Heated Seat Inoperative
Heated Seat Inoperative
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (Initial Inspection and Diagnostic Overview) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Initial Inspection and Diagnostic Overview) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Initial Inspection and Diagnostic Overview) provides an overview of each diagnostic category.
Diagnostic Fault Information
Circuit/System Description
Battery positive voltage is supplied at all times to the heated seat module from the HTD SEATS fuse located in the underhood fuse block. Ignition voltage is supplied to the heated seat switch and the heated seat module from the RUN fuse located in the underhood fuse block. When commanded ON, the heated seat module uses this voltage to heat the seat heating elements. The heated seat module and the seat heating elements are grounded through the module ground circuit to G301.
Each time the heated seat switch is pressed, B+ is supplied to the heated seat module through the heated seat signal circuit. The module counts these inputs to determine what level of heat the vehicle operator is commanding. In response to these switch signals, the heated seat module closes it's contacts and applies battery positive voltage through the heated seat element supply voltage circuit to the seat heating elements. When the thermistor inside the seat cushion reaches a certain resistance, the control module open and close the supply voltage in order to maintain that heat level.
Reference Information
Schematic Reference
Heated/Cooled Seat Schematics ([1][2]Electrical Diagrams)
Connector End View Reference
Component Connector End Views (Connector Views)
Description and Operation
Heated Seats Description and Operation (Description and Operation)
Electrical Information Reference
* Circuit Testing (Component Tests and General Diagnostics)
* Connector Repairs (Component Tests and General Diagnostics)
* Testing for Intermittent Conditions and Poor Connections (Component Tests and General Diagnostics)
* Wiring Repairs (Component Tests and General Diagnostics)
Circuit/System Verification
1. Ignition ON, cycle the heated seat switch between the high, medium and low position. The heated seats should operate in all positions.
• If the heated seats do not operate, Refer to Heated Seats Inoperative.
2. Cycle the heated seat switch between the high, medium and low position. The appropriate heated seat indicator should illuminate.
• If either indicator does not illuminate Refer to Headed Seat Indicator Inoperative.
Circuit/System Testing
Heated Seats Inoperative
1. Ignition OFF, disconnect the harness connector at the appropriate heated seat switch.
2. Ignition ON, verify that a test lamp illuminates between the B+ circuit terminal A3 and ground.
• If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.
3. Ignition OFF, connect the harness connector at the heated seat switch. Disconnect the harness connector at the appropriate heated seat module.
4. Test for less than 1 ohm between the ground circuit terminal 14 and ground.
• If greater than the specified range, test the ground circuit for an open/high resistance.
5. Ignition ON, verify that a test lamp illuminates between the B+ circuit terminal 1 and ground.
• If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.
6. Verify that a test lamp illuminates between the B+ circuit terminal 2 and ground.
• If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.
7. Press and release the heated seat switch. Verify that a test lamp illuminates between the control circuit terminal 8 and ground each time the switch is pressed.
• If the test lamp does not illuminate when the switch is pressed, test the signal circuit for a short to ground or an open/high resistance. If the circuit test normal test or replace the switch.
• If the test lamp remains illuminated, test the control circuit for an short to voltage. If the circuit test normal test or replace the switch.
8. Ignition OFF, disconnect the harness connector at the heated seat element - cushion.
9. Test for less than 1 ohm between the ground circuit terminal C and ground.
• If greater than the specified range, test the ground circuit for an open/high resistance.
10. Test for less than 5 ohms between the control terminal D and ground.
• If not within the specified range, test the following circuits for a short to ground or an open/high resistance.
* Control circuit between the heated seat element - cushion terminal D and the heated seat element - back terminal A.
* Heated seat element - back ground circuit terminal B and ground If the circuits test normal, test or replace the heated seat element - back.
11. Connect the harness connector at the heated seat element - cushion.
12. Test for less than 10 ohms between the control circuit terminal 3 and ground.
• If not within the specified range, test the control circuit for a short to ground or open/high resistance. If the circuits test normal, test or replace the Heated Seat Element - Cushion.
13. Test for 1200-10K ohms between the signal circuit terminal 16 and ground.
• If not within the specified range, test the signal circuit for a short to ground or open/high resistance. If the circuits test normal, test or replace the Heated Seat Element - Cushion.
14. If all circuits test normal, replace the heated seat module.
Heated Seats Indicator Circuit Inoperative
1. Ignition OFF, disconnect the harness connector at the appropriate heated seat switch.
2. Test for less than 1 ohm between the ground circuit terminal A2 and ground.
• If greater than the specified range, test the ground circuit for an open/high resistance.
3. Ignition ON, verify a test lamp does not illuminate between the following control circuits and B+.
* Low control circuit terminal A6
* Medium control circuit terminal A7
* High control circuit terminal A8
• If the test lamp illuminates, test the control circuits for a short to ground. If all circuits test normal, test or replace the heated seat control module.
4. Install a test lamp between the appropriate control circuit and B+. Momentarily install a 3A fused jumper between the signal circuit terminal A4 and B+. Each time the signal circuit is momentarily touched to B+ the heated seat module should ground the next level control circuit. Verify the test lamp illuminates.
• If the test lamp does not illuminate, test the appropriate control circuit for an short to voltage or an open/high resistance. If all circuits test normal, test or replace the heated seat control module.
5. If all circuits test normal, replace the heated seat switch.
Repair Instructions
Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.
* Front Seat Heater Switch Replacement (Service and Repair)
* Driver Seat and Passenger Seat Back Cushion Heater Replacement (Driver Seat and Passenger Seat Back Cushion Heater Replacement)
* Front Seat Heater Control Module Replacement (Service and Repair)
* Driver Seat Cushion Heater Replacement (Driver Seat Cushion Heater Replacement)
* Passenger Seat Cushion Heater Replacement (Passenger Seat Cushion Heater Replacement)