GM Service Manual Online
For 1990-2009 cars only

Scan Tool Output Controls w/o Throttle Actuator Control

Scan Tool Output Control

Additional Menu Selection(s)

Description

A/C Relay

Special Functions/Engine Output Controls

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

Special Functions/Crankshaft Position Variation Learn

This function enables the 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

Special Functions/Engine Output Controls/EGR System

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. On some applications, the EGR Position sensor parameter may not change states until commanded to 40 percent and the upper limit will be less than 100 percent when commanded to 100 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

Special Functions/Engine Output Controls/EVAP System

Important: 

   • This function may be disabled if there is an evaporative emission (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 (If equipped)

Special Functions/Engine Output Controls/EVAP System

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.

Fans Low Speed

Special functions/Engine Output Control/Fan Relays

This function operates both engine cooling fans at low speed by enabling the fan low speed relay. The normal commanded state of the relay is None. When commanded ON/OFF, both cooling fans turn 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.

Fans High Speed

Special functions/Engine Output Control/Fan Relays

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

Special Functions/Fuel System

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

Special Functions/Fuel System

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.

IAC Motor Position

Special Functions/Engine Output Controls/IAC System

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

Special Functions/Engine Output Controls/IAC System

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

IMT Valve (If equipped)

Special Functions/Engine Output Controls

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:

    • The engine is running at idle.
    • 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

Special Functions/Engine Output Controls

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 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.

Scan Tool Output Controls w/ Throttle Actuator Control

Scan Tool Output Control

Additional Menu Selection(s)

Description

A/C Relay

Special Functions/Engine Output Controls

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

Special Functions/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

Special Functions/Engine Output Controls/EGR System

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

Special Functions/Engine Output Controls/EVAP System

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 (If equipped)

Special Functions/Engine Output Controls/EVAP System

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

Engine Output Controls/EVAP System

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).

Fans Low Speed

Special functions/Engine Output Control/Fan Relays

This function operates both engine cooling fans at low speed by enabling the fan low speed relay. The normal commanded state of the relay is None. When commanded ON/OFF, both cooling fans turn 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.

Fans High Speed

Special functions/Engine Output Control/Fan Relays

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

Special Functions/Fuel System

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

Special Functions/Fuel System

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

Special Functions/Engine Output Controls

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.

IMT Valve (If equipped)

Special Functions/Engine Output Controls

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:

    • The engine is running at idle.
    • 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

Special Functions/Engine Output Controls

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

Special Functions/Engine Output Controls

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.