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8N - 26
POWER SEAT SYSTEM
POWER SEAT SYSTEM (Continued)
the 12v battery feed and ground path to the selected
seat track motor to move the adjuster through its
drive unit until the switch is released, or until the
travel limit of the adjuster is reached. The Memory
Heated Seat Adjustable Pedal Module (MHSAPM) is
the main control module for the power, memory and
heated seat systems. The module will drive a maxi-
mum of 2 motors at a time in a given 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 motors each contain a
self-resetting circuit breaker to protect them from
overload. However, consecutive or frequent resetting
of the circuit breaker must not be allowed to con-
tinue, 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
When a memory switch button is actuated, a hard-
wired resistance signal is sent to the driver door
module. The driver door module then sends the
request to the Memory Heated Seat Adjustable Pedal
Module (MHSAPM) for the driver seat and pedals.
The driver door module would also send the request
to the radio for the preset stations. The passenger
door module would send the request to the MHSAPM
for the passenger outside mirror via the PCI data
bus circuit. The driver door module would send the
request to the MHSAPM for the driver outside mir-
ror. The MHSAPM is responsible for controlling the
12v battery feed and ground path to the selected
adjuster motor to move the seat track or pedal
assembly through its drive unit until the preset loca-
tion is reached.
The Memory Heated Seat Adjustable Pedal Module
is the main control module for the power, memory
seat and heated seat systems. The module will drive
a maximum of 2 motors at a time in a given direc-
tion. The software in the module allows it to know
where the seat and foot pedal assembly are located in
its designed travel by a resistance reading generated
from the seat track motor or pedal mounted potenti-
ometers.
The module will prevent the seat memory recall
function from being initiated, if the transmission
gear selector lever is not in the Park or Neutral posi-
tions, or if the vehicle is moving. These inputs are
monitored over the PCI data bus circuit by the
MHSAPM.
ELECTRONIC VEHICLE INFORMATION CENTER
The Electronic Vehicle Information Center (EVIC)
module serves as the user interface for the memory
system. It displays memory system messages in the
cluster display and provides the vehicle operator with
a means for enabling and disabling the customer pro-
grammable features available in the system.
Refer to Electronic Vehicle Information Center
in Overhead Console for more information on the
EVIC module. See the owner's manual in the vehicle
glove box for more information on the features, use
and operation of the memory system.
DIAGNOSIS AND TESTING
DIAGNOSIS AND TESTING - POWER SEAT
SYSTEM
The most reliable, efficient, and accurate means to
diagnose the power seat system requires the use of a
DRB III scan tool and the proper Diagnostic Proce-
dures manual. The DRB III
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 net-
work, and that the memory system is receiving the
proper hard wired inputs and relaying the proper
hard wired outputs to perform its power seat system
functions. The scan tool is used to retrieve any diag-
nostic trouble codes (DTC's) that could be related to
the power seat system.
Following are tests that will help to diagnose the
hard wired components and circuits of the power seat
system.
PRELIMINARY TESTS
(1) If any power seat is not operational in any
direction, check the power seat circuit breaker,
located in the Integrated Power Module. If OK, go to
Step 2. Refer to the Power Distribution section for
circuit breaker diagnosis and testing procedure.
(2) Check for proper battery or electrical system
voltage. The CS is equipped with a low-voltage cut-
off feature. If the electrical system voltage drops
below a predetermined set-point (approx. 11.5v), the
power seat system will not function until the proper
system voltage has been restored. If OK, go to Step
3. Refer to the Battery System and/or Charging Sys-
tem section for testing instructions.
(3) Obtain a DRB III scan tool and check for any
stored diagnostic trouble codes recorded in the mem-
ory (heated) seat adjustable pedal module. Follow the
procedures called out in the proper diagnostic proce-
dures manual to resolve if codes are present.
(4) Using a DRB III scan tool, energize each seat
track motor axis one at a time. If any axis stops
without hitting the end of travel, the potentiometer
signal 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.
CS
scan tool can provide
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