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DR
ENGINE CONTROL MODULE (Continued)
To avoid possible voltage spike damage to either
the Engine Control Module ECM, ignition key must
be off, and negative battery cables must be discon-
nected before unplugging ECM connectors.
(2) Disconnect both negative battery cables at both
batteries.
(3) Remove the 50–way and 60–way connector
bolts at the ECM. Note: Tthe connector bolt is a
female allen head. As bolt is being removed, very car-
fully remove connectors from the ECM.
(4) Remove five ECM mounting bolts and remove
ECM form the vehicle (Fig. 3).
Fig. 3 DIESEL ECM
1 - ENGINE CONTROL MODULE (ECM)
2 - ECM MOUNTING BOLT
3 - 50-WAY CONNECTOR
4 - SUPPORT PLATE
5 - 60-WAY CONNECTOR
INSTALLATION
Do not apply paint to ECM. Poor ground will
result.
(1) Position ECM to ECM support bracket and
install five mounting bolts. Tighten bolts to 24 N·m
(18 ft. lbs.).
(2) Check pin connectors in ECM and the 50–way
and 60–way connectors for corrosion or damage.
Repair as necessary.
(3) Clean pins in the 50–way and 60–way electri-
cal connectors with a quick-dry electrical contact
cleaner.
(4) Very carefully install the 50–way and 60–way
connectors to ECM. Tighten connector allen bolts.
(5) Install both negative battery cables.
ELECTRONIC CONTROL MODULES
(6) Turn key to ON position. Without starting
engine, slowly press throttle pedal to floor and
then slowly release. This step must be done
(one time) to ensure accelerator pedal position
sensor calibration has been learned by ECM. If
not done, possible DTC's may be set.
(7) Use DRB scan tool to erase any stored compan-
ion DTC's from ECM.
FRONT CONTROL MODULE
DESCRIPTION
The Front Control Module (FCM) is a micro con-
troller based module located in the left front corner
of the engine compartment. On this model the inte-
grated power module must be positioned aside in
order to access the front control module. The front
control module mates to the power distribution cen-
ter to form the Integrated Power Module (IPM). The
integrated power module connects directly to the bat-
tery and provides the primary means of circuit pro-
tection
and
power
electrical systems. The front control module controls
power to some of these vehicle systems electrical and
electromechanical loads based on inputs received
from hard wired switch inputs and data received on
the PCI bus circuit (J1850).
For information on the Integrated Power Mod-
ule Refer to the Power Distribution Section of
the service manual.
OPERATION
As messages are sent over the PCI bus circuit, the
front control module reads these messages and con-
trols power to some of the vehicles electrical systems
by completing the circuit to ground (low side driver)
or completing the circuit to 12 volt power (high side
driver). The following functions are Controlled by
the Front Control Module:
• Headlamp Power with Voltage Regulation
• Windshield Wiper "ON/OFF" Relay Actuation
• Windshield Wiper "HI/LO" Relay Actuation
• Windshield Washer Pump Motor
• Fog Lamp Relay Actuation
• Park Lamp Relay Actuation
• Horn Relay Actuation
The following inputs are Received/Monitored by
the Front Control Module:
• B+ Connection Detection
• Power Ground
• Ambient Temperature Sensing
• Ignition Switch Run
• Washer Fluid Level Switch
• Windshield Wiper Park Switch
• PCI Bus Circuit
distribution
for
all
8E - 5
vehicle
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