DESCRIPTION
The Powertrain Control Module (PCM) (Fig. 1) is located in the engine compartment. The PCM is referred to as JTEC.
Fig. 1 PCM Location
1 - RIGHT FRONT FENDER
2 - PCM MOUNTING BOLTS (3)
3 - 32-WAY CONNECTORS (3)
4 - COVER
5 - POWERTRAIN CONTROL MODULE (PCM)
OPERATION
The PCM operates the fuel system. The PCM is a pre-programmed, triple microprocessor digital computer.
It regulates ignition timing, air-fuel ratio, emission control devices, charging system, certain transmission features, speed control, air conditioning compressor clutch engagement and idle speed. The PCM can adapt its programming to meet changing operating conditions.
The PCM receives input signals from various switches and sensors. Based on these inputs, the PCM regulates various engine and vehicle operations through different system components. These components are referred to as Powertrain Control Module (PCM) Outputs. The sensors and switches that provide inputs to the PCM are considered Powertrain Control Module (PCM) Inputs.
The PCM adjusts ignition timing based upon inputs it receives from sensors that react to: engine rpm, manifold absolute pressure, engine coolant temperature, throttle position, transmission gear selection selection (automatic transmission), vehicle speed and the brake switch.
The PCM adjusts idle speed based on inputs it receives from sensors that react to: throttle position, vehicle speed, transmission gear selection, engine coolant temperature and from inputs it receives from the air conditioning clutch switch and brake switch.
Based on inputs that it receives, the PCM adjusts ignition coil dwell. The PCM also adjusts the generator charge rate through control of the generator field and provides speed control operation.
NOTE: PCM Inputs:
NOTE: PCM Outputs:
gauge and speed control warn. lamp
Driven through CCD circuits.