GM Service Manual Online
For 1990-2009 cars only

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 OFF. 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. The engine control module (ECM) will inhibit the operation of the A/C relay when the ambient air temperature is low.

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 OFF. 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.

Fuel Pump Relay

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 OFF. The scan tool initiates the test with the ignition ON and the engine OFF. When commanded ON/OFF, the ECM turns the fuel pump relay ON/OFF. 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.

Ignition Coil Cyl. 1-4 and 2-3

Special Functions/Engine Output Controls

This function controls the ignition coils. The normal commanded state is None. The ignition coils will turn ON/OFF when commanded ON/OFF. The ignition coil remains in the commanded state until cancelled by the scan tool.

Engine Speed Control

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.

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.