GM Service Manual Online
For 1990-2009 cars only

Scan Tool Output Control

Additional Menu Selection(s)

Description

A/C Compressor

Engine Output Controls

Activates the A/C compressor relay. The normal commanded state of the A/C relay is NONE. The relay status can also be monitored on the scan tool data parameter A/C Relay Command. The PCM allows A/C compressor relay control when the following conditions are met:

    • The ignition is ON or the engine is running
    • The blower motor select switch is ON
    • The powertrain control module (PCM) will inhibit the operation of the A/C relay when the ambient air temperature low enough to cause icing of the evaporator core.

Cam Valve Timing

Engine Output Controls

Activates the camshaft position (CMP) actuator solenoid valve. The normal commanded state of the CMP actuator solenoid is NONE. When commanded ON, the CMP actuator solenoid is operated at 100 percent duty cycle and the engine will stall. The PCM allows CMP actuator solenoid control when the following conditions are met:

    • DTC P0010, P0011, or P0012 are not set.
    • The engine is running
    • No vehicle speed is detected

Operation of the CMP actuator solenoid can be monitored on the parameter Camshaft Phase Solenoid Command. The solenoid remains in the commanded state until any of the following conditions occur:

    • Cancelled by the scan tool
    • The engine stalls
    • Vehicle speed is detected

Check Mode

--

Check Mode engine operation enhances the PCM's ability to detect certain engine control system malfunctions. When entering the output control, the default commanded state is NONE or NORMAL. In order to enter check mode operation refer to Service Bay Test .

Check mode operation can be monitored on the data parameter Diagnostic Mode. The PCM remains in the commanded state until cancelled by the scan tool or until the ignition switch is cycled.

EVAP Press. Switching Sol.

Engine Output Controls / EVAP System

Activates the evaporative emission (EVAP) pressure switching solenoid. The normal commanded state is NONE. When commanded ON, the pressure switching solenoid allows vapor pressure to equalize throughout the EVAP system.

The solenoid remains in the commanded state until cancelled by the scan tool or until vehicle speed is detected.

EVAP Purge Solenoid

Engine Output Controls / EVAP System

Activates the EVAP canister purge valve. The normal commanded state is NONE. When commanded ON, the purge solenoid operates near 50 percent duty cycle. The solenoid remains in the commanded state until cancelled by the scan tool or until vehicle speed is detected.

EVAP Vent Solenoid

Engine Output Controls / EVAP System

Activates the EVAP vent solenoid. The normal commanded state is NONE. When commanded ON, the vent valve switches to non-venting. The solenoid remains in the commanded state until cancelled by the tool or until vehicle speed is detected.

EVAP Purge/Seal

Engine Output Controls / EVAP System

Activates the EVAP purge, vent, and pressure switching solenoids. The normal commanded state is NONE. When commanded ON, the EVAP purge, vent, and pressure switching solenoids are all turned ON at the same time. After a preset vacuum pressure is achieved, the purge solenoid is turned OFF, leaving the vent and pressure switching solenoids still commanded ON. The vent and pressure switching solenoids remain in the commanded ON state for approximately 120 seconds. The system stays in the commanded state, unless cancelled by the scan tool or until vehicle speed is detected.

Fuel Injector Modification

Fuel System

Enables fuel injector to INCREASE or DECREASE fuel delivery by changing fuel injector pulse width (PW). The PCM increases or decreases the PW in 1 percent increments as commanded. The commanded range is from -12 to +25 percent.

The solenoid remains in the commanded state until cancelled by the scan tool or until engine speed exceeds 3,000 RPM.

Fuel Pump

Engine Output Controls

Controls the fuel pump relay. The normal commanded state is NONE. When commanded ON, the PCM turns the fuel pump relay ON. If the engine is running, fuel pump command is disabled. The relay remains in the commanded state until cancelled by the scan tool or until engine speed is detected.

Misfire Graphic

--

Displays the accumulated misfires occurring in each cylinder in a bar graph. The scan tool allows for a reset of the misfire graph.

RPM Control

IAC System

Activates the idle air control (IAC) valve in order to change engine RPM. The normal commanded state is 27-34 percent duty cycle. IAC valve operation can be monitored on the scan tool data parameter IAC Motor Command. In order to enable RPM control, the vehicle must be in Park or Neutral, and all instructions on the scan tool must be completed. The system will INCREASE or DECREASE the RPM within the IAC Motor Command range of 35-90 percent. The engine speed will increase or decrease accordingly from 750-3,000 RPM at approximately 80°C (176°F).

The system remains in the commanded state until cancelled by the scan tool or when vehicle speed is detected.