2500 4x4 Pickup V8-360 5.9L VIN 5 Magnum (1994)
Powertrain Control Module: Description and Operation
Modes of Operation
Acceleration
This is a OPEN LOOP mode.
- The Powertrain Control Module (PCM) recognizes an abrupt increase in throttle position or MAP pressure, as a demand for increased engine
output to accelerate vehicle.
- The PCM increases injector pulse width, in response to increased fuel demand.
Cruise
This is a CLOSED LOOP mode.
With engine at operating temperature, the Powertrain Control Module (PCM) receives inputs from:
- Air Conditioning Control Position
- Battery voltage
- Camshaft position (CMP) sensor
- Engine coolant temperature (ECT) sensor
- Manifold absolute pressure (MAP) sensor
- Intake air temperature (IAT) sensor
- Crankshaft position (CKP) sensor
- Throttle position sensor (TPS)
- Heated oxygen sensor (HO2S)
Based on these inputs the PCM will:
- Apply voltage to the injectors. The PCM then controls injection sequence and pulse width by switching individual injector ground paths on
and off.
- Monitor oxygen sensors and fine tune air/fuel ratio by varying injector pulse width.
- Adjust engine idle speed through the IAC motor.
- Adjust ignition timing.
- Operate A/C Compressor Clutch relay (if selected).
Deceleration
This is an OPEN LOOP mode.
During deceleration the the Powertrain Control Module (PCM) receives inputs from:
- Air Conditioning Control Position
- Battery voltage
- Camshaft position (CMP) sensor
- Engine coolant temperature (ECT) sensor
- Manifold Absolute Pressure (MAP) sensor
- Intake air temperature (IAT) sensor
- Crankshaft position (CKP) sensor
- Throttle Position Sensor (TPS)
Based on these inputs the PCM will:
- Adjust engine idle speed through the IAC motor.
- Adjust ignition timing.
- Operate A/C Compressor Clutch relay (if selected).
- Ignore oxygen sensor input. The PCM will enter fuel cut-off strategy (under hard deceleration).
- Determine proper injector pulse width and continue injection (under normal deceleration).
Engine Start-Up
This is an OPEN LOOP mode.
When the starter motor is engaged, the Powertrain Control Module (PCM) receives input from:
- Battery voltage
- Crankshaft position (CKP) sensor
- Engine coolant temperature (ECT) sensor
- Intake air temperature (IAT) sensor
- Throttle position sensor (TPS)
- Camshaft position (CMP) sensor
- Starter relay