RAM 1500 Truck 4WD V8-5.9L VIN Z (2002)
Engine Control Module: Description and Operation
Description
Fig. 3 Powertrain Control Module (PCM) Location
POWERTRAIN CONTROL MODULE
The Powertrain Control Module (PCM) is located in the right-rear section of the engine compartment under the cowl. The PCM is referred to as JTEC
.
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 (automatic transmission), vehicle speed, power steering pump pressure, 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.
PCM Inputs:
-
ABS module (if equipped)
-
A/C request (if equipped with factory A/C)
-
A/C select (if equipped with factory A/C)
-
A/C pressure transducer
-
Auto shutdown (ASD) sense
-
Battery temperature sensor
-
Battery voltage
-
Brake switch
-
J1850 bus (+) circuits
-
J1850 bus (-) circuits
-
Camshaft position sensor signal
