Dodge ZB 2005 Service Manual page 243

8E - 6 ELECTRONIC CONTROL MODULES
POWERTRAIN CONTROL MODULE (Continued)
The PCM adjusts ignition timing based on the fol-
lowing inputs.
• Coolant temperature
• Intake air temperature
• Engine speed (crankshaft position sensor)
• Manifold absolute pressure
• Throttle position
The PCM also adjusts engine idle speed through
the idle air control motor based on the following
inputs.
• Air conditioning sense
• Battery voltage
• Coolant temperature
• Engine speed (crankshaft position sensor)
• Engine run time
• Manifold absolute pressure
• Throttle position
• Vehicle distance (speed)
The Auto Shutdown (ASD) and fuel pump relays
are mounted externally, but turned on and off by the
PCM.
The crankshaft position sensor signal is sent to the
PCM. If the PCM does not receive the signal within
approximately one second of engine cranking, it deac-
tivates the ASD relay and fuel pump relay. When
these relays deactivate, power is shut off the fuel
injectors, ignition coils, heating element in the
upstream oxygen sensors, hydraulic fan solenoid and
the fuel pump.
The PCM contains a voltage converter that
changes battery voltage to a regulated 5 volts direct
current to power the camshaft position sensor, crank-
shaft position sensor and vehicle speed sensor. The
PCM also provides a 5 volt direct current supply for
the manifold absolute pressure sensor and throttle
position sensor.
OPERATION - 5 VOLT SUPPLY - PCM OUTPUT
The PCM supplies 5 volts to the following sensors:
• A/C Pressure Transducer
• Ambient Temperature sensor
• Battery Temperature
• Camshaft Position Sensor (NGC)
• Crankshaft Position Sensor (NGC)
• Engine Coolant Temperature sensor
• Inlet Air Temperature Sensor
• Manifold Absolute Pressure Sensor
• Oil Pressure Sensor
• Throttle Position Sensor
STANDARD PROCEDURE - OBTAINING
DIAGNOSTIC TROUBLE CODES
BULB CHECK
Key on: Bulb illuminated until vehicle starts, as
long as all once per trip (readiness) monitors com-
pleted. If monitors have not been completed, then:
Key on: bulb check for approximately 14 seconds,
lamp then flashes (once per second) for approxi-
mately 11 seconds, then MIL remains illuminated
until vehicle is started.
OBTAINING DTC'S USING DRB SCAN TOOL
(1) Connect the DRBIII scan tool to the data link
(diagnostic) connector. This connector is located in
the passenger compartment; at the lower edge of
instrument panel; near the steering column.
(2) Turn the ignition switch on and access the
"Read Fault" screen.
(3) Record all the DTC's and "freeze frame" infor-
mation shown on the DRB scan tool.
(4) To erase DTC's, use the "Erase Trouble Code"
data screen on the DRB scan tool. Do not erase any
DTC's until problems have been investigated
and repairs have been performed.
REMOVAL
If the PCM is replaced of usage, update the mile-
age and vehicle identification number (VIN) in the
new PCM. Use the DRBIII scan tool to change the
mileage and VIN in the PCM. If this step is not done
a Diagnostic Trouble Code (DTC) may be set. Refer to
the appropriate Powertrain Diagnostic Manual and
the DRBIII scan tool.
To avoid possible voltage spike damage to PCM,
ignition key must be off, and the negative battery
cable must be disconnected before unplugging the
PCM connectors. Note radio programs.
The Powertrain Control Module Location (Fig. 4).
Fig. 4 PCM LOCATION
ZB