LEMON Manuals: Even more car manuals for everyone
Home >> Chevrolet >> 2004 >> Optra Base, Standard >> Repair and Diagnosis (Single Page) >> Engine Performance >> System >> Engine Controls - 1.8L (L79) - Diagnostic Information And Procedures >> Scan Tool Output Controls (w/o Throttle Actuator Control )

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.