and front seat passenger to electrically adjust their
seating positions for optimum control and comfort
using the power seat switches located on the out-
board seat cushion side shield of each front seat. The
driver side power front seat can be adjusted in eight
different directions: up, down, front up, front down,
rear up, rear down, forward, rearward and recliner
forward and rearward. The passenger side power
front seat can be adjusted in four different directions:
forward, rearward and recliner forward and rear-
ward.

The power seat system receives battery current

through a 40 amp fuse in the Intelligent Power Mod-
ule and a 30 amp circuit breaker under the seat so
that the power seats remain operational, regardless
of the ignition switch position.

WARNING: SOME VEHICLES ARE EQUIPPED WITH
SEATBACK MOUNTED AIRBAGS (Fig. 1). BEFORE
ATTEMPTING TO DIAGNOSE OR SERVICE ANY
SEAT OR POWER SEAT SYSTEM COMPONENT
YOU MUST FIRST DISCONNECT AND ISOLATE THE
BATTERY NEGATIVE CABLE. THEN WAIT TWO MIN-
UTES FOR THE SYSTEM CAPACITOR TO DIS-
CHARGE BEFORE FURTHER SYSTEM SERVICE.
THIS IS THE ONLY SURE WAY TO DISABLE THE
AIRBAG SYSTEM. FAILURE TO DO SO COULD
RESULT IN ACCIDENTAL AIRBAG DEPLOYMENT
AND POSSIBLE PERSONAL INJURY.

A eight-way driver side power seat is standard on

highline models and optional on others. This option
includes a six-way adjustable seat cushion track and
a two-way power seat back.

The eight-way driver side power seat is also avail-

able with the heated seat and/or memory seat system
that automatically positions the power seat for two
different drivers. Refer to Heated Seats for more
information on the heated seat option. Refer to
Description - Memory System in this section for
more information on the memory seat system.

8N - 50

POWER SEAT SYSTEM

The power seat system includes the following com-

ponents:

• Power seat recliners

• Power seat switches

• Power seat tracks

• Circuit breaker
The power seat system with memory and heated

seat options includes the following components:

• Power seat recliner

• Power seat switch

• Power seat track.

• Memory Seat Mirror Module (MSMM)

• Memory set switch

• Heated Seat Module (HSM)

• Heated seat switch

• Electronic Vehicle Information Center (EVIC)

• Programmable Communications Interface (PCI)

data bus network

Refer to Wiring Diagrams for complete circuit dia-

grams. Following are general descriptions and opera-
tions for the major components in the power seat
system and memory seat system.

DESCRIPTION - MEMORY SYSTEM

An electronic memory system is available on some

models. The memory system is able to store and
recall the driver side power seat positions (including
the power recliner position) and both outside side
view mirrors positions for two drivers. On vehicles
equipped with a factory radio, the memory system is
also able to store and recall radio station presets for

two drivers. The memory system also will store and
recall the last station listened to for each driver, even
if it is not one of the preset stations.

The memory system will automatically return to

its preset settings when the corresponding numbered
button of the memory switch is depressed, or when
the doors are unlocked using the corresponding
Remote Keyless Entry (RKE) transmitter. A customer
programmable feature of the memory system allows
the RKE recall of memory features to be disabled, if
desired. This programmable feature is internal in the
EVIC module, which is located in the overhead con-
sole.

A Memory Seat Mirror Module (MSMM) is used on

some models to control and integrate the many elec-
tronic functions and features included in the memory
seat and mirror systems.

The memory system includes the following compo-

nents:

• Memory Seat Mirror Module (MSMM)

• Memory set switch

• Position potentiometers on both outside side

view mirrors

• Position potentiometers on the driver side power

seat track and power seat recliner motors.

• Electronic Vehicle Information Center (EVIC)

• Radio receiver (if PCI data bus capable).
Certain functions of the memory system rely upon

resources shared with other electronic modules in the
vehicle

over

the

Programmable

Communications

Interface (PCI) J1850 data bus network. The PCI
data bus network allows the sharing of sensor infor-
mation. This helps to reduce wire harness complexity,
internal controller hardware, and component sensor
current loads. At the same time, this system provides
increased

reliability,

enhanced

diagnostics,

and

allows the addition of many new feature capabilities.
Initial diagnosis of these electronic modules or the
PCI data bus network requires the use of a DRBIII

scan tool and the proper Diagnostic Procedures man-
ual. If this method does not prove conclusive, the use
of a automotive meter such as the Fluke

t, the proper

wiring schematics and the service manual diagnostic
routines are required.

The other electronic modules that may affect mem-

ory system operation are as follows:

• Body Control Module (BCM) - Refer to Body

Control Module in Electronic Control Modules for
more information.

• Powertrain Control Module (PCM) - Refer to

Powertrain Control Module in Electronic Control
Modules for more information.

• Transmission Control Module (TCM) - Refer

to Transmission Control Module in Electronic
Control Modules for more information.

Fig. 1 Identifying a Side Airbag Equipped Seat

1 - Airbag Label

POWER SEAT SYSTEM

8N - 51

POWER SEAT SYSTEM (Continued)

Refer to Heated Seat System for more informa-

tion on the heated seat system. Refer to Remote
Keyless Entry System in Power Lock Systems for
more information on the RKE system.

Refer to Wiring Diagrams for complete circuit

diagrams. Following are descriptions, theory of oper-
ation, diagnosis/testing procedures and removal/in-
stallation procedures of the major components in the
memory and power seat systems.

OPERATION

OPERATION - POWER SEAT SYSTEM

The power seat system receives battery current

through fuse #22 in the Intelligent Power Module
and a circuit breaker under the front seats, regard-
less of the ignition switch position.

When a power seat switch control knob or knobs

are actuated, a battery feed and a ground path are
applied through the switch contacts to the appropri-
ate power seat track adjuster motor. The selected
adjuster motor operates to move the seat track
through its drive unit in the selected direction until
the switch is released, or until the travel limit of the
seat track is reached. When the switch is moved in
the opposite direction, the battery feed and ground
path to the motor are reversed through the switch
contacts. This causes the adjuster motor to run in the
opposite direction.

No power seat switch should be held applied in any

direction after the seat track has reached its travel
limit. The power seat track each contain a self-reset-
ting circuit breaker to protect them from overload.
However, consecutive or frequent resetting of the cir-
cuit breaker must not be allowed to continue, or the
motor may be damaged. Refer to the owner’s manual
in the vehicle glove box for more information on the
features, use and operation of the power seat system.

OPERATION - MEMORY SYSTEM

The Memory Seat Mirror Module (MSMM) receives

battery current through fuse #22 in the Intelligent
Power Module and the power seat system circuit
breaker, located under the driver side front seat near
the rear edge of the seat cushion pan. The memory
system does not operate with the Ignition-Off Draw
(IOD) fuse removed. The MSMM will drive a maxi-
mum of 2 motors at a time in a given direction. If
conflicting directions are requested, the priority for
response will be approximately as follows:

• Seat Track Rearward or Forward

• Seat Front Down or Up

• Seat Rear Down or Up

• Recliner Rearward or Forward

The inputs from these switches to the MSMM is a

current limited battery source fed by the MSMM.
This protects the MSMM printed circuit board traces
from acting as fuses. All of these switch contact
inputs to the MSMM are normally closed to ground,
except when actuated.

See the owner’s manual in the vehicle glove box for

more information on the features, use and operation
of the memory system. For diagnosis of the MSMM,
the PCI data bus, or the other electronic modules on
the PCI data bus that provide inputs and outputs for
the memory system, the use of a DRBIII

t scan tool

and the proper Diagnostic Procedures manual are
recommended.

ELECTRONIC VEHICLE INFORMATION CENTER

The Electronic Vehicle Information Center (EVIC)

serves as the user interface for the memory system.
It displays memory system status messages and pro-
vides the user with the means for enabling and dis-
abling the many customer programmable features
available on the vehicle, including those for the mem-
ory system.

See the owner’s manual in the vehicle glove box for

more information on the features, use and operation
of the EVIC. Refer to Electronic Vehicle Informa-
tion Center in Overhead Console Systems for more
information on the EVIC.

DIAGNOSIS AND TESTING

DIAGNOSIS AND TESTING - POWER SEAT
SYSTEM

Following are tests that will help to diagnose the

hard wired components and circuits of the power seat
system. However, if the vehicle is also equipped with
the optional memory system, these tests may not
prove conclusive in the diagnosis of the driver side
power seat. In order to obtain conclusive testing of
the driver side power seat with the memory system
option, the Programmable Communications Interface
(PCI) data bus network and all of the electronic mod-
ules that provide inputs to, or receive outputs from
the memory system components must be checked.

The most reliable, efficient, and accurate means to

diagnose the driver side power seat with the memory
system option requires the use of a DRBIII

t scan tool

and the proper Diagnostic Procedures manual. The
DRBIII

t scan tool can provide confirmation that the

PCI data bus is functional, that all of the electronic
modules are sending and receiving the proper mes-
sages on the PCI data bus, and that the memory sys-
tem is receiving the proper hard wired inputs and
relaying the proper hard wired outputs to perform its
driver side power seat functions.

8N - 52

POWER SEAT SYSTEM

POWER SEAT SYSTEM (Continued)

WARNING: SOME VEHICLES ARE EQUIPPED WITH
SEATBACK

MOUNTED

AIRBAGS.

BEFORE

ATTEMPTING TO DIAGNOSE OR SERVICE ANY
SEAT OR POWER SEAT SYSTEM COMPONENT
YOU MUST FIRST DISCONNECT AND ISOLATE THE
BATTERY NEGATIVE CABLE. THEN WAIT TWO MIN-
UTES FOR THE SYSTEM CAPACITOR TO DIS-
CHARGE BEFORE FURTHER SYSTEM SERVICE.
THIS IS THE ONLY SURE WAY TO DISABLE THE
AIRBAG SYSTEM. FAILURE TO DO SO COULD
RESULT IN ACCIDENTAL AIRBAG DEPLOYMENT
AND POSSIBLE PERSONAL INJURY.

(1) If the vehicle is equipped with the memory sys-

tem and the driver side power seat exhibits a inter-
rupted or jerky motion, there is a possibility that the
wires leading from the memory seat module to the
memory seat motor are mis-wired. To check the con-
cern, obtain a DRBIII

t scan tool and energize each

axis one at a time. If any axis stops in approximately
2 seconds (without hitting the end of travel), the
feedback for that axis may have an open, short or be
mis-wired. Check the wiring to that axis (module to
motor). Fix any wiring problems and retry that axis.

(2) If any power seat is not operational in any

direction, check the power seat circuit breaker,
located under the trailing edge of the driver side
power seat. Refer to the Power Distribution section of
this service manual for the circuit breaker diagnosis
and testing procedure.

(3) If the power seat circuit breaker is OK, check

for proper battery and ground connections at the
power seat switch and/or memory seat module. Fix
any wiring problems and retry.

(4) Check the power seat system wire harness con-

nections and pins to ensure proper circuit continuity
and ground paths. For complete circuit diagrams,
refer to Wiring Diagrams.

(5) With the dome lamp on, apply the power seat

switch in the direction of the failure. If the dome
lamp dims, the seat may be jamming. Check under
and behind the seat for binding or obstructions. If
the dome lamp does not dim, proceed with testing of
the individual components and circuits in the power
seat system.

DIAGNOSIS AND TESTING - MEMORY SYSTEM

In order to obtain conclusive testing of the memory

system, the Programmable Communications Interface
(PCI) data bus network and all of the electronic mod-
ules that provide inputs to, or receive outputs from
the memory system components must be checked.

The most reliable, efficient, and accurate means to

diagnose the memory system requires the use of a
DRB III

t scan tool and the proper Diagnostic Proce-

dures manual. The DRB III

t scan tool can provide

confirmation that the PCI data bus is functional, that
all of the electronic modules are sending and receiv-
ing the proper messages on the PCI data bus, and
that the memory system is receiving the proper hard
wired inputs and relaying the proper hard wired out-
puts to perform its functions.

(1) If the driver power seat exhibits a interrupted

or jerky motion, there is a possibility that the wires
leading from the memory seat module to the memory
seat motor are mis-wired. To check the concern,
obtain a DRB III

t scan tool and energize each axis

one at a time. If any axis stops in approximately 2
seconds (without hitting the end of travel), the feed-
back for that axis may have an open, short or be mis-
wired. Check the wiring to that axis (module to
motor). Fix any wiring problems and retry that axis.
Refer to Wiring Diagrams for complete circuit sche-
matic or connector pin-out information.

DRIVER SEAT SWITCH

DESCRIPTION

Vehicles equipped with a driver side power seat

utilize an eight-way power seat switch. This eight-
way power seat switch features two knobs ganged
together on the outboard seat cushion side shield
(Fig. 2).

The switch is secured to the back of the seat cush-

ion side shield with two screws. However, the control

Fig. 2 Power Seat Switch Location

1 - Power Seat Switch
2 - Seat Cushion Side Shield

POWER SEAT SYSTEM

8N - 53

POWER SEAT SYSTEM (Continued)

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