|
|
DESCRIPTION AND OPERATION POWERTRAIN CONTROL MODULE (PCM) DESCRIPTION The Powertrain Control Module (PCM) (Fig. 1) is located in the engine compartment. The PCM is OPERATION The PCM operates the fuel system. The PCM is a pre-programmed, triple microprocessor digital com- The PCM receives input signals from various switches and sensors. Based on these inputs, the The PCM adjusts ignition timing based upon inputs it receives from sensors that react to: engine tion (automatic transmission), vehicle speed and the The PCM adjusts idle speed based on inputs it receives from sensors that react to: throttle position, Based on inputs that it receives, the PCM adjusts ignition coil dwell. The PCM also adjusts the gener- NOTE: PCM Inputs: • A/C request (if equipped with factory A/C) • A/C select (if equipped with factory A/C) • Auto shutdown (ASD) sense • Battery temperature • Battery voltage • Brake switch • CCD bus (+) circuits • CCD bus (-) circuits • Camshaft position sensor signal • Crankshaft position sensor • Data link connection for DRB scan tool • Engine coolant temperature sensor • Fuel level • Generator (battery voltage) output • Ignition circuit sense (ignition switch in on/off/ crank/run position) • Intake manifold air temperature sensor • Leak detection pump (switch) sense (if equipped) • Manifold absolute pressure (MAP) sensor • Oil pressure • Output shaft speed sensor • Overdrive/override switch • Oxygen sensors • Park/neutral switch (auto. trans. only) • Power ground • Sensor return • Signal ground • Speed control multiplexed single wire input • Throttle position sensor • Transmission governor pressure sensor • Transmission temperature sensor • Vehicle speed inputs from ABS or RWAL system NOTE: PCM Outputs: • A/C clutch relay • Auto shutdown (ASD) relay • CCD bus (+/-) circuits for: speedometer, voltme- ter, fuel gauge, oil pressure gauge/lamp, engine temp. • Data link connection for DRB scan tool • EGR valve control solenoid (if equipped) • EVAP canister purge solenoid Fig. 1 PCM Location 1 – RIGHT FRONT FENDER 14 - 28 FUEL SYSTEM DN |