DeVille V8-4.6L VIN Y (1998)
Powertrain Control Module: Description and Operation
PCM Outputs
DESCRIPTION
Their are two types of PCM outputs, device outputs and output signals. Device outputs are components that the PCM controls their function as either ON
/ OFF or with a Pulse Width Modulated signal that can vary the components operation. Output signals are used by the PCM to communicate certain
operating conditions with other modules in the vehicle. Output signals can also be ON I OFF or PWM type signals.
OPERATION
The PCM typically controls both the device outputs and the output signals by completing the ground path of the circuit. Most outputs are monitored for
failures and will set a DTC. A scan tool can also command most of the outputs ON in order to diagnose failures.
PCM device outputs include the following:
^
The Fuel Pump relay.
^
The Fuel Injectors.
^
The EGR Valve.
^
The EVAP Purge Solenoid.
^
The EVAP Vent Valve.
^
The Idle Air Control valve.
^
The A/C Compressor Clutch relay.
^
The Cooling Fan relays.
^
The MIL lamp.
^
The transmission solenoids.
PCM output signals include the following:
^
Vehicle Speed output
^
Cruise Inhibit output
^
Fuel Enable output
^
Delivered Torque output
^
Engine Speed (Tach) output
