Chrysler 2004 Pacifica, Руководство по обслуживанию, Страница: 2019 / 3603

Pedal Module (MHSAPM). The module detects the
heated seat switch status via the PCI data bus cir-
cuit and energizes the appropriate heated seat ele-
ment. The programmed software in the MHSAPM
allows it to know the temperature of the seat cushion
by a resistance value generated from the heated seat
temperature sensor. When the correct preset temper-
ature set point is achieved the module will de-ener-
gize the heated seat element. The module will
continue to toggle the heated seat element 12v sup-
ply ON and OFF to maintain the selected tempera-
ture of the seat.
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 drivers front door trim panel
mounted, adjustable foot pedal switch sends a hard-
wired, resistor multi-plexed signal to the drivers door
module. The door module then sends a PCI data bus
message to the Memory Heated Seat/Adjustable
Pedal Module (MHSAPM). The module detects the
adjustable pedal switch status via the PCI data bus
circuit and energizes the appropriate foot pedal
motor. 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 vehicle 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
8G - 14 HEATED SEAT SYSTEM
CS
HEATED SEAT MODULE - FRONT SEATS (Continued)