HEATED SEAT MODULE
Before testing the heated seat module, test the
heated seat switch, the heated seat elements, and the
heated seat sensor. Refer to Heated Seat Switch,
Heated Seat Element and Heated Seat Sensor in
the Diagnosis and Testing section of this group. If
testing of the heated seat switch, elements, and sen-
sor reveals no problems, proceed as follows. For com-
plete
circuit
diagrams,
refer
to
Power
Seat
Premium I/III in the Contents of Group 8W - Wir-
ing Diagrams.
(1) Disconnect and isolate the battery negative
cable. Disconnect both power seat wire harness con-
nectors from the Heated Seat Module (HSM) or
Memory Heated Seat Module (MHSM). Check for
continuity between each of the two Z1 ground circuit
cavities of the C2 power seat wire harness connector
for the HSM or MHSM and a good ground. There
should be continuity. If OK, go to Step 2. If not OK,
repair the open ground circuit to ground as required.
(2) Check for continuity between the Z2 ground
circuit cavity of the C1 power seat wire harness con-
nector for the HSM or MHSM and a good ground.
There should be continuity. If OK, go to Step 3. If not
OK, repair the open ground circuit to ground as
required.
(3) Reconnect the battery negative cable. Check for
battery voltage at each of the two fused B(+) circuit
cavities of the C2 power seat wire harness connector
for the HSM or MHSM. If OK, use a DRB scan tool
and the proper Diagnostic Procedures manual to test
the HSM or MHSM. If not OK, repair the open fused
B(+) circuit to the power seat circuit breaker in the
junction block as required.
HEATED SEAT ELEMENT
Two types of heated seat elements are offered,
which require two different testing methods. All
Laredo models use resistor wire heating elements for
each seat that are connected in series with the
Heated Seat Module (HSM) or the Memory Heated
Seat Module (MHSM). All Limited models use carbon
fiber mesh heating elements for each seat that are
connected in parallel with the HSM or the MHSM.
For complete circuit diagrams, refer to Power Seats
Premium I/III in the Contents of Group 8W - Wir-
ing Diagrams.
RESISTOR WIRE ELEMENT
(1) Disconnect and isolate the battery negative
cable. Disconnect the 4-way heated seat cushion ele-
ment wire harness connector from the power seat
wire harness. The power seat wire harness connec-
tors for the seat cushion and seat back heating ele-
ments are secured to a bracket located under the
rear edge of the seat cushion frame.
(2) Check for continuity between the seat heater
B(+) driver circuit cavity of the 4-way heated seat
cushion element wire harness connector and the seat
cushion frame. There should be no continuity. If OK,
go to Step 3. If not OK, replace the faulty seat cush-
ion cover trim and element unit.
(3) Check for continuity between the seat heater
B(+) driver circuit and the heated seat driver circuit
cavities of the 4-way heated seat cushion element
wire harness connector. There should be continuity. If
OK, go to Step 4. If not OK, replace the faulty seat
cushion cover trim and element unit.
(4) Disconnect the C2 connector of the power seat
wire harness from the Heated Seat Module (HSM) or
Memory Heated Seat Module (MHSM) connector
receptacle. Check for continuity between the seat
heater B(+) driver circuit cavity of the 4-way power
seat wire harness connector for the heated seat cush-
ion element and the seat cushion frame. There
should be no continuity. If OK, go to Step 5. If not
OK, repair the shorted seat heater B(+) driver circuit
as required.
(5) Check for continuity between the seat heater
B(+) driver circuit cavities of the 4-way power seat
wire harness connector for the heated seat cushion
element and the C2 power seat wire harness connec-
tor for the HSM or MHSM. There should be continu-
ity. If OK, go to Step 6. If not OK, repair the open
seat heater B(+) driver circuit as required.
(6) Disconnect the 2-way heated seat back element
wire harness connector from the power seat wire har-
ness. The power seat wire harness connectors for the
seat cushion heating element and the seat back heat-
ing element are secured to a bracket located under
the rear edge of the seat cushion frame.
(7) Check for continuity between the heated seat
driver circuit cavity of the 2-way power seat wire
harness connector for the heated seat back element
and the seat cushion frame. There should be no con-
tinuity. If OK, go to Step 8. If not OK, repair the
shorted heated seat driver circuit as required.
(8) Check for continuity between the heated seat
driver circuit cavities of the 2-way power seat wire
harness connector for the heated seat back element
and the 4-way power seat wire harness connector for
the heated seat cushion element. There should be
continuity. If OK, go to Step 9. If not OK, repair the
open heated seat driver circuit as required.
(9) Check for continuity between the heated seat
driver circuit cavity of the 2-way heated seat back
element wire harness connector and the seat cushion
frame. There should be no continuity. If OK, go to
Step 10. If not OK, replace the faulty seat back cover
trim and element unit.
(10) Check for continuity between the driver seat
heater ground circuit cavity of the 2-way power seat
8N - 12
ELECTRICALLY HEATED SYSTEMS
WJ
DIAGNOSIS AND TESTING (Continued)