with the engine you are diagnosing. The Engine Scan Tool Data List represents values that would be seen on a normally running engine.

Important: A scan tool that displays faulty data should not be used. The scan tool concern should be reported to the manufacturer. Use of a faulty scan tool can result in misdiagnosis and unnecessary parts replacement.

Only the parameters listed below are referenced in this service manual for use in diagnosis.

Engine Control Module Scan Tool Data

Parameter

System State

Expected Value

Description

Base Operating Conditions: Engine Idling/Radiator Hose Hot/Park or Neutral/Closed Loop

5 Volt Reference 1or 2

Ignition ON

5 Volts

This parameter displays the output voltage from the 5-volt reference circuit to the control module. This parameter only supports one 5-volt reference output from the control module.

A/C High Side Pressure

A/C OFF

0-5 Volts

This parameter displays the voltage from the A/C high side pressure sensor signal circuit to the control module.

A/C ON

0-5 Volts

A/C High Side Pressure

A/C OFF

450-650 kPa (65-95 psi)

This parameter displays the pressure from the A/C high side pressure sensor signal circuit to the control module.

A/C ON

650-800 kPa (95-105 psi)

A/C Relay Command

A/C ON

On

This parameter displays the state of the air conditioning (A/C) clutch relay control circuit as commanded by the control module.

A/C Request Signal

A/C ON

Yes

This parameter displays the state of the A/C request input to the control module from the heating, ventilation, and air conditioning (HVAC) controls.

Air Flow Calculated

--

3-6 g/s

This parameter displays the calculated air flow into the engine that is based on manifold absolute pressure. The calculation is used in several diagnostics to determine when to run the diagnostics.

Air Fuel Ratio

--

Ratio 14.7:1

This parameter displays the air to fuel ratio based on the oxygen sensor inputs. The engine control module (ECM) uses the fuel trims to adjust fueling in order to attempt to maintain an air fuel ratio of 14.7:1.

APP Indicated Angle

--

Varies

This parameter displays the angle of the accelerator pedal position (APP) as calculated by the control module using the signals from the APP sensors.

APP Sensor 1or 2

--

Varies

This parameter displays the actual percentage of each APP sensor signal circuit as measured by the control module.

BARO

--

65-104 kPa (8-16 psi) - Varies with altitude

This parameter displays the barometric pressure. The control module uses the barometric pressure sensor input for fuel control to compensate for altitude differences.

Case Diagnostic Learning

--

Learned

This parameter displays Learned if the control module has completed the CKP System Variation Learn Procedure.

Catalytic Converter Protection Active

--

No

This parameter displays if the control module is commanding catalytic converter protection.

Cmmd. A/F Equivalence Ratio

--

Ratio 1.0:1

This parameter displays the air to fuel ratio based on throttle state. The control module changes the ratio for acceleration or deceleration.

CMP Active Counter

--

1-3 Counts

This parameter displays the camshaft position (CMP) active counts. If the control module does not detect a signal from the CMP sensor, the counter will not increment.

Coolant Hot Lamp

--

Off

This parameter displays the control modules commanded state of the hot mode lamp.

Cruise Control Active

Cruise Control ON

Yes

This parameter displays the status of the cruise control system as determined by the control module.

Cruise Disengage 1-5 History

--

Varies

This parameter displays the history of the action taking with the cruise system.

Cruise Lamp Command

Cruise Control ON

Yes

This parameter displays the state of the cruise lamp to the instrument panel (IP) cluster as requested by the control module.

Cruise ON/OFF Switch

Cruise Control ON

Yes

This parameter displays the state of the ON/OFF switch input to the control module.

Cruise Resume/Accel. Switch

Cruise Resume/Accel. Switch ON

Active

This parameter displays the state of the Resume/Accel switch input to the control module from the cruise control system.

Cruise Set/Coast Switch

Cruise Set/Coast Switch ON

Active

This parameter displays the state of the Set/Coast switch input to the control module from the cruise control system.

Decel Fuel Cut Off

--

Inactive

This parameter displays the status of the operating mode of the control module used to turn off the fuel injectors during certain deceleration conditions.

Desired EGR Position

--

Varies

This parameter displays the desired exhaust gas recirculation (EGR) position as commanded by the control module.

Desired IAC Position

--

Counts

This parameter displays the desired idle air control (IAC) position as commanded by the control module.

Desired Idle Speed

--

750-950 RPM

This parameter displays the desired engine idle speed as commanded by the control module.

Distance Since DTC Cleared

--

Varies

This parameter displays the mileage that has elapsed since the DTC cleared.

ECT Sensor

--

-39 to +140°C ( -38 to +284°F)

This parameter displays the temperature of the engine coolant based on input to the control module from the engine coolant temperature (ECT) sensor.

EGR Flow Test Count

--

Counts

This parameter displays the number of EGR flow test samples collected during the current ignition cycle.

EGR Learned Minimum Position

--

Varies

This parameter displays the exhaust gas recirculation (EGR) valve minimum position in percent of range learned by the control module.

EGR Learned Minimum

--

Varies

This parameter displays the learned minimum value of the EGR valve as recorded by the control module during the last learn procedure.

EGR Position Sensor

--

Varies

This parameter displays the actual EGR pintle position in percentage.

EGR Position Sensor

--

Varies

This parameter displays the actual EGR pintle position in volts.

EGR Position Variance

--

Counts

This parameter displays the difference between the actual command of the EGR valve and the desired position of the EGR valve. This parameter displays the state of the EVAP vent solenoid as commanded by the control module.

EGR Solenoid Command

--

Varies

This parameter displays the state of the control circuit for EGR solenoid as commanded by the control module.

Engine Load

Engine Idling

25-40%

This parameter displays the calculated engine load in percent based on inputs to the control module from various engine sensors.

Engine speed at 2,500 RPM

25-40%

Engine Run Time

Engine Operating

0:00:00

Increments when the engine is operating

This parameter displays the time elapsed since the engine was started.

Engine Speed

Engine Cranking

Greater than 60 RPM

This parameter displays the speed of the engine crankshaft rotation from information received from the crankshaft position (CKP) sensor. If there is a CKP sensor DTC, the ECM calculates the engine speed from one of the camshaft position (CMP) sensors.

Engine Idling

Approximately 750-950 RPM

EVAP Purge Solenoid Command

--

0-100%

This parameter displays the on-time or duty cycle of the EVAP canister purge solenoid commanded by the control module. Zero percent indicates no purge. One hundred percent indicates full purge.

EVAP Vent Solenoid Command

--

Venting

This parameter displays the state of the EVAP vent solenoid as commanded by the control module.

Fail Counter

--

Counts

This parameter displays the number of times a DTC failed

Fan High Speed Command

Fan High Speed ON

On

This parameter displays the control module commanded state of the fan relay control circuit.

Fan Low Speed Command

Fan Low Speed ON

On

This parameter displays the control module commanded state of the fan relay control circuit.

Fuel Level Gage Command

--

Varies

This parameter displays the control module commanded state of the fuel gage control circuit.

Fuel Level to Cluster

--

Varies

This parameter displays the control module commanded state of the fuel gage control circuit.

Fuel Level Sensor

--

0-100%

This parameter displays the amount of fuel in the fuel tank in percent of range, as calculated by the control module.

Fuel Level Sensor

--

0-5 Volts

This parameter displays the voltage signal received by the control module from the fuel level sensor.

Fuel Pump Relay Command

Ignition ON, engine OFF

Fuel pump on for 2 seconds

This parameter displays the control modules commanded state of the fuel pump relay control circuit.

Engine idling

On

Fuel Tank Pressure Sensor

--

Varies

This parameter displays the pressure/vacuum inside the fuel tank. A negative value indicates a vacuum, while a positive value indicates a pressure.

Fuel Tank Pressure Sensor

--

0-5 Volts

This parameter displays the voltage signal received by the control module from the fuel tank pressure (FTP) sensor.

Fuel Trim Cell

--

Cell Number

This parameter displays what fuel trim cell that is currently active.

Fuel Trim Learned

--

Enabled

This parameter displays Enabled when conditions are appropriate for enabling long term fuel trim corrections. This indicates that the long term fuel trim is adapting continuing amounts of short term fuel trim. If the scan tool displays Disabled, then long term fuel trim will not respond to changes in short term fuel trim.

HO2S 1 or HO2S 2 Heater

--

Varies

This parameter displays the amperage of the HO2S heater commanded by the control module.

IAC Position

--

15-40 counts

 

IAT Sensor

--

-39° to +140°C

(-38° to +284°F)

This parameter displays the temperature of the air entering the air induction system based on input to the control module from the intake air temperature (IAT) sensor.

Ignition 1 Signal

--

B+

This parameter displays B+ when the control module detects a voltage at the ignition 1 input terminal.

IMT Valve Command

--

Off

This parameter displays the commanded state of the IMT valve solenoid by the control module.

IMT Valve Position Sensor

--

Varies

This parameter displays the percentage in range based on input to the control module the control module from the IMT valve position sensor.

Injector PWM Average

--

0-9 ms

This parameter displays the average pulse width of the fuel injectors as determined by the control module.

Knock Retard

--

Degrees

This parameter indicates the amount of spark advance the control module removes from the ignition control (IC) spark advance in response to the signal from the knock sensors.

KS Active Counter

--

Counts

This parameters displays the number of times the control module detects activity from the knock sensor.

Long Term FT

--

0-2%

This parameter displays the commanded Long Term Fuel Trim correction by the control module.

Long Term FT Average

--

0%

This parameter displays the commanded Long Term Fuel Trim correction by the control module.

Loop Status

--

Closed Loop

This parameter displays the state of the fuel control system as commanded by the control module. Closed Loop operation indicates that the control module is controlling the fuel delivery based off the oxygen sensors input signal. In Open Loop operation the control module ignores the oxygen sensor input signal and bases the amount of fuel to be delivered on other sensor inputs.

Low Fuel Lamp Command

Low Fuel Lamp Command ON

On

This parameter displays the control modules commanded state of the low fuel lamp.

MAP Sensor

--

32-50 kPa

This parameter displays the pressure from the MAP sensor to the control module

MAP Sensor

--

0-5 Volts

This parameter displays the signal voltage from the MAP sensor to the control module.

MIL Command

MIL Command ON

On

This parameter displays the commanded state of the malfunction indicator lamp (MIL) control circuit by the control module.

Mileage Since First Failure

--

Varies

This parameter displays the mileage that has elapsed since the first emission failure.

Mileage Since Last Failure

--

Varies

This parameter displays the mileage that has elapsed since the last emission failure.

Misfire Current Cyl. 1-4

--

0-255 Counts

This parameter displays the number of misfires that have been detected during the last 200 cylinder firing events. The counters may normally display some activity, but the activity should be nearly equal for all of the cylinders, and in low numbers.

Misfire Detects Rough Road

Rough Road Detected

Yes

This parameter displays the detection of a rough road during misfire detection by the control module.

Misfire History Cyl. 1-4

--

0-255 Counts

The misfire history counters display the total level of misfire that has been detected on each cylinder. The misfire history counters will not update or show any activity until a misfire DTC P0300 has become active. The misfire history counters will update every 200 cylinder firing events.

Not Run Counter

--

Counts

This parameter displays the number of times a DTC does not run.

O2S/HO2S 1 or 2

--

Varies 400-800 mV

This parameter displays the voltage output from the H/O2S to the control module. A lower voltage indicates a lean exhaust, while a higher voltage indicates a rich exhaust.

O2S/HO2S 1 Ready

--

Yes

This parameter displays that the HO2S 1 is at operating temperature.

Pass Counter

--

Counts

This parameter displays the number of times a DTC passed.

PNP Switch

--

Park/Neutral

This parameter displays whether the transmission range selector is in park/neutral or in gear.

Power Enrichment

--

Inactive

This parameter displays the status of the operating mode of the control module used to increase fuel delivery during certain acceleration conditions.

Power Steering Pressure Switch

--

Normal Pressure

This parameter displays the state of the power steering pressure switch.

Rich/Lean to Lean/Rich Ratio Sensor 1

--

Counts

This parameter displays the oxygen sensor rich/lean to lean/rich ratio. The rich/lean average is divided by the lean/rich average in order to determine the oxygen sensor ratio.

Rich/Lean to Transition Sensor 1

--

Counts

This parameter displays the oxygen sensor rich/lean and lean/rich switches. A switch is when the oxygen sensor voltage goes above 450 mV and below 450 mV.

Reduced Engine Power

--

No

This parameter displays the status of the operating mode of the control module used to reduce engine power to prevent catalytic converter or engine damage or due to a Throttle Actuator Control (TAC) system failure.

Rough Road Sensor

--

0-5 Volts

This parameter displays the voltage from the rough road sensor.

Rough Road Signal-ABS

--

0-5 Volts

This parameter displays the voltage from the ABS module for the rough road signal.

Short Term FT Avg.

--

-3% to +3%

This parameter displays the short-term correction to the fuel delivery by the control module in response to oxygen sensor. If the oxygen sensor indicates a lean air/fuel mixture, the control module will add fuel increasing the short term fuel trim above 0. If the oxygen sensor indicates a rich air/fuel mixture, the control module will reduce fuel decreasing the short term fuel trim below 0.

Short Term FT

--

-3% to +3%

This parameter displays the short-term correction to the fuel delivery by the control module in response to oxygen sensor. If the oxygen sensor indicates a lean air/fuel mixture, the control module will add fuel increasing the short term fuel trim above 0. If the oxygen sensor indicates a rich air/fuel mixture, the control module will reduce fuel decreasing the short term fuel trim below 0.

Spark

--

-20 to +40 Degrees

This parameter displays the amount of spark advance the control module is commanding on the ignition control circuits. The control module determines the desired advance.

Start Up ECT

--

-39° to +140°C

(-38° to +284°F)

This parameter displays the temperature of the engine coolant on start up based on input to the control module from the ECT sensor.

Start Up IAT

--

-39° to +140°C

(-38° to +284°F)

This parameter displays the temperature of the intake air at start in the air induction system based on input to the control module from the IAT sensor.

SVS Lamp Command

SVS Lamp Command ON

On

This parameter displays the control modules commanded state of the service vehicle soon lamp.

TAC Motor Command

TAC Motor Command ON

Varies

This parameter displays the percentage of the commanded state of the TAC motor by the control module.

TCC Enable Solenoid Command

TCC Enable Solenoid Command ON

On

This parameter displays the control module commanded state of the TCC solenoid.

Throttle Plate at Idle

--

Yes

This parameter displays whether the throttle plate at idle or not as calculated by the control module using information from the throttle position (TP) sensor. The scan tool will display Yes for the throttle plate to be at idle. The scan tool will display No when the throttle plate is opened.

Total Misfire

--

Counts

This parameter displays the total number of cylinder firing events that the control module detected as misfires for the last 200 crankshaft revolution sample period.

TP Angle

--

Varies

This parameter displays the percent of throttle opening as calculated by the control module using information from the two TP sensors.

TP Desired Angle

--

Varies

This parameter displays the desired TP angle commanded by the control module.

TP Indicated Angle

--

Varies

This parameter displays the actual TP angle indicated by the control module using information from the two TP sensors.

TP Sensor

--

0.0-0.3 Volts

This parameter displays the actual voltage on the TP sensor signal circuit as measured by the control module.

TP Sensor

--

5-15%

This parameter displays the percent of throttle opening as calculated by the control module using information from the throttle position (TP) sensor.

TP Sensor 1 or 2

--

Varies

This parameter displays the percent of throttle opening as calculated by the control module using information from the throttle position (TP) sensor.

Transmission Gear Position Signal

--

Park/Neutral

This parameter displays the position of the transmission gear selector that is transmitted over the serial data circuit from the transmission control module (TCM).

TWC Temperature Calculated

--

Varies

This parameter displays the catalytic converter temperature as calculated by the control module.

Vehicle Security Status

--

Disabled

This parameter displays the status of the vehicle theft deterrent system. The normal parameter display for the theft deterrent system is Disabled. If a condition exists with the theft deterrent system the parameter will display Enabled and the vehicle will not start.

Vehicle Speed Sensor

--

0 Km/h

0 mph

This parameter displays the speed of the vehicle as calculated by the transmission control module (TCM) from information received from the vehicle speed sensor (VSS).

Warm-ups Since DTC Cleared

--

Counts

This parameter displays the number of warm-ups since the DTC was cleared.

Wheel/Vehicle Speed Input

--

0 Km/h

0 mph

This parameter displays the speed of the vehicle as calculated by the control module from information received from the vehicle speed sensor (VSS) or wheel speed sensor depending on application.

Engine Control Module (ECM) Scan Tool Output Controls

Output Control

Description

A/C Relay

Important: The A/C Relay Command parameter may not change states when using this output control.

This function activates the A/C compressor relay. The normal commanded state of the A/C relay is None. The A/C compressor will turn ON/OFF when commanded ON/OFF. The system remains in the commanded state until cancelled by the scan tool. This output can also be monitored on the scan tool data parameter A/C Relay Command. The engine control module (ECM) will inhibit the operation of the A/C relay when the ambient air temperature is low.

Crankshaft Position Variation Learn

This function enables the engine control module (ECM) to learn the variations in the crankshaft position (CKP) system. The ECM will learn the variations once the following conditions are met:

    • Engine coolant temperature (ECT) is more than a predetermined value.
    • All the instructions on the scan tool have been completed.
    • Hold the accelerator pedal at wide open throttle (WOT) for 5 fuel cut-offs, as specified on the scan tool, then release accelerator pedal.

The ECM learns the variation values on the deceleration from fuel cut-off.

EGR Solenoid

Important: The EGR Position Sensor parameter may not properly change states when using this output control.

This function activates the exhaust gas recirculation (EGR) solenoid that controls EGR valve position. The normal commanded state is None. The system will increase or decrease the amount of EGR opening by 10 percent increments within a range of 0-100 percent. The EGR Position sensor parameter may not change states until commanded to 40 percent. This output can also be monitored on the scan tool data parameter EGR Position Sensor. The system remains in the commanded state until cancelled by the scan tool. If the engine is running, too much EGR will result in a rough idle and/or stalling.

EVAP Purge Solenoid

Important: 

   • This function may be disabled if there is an EVAP DTC set.
   • The EVAP Purge Solenoid Command parameter may not properly change states when using this output control.

This function controls the EVAP purge solenoid valve. The normal commanded state is None. The system will increase or decrease the amount of purge by changing the duty cycle of the purge valve in 10 percent increments within a range of 0-100 percent. The system remains in the commanded state until cancelled by the scan.

EVAP Vent Solenoid

Important: This function may be disabled if there is an EVAP DTC set.

This function controls the EVAP vent solenoid. The normal commanded state is None. When commanded ON, the vent valve switches to Not-venting. When commanded OFF, the vent valve switches to Venting. The system remains in the commanded state unless one of the following conditions occurs:

    • Cancelled by the scan tool
    • The fuel tank pressure (FTP) sensor exceeds a predetermined value.

EVAP Purge/Seal

Simultaneously activates the purge solenoid in 10 percent increments from 0 to 100 percent and the vent solenoid. The device control will be aborted and inhibited if the FTP sensor exceeds 19 mm Hg (10 in H2O).

Fan High Speed

This function operates one engine cooling fan at high speed by enabling the fan high speed relay. The normal commanded state of the relay is None. When commanded ON/OFF, the cooling fan turns ON/OFF. The system remains in the commanded state until cancelled by the scan tool. The ECM allows relay control when the following conditions are met:

    • The ignition is ON, with the engine OFF.
    • The engine is running.
    • The transmission must be in Park or Neutral.
    • The A/C request is OFF.
    • The engine coolant temperature is less than a predetermined value.

Fan Low Speed

This function operates one engine cooling fan at high speed by enabling the fan high speed relay. The normal commanded state of the relay is None. When commanded ON/OFF, the cooling fan turns ON/OFF. The system remains in the commanded state until cancelled by the scan tool. The ECM allows relay control when the following conditions are met:

    • The ignition is ON, with the engine OFF.
    • The engine is running.
    • The transmission must be in Park or Neutral.
    • The A/C request is OFF.
    • The engine coolant temperature is less than a predetermined value.

Fuel Injector Test

Important: DTCs may set when using this output control.

This function operates the selected fuel injector ON/OFF. The normal commanded state is None. The ECM enables or disables the fuel injector ON/OFF when the test is initiated. The fuel injector remains in the commanded state until cancelled by the scan tool. The scan tool initiates the test when the following conditions are met:

    • The engine is running.
    • The vehicle speed is 0 km/h (0 mph).

Fuel Pump Relay

Important: DTCs may set when using this output control.

This function controls the fuel pump relay. The normal commanded state is None. The scan tool initiates the test when the following conditions are met:

    • There are no vehicle speed sensor DTCs set.
    • The vehicle speed is 0 km/h (0 mph).

When commanded ON/OFF, the ECM turns the fuel pump relay ON/OFF. If the engine is running and the fuel pump relay is commanded OFF, the engine will stall. This output can also be monitored on the scan tool data parameter Fuel Pump Relay Command. The system remains in the commanded state until cancelled by the scan tool or the ECM detects a vehicle speed.

Engine Speed

This function controls the idle speed override in 25 RPM, 100 RPM, and 500 RPM increments, from the base idle speed to 1,400 RPM. The scan tool initiates the test when the following conditions are met:

    • The transmission is in park or neutral.
    • The engine speed is less than 1,000 RPM.

The engine speed will remain in the commanded state until cancelled by the scan tool.

IAC Motor Position

This function activates the idle air control (IAC) valve to change engine speed. The normal commanded state is None. The system will increase or decrease the amount of IAC opening by 5 percent increments within a range of 500-4,000 RPM. This output can also be monitored on the scan tool data parameter IAC Position. The system remains in the commanded state until cancelled by the tool.

IAC Reset

This function resets the IAC valve position and the learned values for the IAC system in the ECM.

IMT Valve

This function controls the intake manifold tuning (IMT) valve solenoid. The normal commanded state is None. When commanded ON/OFF, the ECM turns the IMT valve solenoid ON/OFF. The scan tool initiates the test when the following conditions are met:

    • There are no vehicle speed sensor DTCs set.
    • The vehicle speed is 0 km/h (0 mph).

The system remains in the commanded state until cancelled by the scan tool.

Malfunction Indicator Lamp

Important: The MIL Command parameter may not change states when using this output control.

This function controls the malfunction indicator lamp (MIL). The normal commanded state is None. When commanded ON/OFF, the ECM turns the malfunction indicator lamp (MIL) ON/OFF. This output can also be monitored on the scan tool data parameter MIL Command. The system remains in the commanded state until cancelled by the scan tool.

Throttle Position

This function controls the throttle valve in 10 percent increments. The scan tool initiates the test when the following conditions are met:

    • There are no vehicle speed sensor DTCs set.
    • The vehicle speed is 0 km/h (0 mph).
    • The ignition is ON, with the engine OFF.
    • The ECM is not commanding a throttle learn.

The system remains in the commanded state until cancelled by the scan tool.