Grand Cherokee 2WD V6-3.7L (2008)
Seat Heater Control Module: Testing and Inspection
HEATED SEAT MODULE
PRELIMINARY CHECKS
NOTE: Vehicles equipped with the heated seat option utilize a low voltage cut-off feature. This feature turns off power to the heated seat
system anytime vehicle voltage is below 11.7V or above 15.5V. Be certain to check the vehicle electrical system for proper voltage anytime the
power seat system appears inoperative.
Before testing the individual components in the heated seat system, check the following:
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Check the vehicles battery open-circuit voltage and charging system performance. If the vehicle's electrical system is defective or weak it may not
be suppling sufficient energy to operate the heated seat system.
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Using a diagnostic scan tool, check for any heated seat system related Diagnostic Trouble Codes (DTCs). Record these codes on paper for
reference and resolve using the Appropriate Diagnostic Information.
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If the front heated seat system functions properly but the heated seat switch HI/LO LED indicators do not light with the ignition switch in the ON
position and the heated seat switch in the low or high position, check the fused ignition switch fuse in the power distribution center. If OK, replace
the HVAC control assembly. If not OK, repair the shorted circuit or component as required and replace the inoperative fuse.
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If the 2nd row heated seat system functions properly but the heated seat switch HI/LO LED indicators do not light with the ignition switch in the
ON position and the heated seat switch in the low or high position, check the fused ignition switch fuse in the power distribution center. If OK,
replace the suspect heated seat switch. If not OK, repair the shorted circuit or component as required and replace the inoperative fuse.
SCAN TOOL DIAGNOSIS
The most reliable, efficient, and accurate means to diagnose the heated seat system requires the use of a diagnostic scan tool and the Appropriate
Diagnostic Information. The diagnostic scan tool can provide vital information to the technician trying to find a problem with the heated seat system.
Diagnostic logic is built into the Heated Seat Module and Instrument Cluster to help locate the problem by the most efficient means possible. Anytime a
problem is suspected, a diagnostic scan tool should be obtained and used to retrieve any heated seat system related stored fault codes.
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 code, locate
the diagnostic procedure for this code in the Appropriate Diagnostic Information and follow the flow chart until the specific problem is located and
resolved. Once the problem is thought to be corrected, erase the stored fault code using the diagnostic scan tool and verify correct system operation. If
the heated seat system is functioning correctly, verify that there are no other stored codes and return the vehicle to service.
If the fault code could not be verified, this is a good indication that an INTERMITTENT problem may be present. You must then attempt to find the
intermittent problem, such as moving the heating element within the seat while testing continuity or wiggling the wire harness/electrical connectors under
the seat while testing continuity.
For complete circuit diagrams, refer to the appropriate wiring information. The wiring information includes wiring diagrams, proper wire and connector
repair procedures, details of wire harness routing and retention, connector pin-out information and location views for the various wire harness
connectors, splices and grounds.
