MEMORY SEAT SYSTEM OPERATION
Depressing any of the drivers front door trim panel
mounted, memory seat switches sends a hardwired,
resistor multi-plexed signal to the drivers door mod-
ule. The door module then sends a PCI data bus mes-
sage to the Memory Heated Seat/Adjustable Pedal
Module (MHSAPM). The module detects the memory
seat switch status via the PCI data bus circuit and
energizes the appropriate power seat motors. The
programmed software in the MHSAPM allows it to
know the location of the seat track by a resistance
value generated from the seat track mounted poten-
tiometers.
When
the
correct
preset
location
is
achieved the module will de-energize the power seat
track motors. The MHSAPM will prevent the seat
memory recall function from being initiated if the
transmission gear selector lever is not in the Park or
Neutral positions, or if the vehicle is moving. These
inputs are monitored over the PCI data bus circuit.
ADJUSTABLE FOOT PEDAL SYSTEM OPERATION
Depressing the adjustable foot pedal switch sends
a hardwired, resistor multi-plexed signal to the driv-
ers door module. The door module then sends a PCI
data bus message to the Memory Heated Seat/Ad-
justable Pedal Module (MHSAPM). The module
detects the adjustable pedal switch status via the
PCI data bus circuit and energizes the appropriate
foot pedal motor. When the foot pedal switch is
released the module will stop the motor.
Depressing the memory switch will signal the mod-
ule to move the pedal assembly to the prepro-
grammed position. The programmed software in the
MHSAPM allows it to know the location of the foot
pedal assembly by a resistance value generated from
the pedal assembly mounted potentiometer. When
the correct preset location is achieved the module
will de-energize the foot pedal motor. The MHSAPM
will prevent the adjustable foot pedal function from
being initiated if the transmission gear selector lever
is not in the Park or Neutral positions, or if the vehi-
cle is moving. These inputs are monitored over the
PCI data bus circuit also.
DIAGNOSIS AND TESTING - HEATED SEAT
MODULE - FRONT SEATS
In order to obtain conclusive testing of the memory
heated seat adjustable pedal module, the Program-
mable Communications Interface (PCI) data bus cir-
cuit and any components that provide inputs to the
module must be checked.
The most reliable, efficient, and accurate means to
diagnose the module requires the use of a DRB III
t
scan tool and the Service and Body Diagnostic Proce-
dures Manuals. The DRB III
t scan tool can provide
vital information to the technician trying to find a
problem with the module. Diagnostic logic software is
built into the memory heated seat adjustable pedal
module to help the person trying to locate the prob-
lem by the most efficient means possible. Anytime a
problem is suspected, a DRB III
t scan tool should be
obtained and used to retrieve any stored fault codes
in the memory heated seat adjustable pedal module.
If diagnostic fault codes are present in the module,
record them on a piece of paper immediately before
proceeding any further. Then, use these fault codes to
identify the problem by verifying the fault code.
Example, If the module records “DRIVER SEAT
HEAT OUTPUT OPEN” fault, locate the diagnostic
procedure for this code in the appropriate Body Diag-
nostic Procedures Manual and follow the flow chart
until the specific problem is located and resolved.
Once the problem is corrected, erase the stored fault
code using the DRB III
t scan tool and verify correct
heated seat system operation. If the heated seat sys-
tem appears to be functioning correctly, verify that
there are no other stored codes in the module and
return the vehicle to service.
If the fault code could not be verified, such as not
finding anything wrong when following the diagnos-
tic flow chart in the Body Diagnostic Procedures
Manual. This is a good indication that a INTERMIT-
TENT problem may be present. You must than
attempt to find the intermittent problem, such as
moving the heating element within the seat while
testing continuity or wiggling the wire harness’s/elec-
trical connectors under the seat while testing conti-
nuity. Always, eliminate all other potential problems
before attempting to replace the memory heated seat
adjustable pedal module.
For complete circuit wiring diagrams, refer to Wir-
ing.
PRELIMINARY TEST
Before testing the individual components in the
suspect system, check the following:
(1) Using the DRB III
t scan tool, check the mem-
ory heated seat adjustable pedal module (MHSAPM)
for any stored fault codes. Record these codes on
paper for reference and resolve using the appropriate
Body Diagnostic Procedures Manual.
(2) Check the vehicles battery open-circuit voltage
and charging system performance. If the vehicles
electrical system is defective or weak it may not be
suppling sufficient voltage to operate the system in
question.
REMOVAL
(1) Position the drivers seat as far upward and
rearward as possible.
(2) Open hood, disconnect and isolate the negative
battery cable.
CS
HEATED SEAT SYSTEM
8G - 15
HEATED SEAT MODULE - FRONT SEATS (Continued)