Powertrain Control Module (Pcm)

The Powertrain Control Module (PCM), located on right side firewall, is a preprogrammed, dual microprocessor digital computer that receives various input signals from sensors and switches, and provides the necessary signals to output devices to achieve optimum engine performance conditions.

The PCM has a voltage converter that converts battery voltage to a regulated 5-volt output. The regulated 5-volt output is used to power Camshaft Position (CKP) sensor, Crankshaft Position (CKP) sensor, Manifold Absolute Pressure (MAP) sensor, Throttle Position (TP) sensor, Vehicle Speed Sensor (VSS) and logic circuits.

The ignition and fuel injection systems are controlled by the PCM, based on present engine operating conditions. PCM is programmed to provide a precise amount of fuel and the correct ignition timing to meet existing engine speed and load requirements.

The PCM adjusts ignition timing based on inputs it receives from CKP sensor, CMP sensor, MAP sensor, Engine Coolant Temperature (ECT) sensor, TP sensor, VSS, transmission gear selection (A/T only) and brake switch (also known as stop lamp switch).

The PCM adjusts idle speed based on inputs it receives from TP sensor, VSS, transmission gear selection (A/T only), A/C clutch switch and brake switch. The PCM also controls the speed (cruise) control system and generator charge rate by controlling the generator field.

NOTE: Components are grouped into 2 categories. The first category covers INPUT DEVICES, which control or produce voltage signals that are monitored by the PCM. The second category covers OUTPUT SIGNALS, which are components controlled by the PCM.