components in the power distribution system. See the
owner’s manual in the vehicle glove box for more
information on the features and use of all of the
power distribution system components.

OPERATION

The power distribution system for this vehicle is

designed to provide safe, reliable, and centralized dis-
tribution points for the electrical current required to
operate all of the many standard and optional facto-
ry-installed

electrical

and

electronic

powertrain,

chassis, safety, security, comfort and convenience sys-
tems. At the same time, the power distribution sys-
tem was designed to provide ready access to these
electrical distribution points for the vehicle techni-
cian to use when conducting diagnosis and repair of
faulty circuits. The power distribution system can
also prove useful for the sourcing of additional elec-
trical circuits that may be required to provide the
electrical current needed to operate many accessories
that the vehicle owner may choose to have installed
in the aftermarket.

8W-97 POWER DISTRIBUTION SYSTEM

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SPECIAL TOOLS

POWER DISTRIBUTION SYSTEMS

ACCESSORY RELAY

DESCRIPTION

The accessory relay is an electromechanical device

that switches fused battery current to the accessory
powered vehicle circuits when the ignition switch is
turned to the Accessory or On positions. The delay
feature will maintain power to the accessories for 45
seconds after the ignition is shut off or until a door is
opened. This allows sufficient time to close windows
and park the windshield wipers. The accessory relay
is located in the Integrated Power Module (IPM) in
the engine compartment.

The accessory relay is a International Standards

Organization (ISO) relay. Relays conforming to the
ISO specifications have common physical dimensions,
current capacities, terminal patterns, and terminal
functions.

The accessory relay cannot be repaired or adjusted

and, if faulty or damaged, it must be replaced.

OPERATION

The ISO relay consists of an electromagnetic coil, a

resistor or diode, and three (two fixed and one mov-
able) electrical contacts. The movable (common feed)
relay contact is held against one of the fixed contacts
(normally closed) by spring pressure. When the elec-
tromagnetic coil is energized, it draws the movable
contact away from the normally closed fixed contact,
and holds it against the other (normally open) fixed
contact.

When the electromagnetic coil is de-energized,

spring pressure returns the movable contact to the
normally closed position. The resistor or diode is con-
nected in parallel with the electromagnetic coil in the

relay, and helps to dissipate voltage spikes that are
produced when the coil is de-energized.

DIAGNOSIS AND TESTING

DIAGNOSIS & TESTING - ACCESSORY RELAY

The accessory relay (Fig. 1) is located in the Inte-

grated Power Module (IPM), in the engine compart-
ment. For complete circuit diagrams, refer to Wiring
Diagrams .

(1) Remove the accessory relay from the IPM.

Refer to Accessory Relay in the Removal and
Installation section of this group for the procedure.

(2) A relay in the de-energized position should

have continuity between terminals 87A and 30, and
no continuity between terminals 87 and 30. If OK, go
to Step 3. If not OK, replace the faulty relay.

(3) Resistance between terminals 85 and 86 (elec-

tromagnet) should be 75 ± 5 ohms. If OK, go to Step
4. If not OK, replace the faulty relay.

(4) Connect a battery to terminals 85 and 86.

There should now be continuity between terminals
30 and 87, and no continuity between terminals 87A
and 30. If OK, perform the Relay Circuit Test that
follows. If not OK, replace the faulty relay.

DIAGNOSIS & TESTING - RELAY CIRCUIT TEST

(1) The relay common feed terminal cavity (30) of

the IPM is connected to battery voltage and should
be hot at all times. Check for battery voltage at the
fused B(+) circuit cavity in the IPM receptacle for the
accessory relay. If OK, go to Step 2. If not OK, repair
the fused B(+) circuit to the IPM fuse as required.

(2) The relay normally closed terminal (87A) is

connected to terminal 30 in the de-energized position,
but is not used for this application. Go to Step 3.

(3) The relay normally open terminal (87) is con-

nected to the common feed terminal (30) in the ener-
gized position. This terminal supplies battery voltage

Terminal Pick Kit 6680

Fig. 1 Accessory Relay

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POWER DISTRIBUTION SYSTEM (Continued)

to the fused B(+) fuse in the IPM that feeds the
accessories when the relay is energized by the igni-
tion switch. There should be continuity between the
IPM cavity for relay terminal 87 and the fused B(+)
fuse in the IPM at all times. If OK, go to Step 4. If
not OK, repair the open fused B(+) circuit to the IPM
fuse as required.

(4) The coil ground terminal (85) is connected to

the electromagnet in the relay. It receives battery
feed to energize the accessory relay when the ignition
switch is in the Accessory or On positions. Turn the
ignition switch to the On position. Check for battery
voltage at the fused ignition switch output (acc/run)
circuit cavity for relay terminal 85 in the IPM recep-
tacle for the accessory relay. If OK, go to Step 5. If
not OK, repair the open fused ignition switch output
(acc/run) circuit to the ignition switch as required.

(5) The coil battery terminal (86) is connected to

the electromagnet in the relay. The IPM cavity for
this terminal should have continuity to ground at all
times. If not OK, repair the open ground circuit to
ground as required.

REMOVAL

(1) Disconnect and isolate the battery negative

cable.

(2) Remove the Integrated Power Module (IPM)

cover from the IPM.

(3) Remove the accessory relay from the IPM.

Refer to the IPM cover for relay location.

INSTALLATION

(1) Position the accessory relay in the proper

receptacle in the Integrated Power Module (IPM).

(2) Push in firmly on the accessory relay until the

terminals are fully seated in the terminal cavities in
the IPM receptacle.

(3) Install the IPM cover.
(4) Reconnect the battery negative cable.

INTEGRATED POWER MODULE

DESCRIPTION

The Integrated Power Module (IPM) is a combina-

tion of the Power Distribution Center (PDC) and the
Front Control Module (FCM). The IPM is located in
the engine compartment, next to the battery on this
model (Fig. 2). The power distribution center mates
directly with the Front Control Module (FCM) to
form the IPM Fuse and Relay Center. The power dis-
tribution center (PDC) is a printed circuit board
based module that contains fuses and relays, while
the front control module contains the electronics con-
trolling the IPM and other functions. This IPM con-
nects directly to the battery positive via a four pin

connector. The ground connection is via two other
connectors. The IPM provides the primary means of
voltage distribution and protection for the entire
vehicle.

The molded plastic IPM housing includes a base

and cover. The IPM cover is easily opened or removed
for service access by squeezing the two marked cover
latches and has a fuse and relay layout map integral
to the inside surface of the cover. This IPM housing
base and cover are secured in place by an IPM
mounting bracket. This mounting bracket is designed
to allow the IPM to rotate counter-clockwise once the
locking tab is disengaged. The IPM mounting bracket
is secured in place by bolts threaded into the left
front wheel house.

Replaceable components of the IPM assembly are

broken down into the following components: the
Power Distribution Center (PDC) (without fuses or
relays), the IPM cover, the Front Control Module
(FCM), the IPM mounting bracket, IPM bracket
retaining clips and the IPM assembly which includes
the power distribution center, the cover and FCM.
Refer to the Front Control Module in the Elec-
tronic Control Module section of this service
manual for information on the FCM.

OPERATION

All of the current from the battery and the gener-

ator output enters the Integrated Power Module
(IPM) via a four- pin connector on the bottom of the

Fig. 2 BATTERY THERMAL GUARD

1 - BATTERY THERMAL GUARD
2 - INTEGRATED POWER MODULE
3 - FRONT CONTROL MODULE

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ACCESSORY RELAY (Continued)

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