Seat Temperature Element: Testing and Inspection
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 to the heated seat module from the HTD SEATS/BCK UP and HTD/SEAT fuses 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 and G302.
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 control module sends a B+ signal to illuminate the appropriate heated seat indicator. The heated seat module then closes it's contacts and applies B+ 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)
Scan Tool Reference
Control Module References (Programming and Relearning) for scan tool information
Circuit/System Verification
1. Ignition ON, cycle the heated seat switch between the high and low position. The heated seats should operate in both positions.
• If the heated seats do not operate, refer to Heated Seats Inoperative.
2. Cycle the heated seat switch between the high 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 control module.
2. Test for less than 1 ohm between the ground circuit terminal 2 and ground.
• If greater than the specified range, test the ground circuit for an open/high resistance.
3. Ignition ON, verify that a test lamp illuminates between the B+ circuit terminal 10 and ground.
• If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.
4. Verify that a test lamp illuminates between the ignition circuit terminal 3 and ground.
• If the test lamp does not illuminate, test the ignition circuit for a short to ground or an open/high resistance.
5. Install a test lamp between the control circuit terminal 9 and ground
6. Press and release the heated seat switch. Verify that a test lamp illuminates each time the switch is pressed.
• If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit test normal, replace the HVAC control module.
• If the test lamp is always ON, test the control circuit for an short to voltage. If the circuit test normal replace the HVAC control module.
7. Ignition OFF, connect the harness connector at the heated seat module. Disconnect the harness connector at the heated seat element - cushion.
8. Test for less than 1 ohm between the ground circuit terminal D and ground.
• If greater than the specified range, test the ground circuit for an open/high resistance. If the circuit test normal, replace the heated seat control module.
9. Ignition ON, test for 4.8-5.2 volts between the signal circuit terminal C and ground.
• If less than specified range, test the signal circuit for a short to ground or an open/high resistance. If the circuit test normal, replace the heated seat control module.
• If greater than specified range, test the signal circuit for an short to voltage. If the circuit tests normal, replace the heated seat control module.
10. Test for 1200-10K ohms across the temperature sensor terminals in the heated seat - cushion.
• If not within the specified range, test or replace the heated seat element - cushion.
11. Ignition OFF disconnect the harness connector at the heated seat element - back.
12. Test for less than 1 ohm between the ground circuit terminal B and ground.
• If greater than the specified range, test the ground circuit for an open/high resistance.
13. Connect the harness connector at the heated seat element - back.
14. Test for 5-10 ohms between the control circuit terminal B of the heated seat element - cushion harness connector and ground.
• If not within the specified range, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, test or replace the heated seat element - back.
15. Connect the harness connector at the heated seat element - cushion. Disconnect the harness connector at the heated seat control module.
16. Test for 10-20 ohms between the control circuit terminal 8 and ground.
• If not within the specified range, test the control circuit for a short to ground or open/high resistance. If the circuit tests normal, test or replace the heated seat element - cushion.
17. If all circuits test normal, replace the heated seat control module.
Heated Seats Indicator Circuit Inoperative
1. Ignition OFF, disconnect the harness connector at the heated seat control module.
2. Install a 3A fused jumper wire between the control circuit terminal 4 and the B+. Verify the heated seat high heat indicator is illuminated.
• If the indicator does not illuminate, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the HVAC control module.
3. Install a 3A fused jumper wire between the control circuit terminal 1 and the B+. Verify the heated seat low heat indicator is illuminated.
• If the indicator does not illuminate, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the HVAC control module.
4. If all circuits test normal, replace the heated seat control module.
Repair Instructions
Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.
* 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)
* Front Seat Heater Element Replacement (Front Seat Heater Element Replacement)
* Heater and Air Conditioning Control Replacement (Service and Repair)