ELECTRICALLY HEATED SYSTEMS
CONTENTS
page
HEATED SEATS ........................... 1
HEATED SEATS
INDEX
page page
GENERAL INFORMATION
INTRODUCTION ......................... 1
DESCRIPTION AND OPERATION
HEATED SEAT CONTROL MODULE ........... 2
HEATED SEAT ELEMENTS AND SENSOR ...... 2
HEATED SEAT SWITCH .................... 2
DIAGNOSIS AND TESTING
HEATED SEAT CONTROL MODULE ........... 2
HEATED SEAT ELEMENT .................. 3
HEATED SEAT SWITCH .................... 2
HEATED SEAT SYSTEM ................... 2
REMOVAL AND INSTALLATION
HEATED SEAT CONTROL MODULE ........... 4
HEATED SEAT SWITCH .................... 3
GENERAL INFORMATION
INTRODUCTION
Individually controlled electrically heated front
seats are available factory-installed optional equip-
ment on this model. The seat heaters will only oper-
ate when the ignition switch is in the On position,
and the surface temperature at the front seat heating
element sensors is below the temperature set point
(1–6) on the heated seat switch.
There is a rotating six-position switch located in
the floor console that controls the temperature for
each front seat. Six positions can be selected, the 0
position set point is off and the (1–6) positions pro-
vide various temperature control for each front seat,
with position 6 being the warmest. When the switch
is turned on Light-Emitting Diodes (LED) will illumi-
nate the number on the switch to give a visual indi-
cation that the system is on. Each switch controls a
Heated Seat Control Module (HSCM) mounted to the
seat cushion frame under each front seat.
When a seat heater is turned on, a sensor located
near the seat cushion electric heater element pro-
vides the HSCM with an input indicating the surface
temperature of the seat cushion. If the surface tem-
perature input is below the temperature set point for
the selected switch position, a relay in the HSCM
energizes the heating elements in the seat cushion
and back. When the sensor input indicates the cor-
rect temperature set point has been achieved, the
HSCM de-energizes the relay. The HSCM will con-
tinue to cycle the relay as needed to maintain the
temperature set point.
The control circuit operates on ignition switched
power from a 10 amp fuse in cavity # 11 of the junc-
tion block and a 20 amp fused battery feed in cavity
# 11 of the Power Distribution Center. The system is
turned off automatically when the ignition switch is
turned to the Off – Lock position, and returns auto-
matically to the previously set heat setting when the
ignition switch is turned back ON. The heating ele-
ments operate on power supplied through a 20 amp
MAXI fuse located in the power distribution center in
the engine compartment. The HSCM automatically
disconnects power from the heating elements if it
detects an open in the sensor circuit, but the LED’s
will remain on. If the heating element shorts, caus-
ing excessive current draw, the 20 amp MAXI fuse in
the Power Distribution Center will blow and/or the
HSCM will disconnect power from the heating ele-
ments, but the LED’s will remain on.
Following are general descriptions of the major
components in the heated seat system. Refer to
8W-63 - Power Seat With Heated Seats in Group 8W
- Wiring Diagrams for complete circuit descriptions
and diagrams.
JA ELECTRICALLY HEATED SYSTEMS 8N - 1
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