Heated Seat System

HEATED SEAT SYSTEM

FRONT SEAT HEATED SEAT SYSTEM DIAGNOSIS

In order to obtain conclusive testing of the front seat heated seat system, the Programmable Communications Interface (PCI) data bus circuit must be checked.

The most reliable, efficient, and accurate means to diagnose the front seat 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 Memory Heated Seat Adjustable Pedal Module (MHSAPM) and both door modules 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 stored fault codes in the MHSAPM and door modules. If the front heated seat lights blink the MHSAPM did not respond to the door modules command to turn on the heated seats.

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 front seat heated seat system is 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, 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. Always, eliminate all other potential problems before attempting to replace the MHSAPM or door modules.

For complete circuit diagrams, refer to Diagrams/Electrical. 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.

PRELIMINARY TEST

Before testing the individual components in the heated seat system, check the following:

- Using the diagnostic scan tool, check the memory heated seat adjustable pedal module (MHSAPM) for any stored fault codes. Record these codes on paper for reference and resolve using the Appropriate Diagnostic Information.
- 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.
- If the heated seat switch backlighting does not light with the ignition switch in the ON position, check the fused ignition switch fuse in the integrated power module. If OK, refer to Heated Seat Switch Diagnosis and Testing. Testing and Inspection
If not OK, repair the shorted circuit or component as required and replace the faulty fuse or repair the open ground circuit as required.
- If 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 integrated power module. If OK, refer to Heated Seat Switch Diagnosis and Testing. Testing and Inspection
If not OK, repair the shorted circuit or component as required and replace the faulty fuse.

2ND ROW HEATED SEAT SYSTEM DIAGNOSIS

The 2nd row heated seat system is capable of performing some self-diagnostics. The following table depicts the various monitored faults which will be reported to the vehicle operator or technician by flashing the individual heated seat switch Light Emitting Diode (LED) indicator lamps. Refer to the HEATED SEAT SYSTEM SELF-DIAGNOSIS table below for failure identification. The left side heated seat switch indicator lamps will flash if a failure occurs in the left rear heated seat, and the right side heated seat switch indicator lamps will flash for a right rear heated seat failure. If a monitored heated seat system fault occurs, the switch indicator lamps will flash at a pulse rate of one-half second on, followed by one-half second off for a duration of one minute after the switch for the faulty heated seat is depressed in either the low or high direction. This process will repeat every time the faulty heated seat switch is actuated until the problem has been corrected.





Diagnostic logic is built into the 2nd row heated seat module to help the person trying to locate the problem by the most efficient means possible. Anytime a problem is suspected, locate the diagnosis and testing procedure for the component in question and follow the steps until the specific problem is located and resolved. Always eliminate problems in this order; sensors, wiring, element, switch, switch wiring, heated seat module. Once the problem is thought to be corrected, verify correct system operation. If the heated seat system is functioning correctly return the vehicle to service.

If a problem could not be verified such as not finding anything wrong when following the diagnostic procedure, 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's/electrical connectors under the seat while testing continuity.