GM Service Manual Online
For 1990-2009 cars only

Scan Tool Output Controls Except Holden

Scan Tool Output Control

Additional Menu Selection(s)

Description

A/C Relay

Special Functions/Engine Output Controls

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

Special Functions/Engine Output Controls

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

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

Engine Controls Ignition Relay

Special Functions/Engine Output Controls

Important: This function is only allowed with the ignition ON, engine OFF, and there are no DTCs set.

This function controls the engine controls ignition relay or MAIN relay. The relay is always ON when the ignition is ON or the engine is running. When commanded OFF, the engine controls ignition relay will turn OFF for 3-5 seconds. Commanding the relay OFF will set some DTCs, which must be cleared before the relay can be commanded OFF again.

EVAP Purge Solenoid

Special Functions/Engine Output Controls/EVAP System

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

This function controls the evaporate emission (EVAP) purge solenoid. The EVAP purge solenoid will cycle ON between 5 percent and 95 percent several times, when commanded ON. This output can be monitored on the scan tool by observing the EVAP Purge Solenoid Command data parameter.

Fan High

Special functions/Engine Output Controls/Fan Controls

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

Special functions/Engine Output Controls/Fan Controls

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

Special Functions/Engine Output Controls

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.

Injector 1-6

Special Functions/Engine Output Controls

This function controls the selected fuel injector while the engine is running. When commanded ON, the selected fuel injector will be turned OFF for 5 seconds. This output can also be monitored by observing the appropriate fuel control heated oxygen sensor (HO2S). The HO2S voltage should indicate lean, low voltage, when the fuel injector is turned OFF.

IMT Valve

Special Functions/Engine Output Controls

Important: 

   • This function is only allowed with the ignition ON, engine OFF.
   • Adequate vacuum must be stored in the reservoir for the intake manifold tuning (IMT) valve actuator to move when commanded by the scan tool.

This function controls the IMT valve solenoid. The IMT valve solenoid will cycle ON/OFF for 3-5 seconds several times, when commanded ON. This output can also be monitored by observing the IMT valve actuator move as the solenoid allows vacuum to it.

Malfunction Indicator Lamp

Special Functions/Engine Output Controls

This function controls the malfunction indicator lamp (MIL). With the engine running, the engine control module (ECM) flashes the MIL ON/OFF for 5 seconds.

Reset ECM

Special Functions/Engine Output Controls/Reset Learned Values

This function resets the all values learned by the ECM.

TAC Motor Command

Special Functions/Engine Output Controls

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

This function controls the throttle actuator control (TAC) motor. The ECM actuates the TAC motor to move the throttle plate from closed to open, for 3-5 seconds several times, when commanded ON. This output can be monitored on the scan tool by observing the TP Sensors and TAC Motor Command data parameters.

TAC System

Special Functions/Engine Output Controls/Reset Learned Values

This function resets the learned values for the throttle actuator control (TAC) system in the ECM.

Scan Tool Output Controls Holden

The Engine Scan Tool Data List contains all engine related parameters that are available on the scan tool. The list is arranged in alphabetical order. A parameter may appear in any one of the data lists, and in some cases may appear more than once, or in more than one data list in order to group certain related parameters together.

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

    • The Diagnostic System Check - Engine Controls is completed.
    • There are no diagnostic trouble codes (DTCs).
    • The on-board diagnostics are functioning correctly.

Scan tool values from an engine that is operating correctly may be used for comparison with the engine you are diagnosing. The Engine Scan Tool Data List represents the values that would be seen on a normal operating engine.

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

Only the parameters listed below are referenced in this service information for use in diagnosis. If all values are within the typical range described below, refer to Symptoms - Engine Controls for diagnosis.

Scan Tool Parameter

System State

Expected Values

Description

Engine Idling/Radiator Hose Hot/Park or Neutral/Closed Loop/Accessories Off

A/C Pressure (Air Conditioning)

On

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 Pressure (Air Conditioning)

On

Off

kPa

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

A/C Relay (Air Conditioning)

On

Off

-

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

APP Sensor 1 (Accelerator Pedal Position)

-

0-5 Volts

This parameter displays the actual voltage of the accelerator pedal position (APP) sensor 1 signal circuit as measured by the control module.

APP Sensor 2 (Accelerator Pedal Position)

-

0-5 Volts

This parameter displays the actual voltage of the accelerator pedal position (APP) sensor 2 signal circuit as measured by the control module.

B1 Average Injection Time (Bank 1)

-

ms

This parameter displays the amount of fuel injector ON time or pulse width as commanded by the engine control module.

B1 Long Term Fuel Trim (Bank 1)

-

-50 to +50%

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

B1 Short Term Fuel Trim (Bank 1)

-

-50 to +50%

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

B1S1 O2 Sensor (Bank 1 Sensor 1)

-

0-1,006 mV

This parameter displays the voltage output from the HO2S to the control module. A lower voltage indicates a lean exhaust, while a higher voltage indicates a rich exhaust.

B1S1 O2 Sensor Heater (Bank 1 Sensor 1)

-

0-100%

This parameter displays the % of the O2 sensor heater.

B1S2 O2 Sensor (Bank 1 Sensor 2)

-

0-1,006 mV

This parameter displays the voltage output from the HO2S to the control module. A lower voltage indicates a lean exhaust, while a higher voltage indicates a rich exhaust

B1S2 O2 Sensor Heater (Bank 1 Sensor 2)

-

0-100%

This parameter displays the % of the O2 sensor heater.

B2 Average Injection Time (Bank 2)

-

ms

This parameter displays the amount of fuel injector ON time or pulse width as commanded by the engine control module.

B2 Long Term Fuel Trim (Bank 2)

-

-50 to +50%

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

B2 Short Term Fuel Trim (Bank 2)

-

-50 to +50%

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

B2 Short Term Fuel Trim (Bank 2)

-

-50 to +50%

This parameter displays percentage. This parameter indicates the average of the short term fuel trim cells. The short fuel trim cells are rated, or weighted for the amount of which they are used.

For example, the control module rates an idle cell higher then a wide open cell. If a fueling malfunction occurs in the idle cell and the wide open, the idle cell would effect more than the wide open cell. 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.

B2S1 O2 Sensor (Bank 2 Sensor 1)

-

0-1,006 mV

This parameter displays the voltage output from the HO2S to the control module. A lower voltage indicates a lean exhaust, while a higher voltage indicates a rich exhaust.

B2S1 O2 Sensor Heater (Bank 2 Sensor 1)

-

%

This parameter displays the % of the O2 sensor heater.

B2S2 O2 Sensor (Bank 2 Sensor 2)

-

mV

This parameter displays the voltage output from the HO2S to the control module. A lower voltage indicates a lean exhaust, while a higher voltage indicates a rich exhaust.

B2S2 O2 Sensor Heater (Bank 2 Sensor 2)

-

%

This parameter displays the % of the O2 sensor heater.

Barometric Pressure

-

65-104 kPa

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

Battery Voltage

On

Off

Battery Voltage

This parameter displays 0 to 30 Volts. The voltage measured between the module’s battery positive voltage circuit and ground circuit.

Coolant Temperature

-

-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.

Coolant Temperature

-

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.

Cooling Fan High Speed

On

Off

-

This parameter displays the control module commanded state of the high speed cooling fan relay.

Cooling Fan Low Speed

On

Off

-

This parameter displays the control module commanded state of the low speed cooling fan relay.

Cruise Control

Off

On

Resume

Accel

Set

Coast

-

This parameter displays the state of the on/off switch input to the control module . The scan tool will display On when the cruise ON/OFF switch is on. The scan tool will display OFF when the cruise ON/OFF switch is OFF.

Cruise Resume/Accel Switch: This parameter displays the state of the Resume/Accel switch input to the control module When the cruise control switch is in the on position and the Resume/Accel switch is activated, the scan tool displays On. When the Resume/Accel switch is released the scan tool displays Off.

Cruise Set/Coast Switch: This parameter displays the state of the Set/Coast switch input to the control module from the cruise control system. When the cruise control switch is in the on position and the Set/Coast switch is activated, the scan tool displays On. When the Set/Coast switch is released the scan tool displays Off.

Desired Engine Idle Speed

-

RPM

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

EGR Position Command (Exhaust- Gas Recirculation)

-

0-100%

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

EGR Position Feedback (Exhaust Gas Recirculation)

-

0-5 Volts

This parameter displays the actual EGR pintle position in volts.

Engine Runtime

-

h:m:s

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

Engine Speed

-

RPM

This parameter displays the speed of the engine crankshaft rotation from information received from the crankshaft position (CKP) sensor.

EVAP Purge Solenoid (Evaporative Emission)

-

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.

Fuel Level Sensor

-

0-5 Volts

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

Fuel Level Sensor

-

0-100%

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

Fuel Pump Relay

Active

Inactive

-

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

Intake Air Temperature

-

-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.

Intake Air Temperature

-

0-5 Volts

This parameter displays the voltage intake air temperature (IAT) sensor.

Knock Retard Cylinder 1

-

°CA

This parameter indicates how much ignition spark timing is being retarded due to all control systems monitored by the engine control module. The scan tool will display a high value during extreme conditions such as high temperatures and antilock braking. The scan tool will display a lower value during lighter driving conditions.

Knock Retard Cylinder 2

-

Knock Retard Cylinder 3

-

Knock Retard Cylinder 4

-

Knock Retard Cylinder 5

-

Knock Retard Cylinder 6

-

MAP Sensor (Manifold Absolute Pressure)

-

kPa

This parameter displays the pressure from the manifold absolute pressure (MAP) sensor to the control module.

MAP Sensor (Manifold Absolute Pressure)

-

0-5 Volts

This parameter displays the signal voltage from the manifold absolute pressure (MAP) sensor to the control module.

Mass Air Flow Sensor

-

mg/strk

This parameter displays the measured quantity of air flowing into the engine during all operating conditions.

Spark

-

°

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.

Throttle Position PWM Servo Signal

-

%

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

Throttle Position Sensor

-

°

This parameter displays the degrees of throttle opening as calculated by the control module using information from the TP sensor.

TP Sensor 1 (Throttle Position)

-

0-5 Volts

This parameter displays the actual voltage of the throttle position (TP) sensor 1 signal circuit as measured by the control module.

TP Sensor 2 (Throttle Position)

-

0-5 Volts

This parameter displays the actual voltage of the throttle position (TP) sensor 2 signal circuit as measured by the control module.

Vehicle Security Status

Learned

Learn Pending

No Immobilizer

Not Learned

-

This parameter displays the status of the vehicle theft deterrent system. The normal parameter display for the theft deterrent system is Learned.

Vehicle Speed

-

km/h

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

VIM Solenoid (Variable Intake Manifold)

Open

Closed

-

This parameter displays the engine control modules commanded state of the VIM solenoid.

VIM Solenoid (Variable Intake Manifold)

-

V

This parameter displays the voltage of the engine control modules commanded state of the VIM solenoid.