Seat Heating and Cooling
DTC B2508 or B2509 (Rear Heated Seat Module)
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (with HP2) (Initial Inspection and Diagnostic Overview)Diagnostic System Check - Vehicle (without HP2) (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.
DTC Descriptors
DTC B2508 01
- Seat Heater Relay Circuit Short to Battery
DTC B2508 02
- Seat Heater Relay Circuit Short to Ground
Diagnostic Fault Information
Circuit/System Description
The rear seat heating elements are controlled by a common high current relay internal to the rear heated seat module (RHSM) and on the low side by individual element control circuits. The RHSM connects the seat heater element supply voltage circuits to a common reference point. This reference point is biased to approximately 2.0 volts. Before the RHSM will allow heated seat operation, it checks to see if the heating element supply voltage circuits and control circuits are shorted to ground or battery voltage. Once the RHSM verifies that it is not closing to a shorted heating element, it allows heated seat operation. After which it continues to monitor for a shorted circuit.
Conditions for Running the DTC
The RHSM must be powered.
Conditions for Setting the DTC
B2508 02
Before the heated seats are activated, the RHSM detects a short to ground on the seat heating element supply voltage circuit or control circuit.
B2508 01
Before the heated seats are activated, the RHSM detects a short to battery voltage on the seat heating element supply voltage circuit or control circuit.
Action Taken When the DTC Sets
The heated seat function for both seats will be disabled.
Conditions for Clearing the DTC
* The current DTC clears when the malfunction is no longer present and the power mode changes to OFF then back to ACC or RUN.
* The history DTC will clear after 50 consecutive fault-free ignition cycles have occurred.
Reference Information
Schematic Reference
Heated/Cooled Seat Schematics (Electrical Diagrams)
Connector End View Reference
Component Connector End Views (Connector Views)
Description and Operation
Heated Seats Description and Operation (KA1) (Heated Seats Description and Operation (KA1))Heated Seats Description and Operation (KA6) (Heated Seats Description and Operation (KA6))
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 Testing
1. Ignition OFF, disconnect the X1 harness connector at the RHSM.
2. Test for infinite resistance between the control circuit terminal 3 and ground.
• If not the specified value, test the control circuits listed below for a short to ground:
* Left rear seat cushion terminal 3
* Left rear seat cushion terminal 5
3. Test for infinite resistance between the control circuit terminal 6 and ground.
• If not the specified value, test the control circuits listed below for a short to ground:
* Right rear seat cushion terminal 6
* Right rear seat cushion terminal 2
4. Ignition ON, verify that a test lamp does not illuminate between the control circuit terminal 3 and ground.
• If the test lamp illuminates, test the control circuits listed below for a short to voltage:
* Left rear seat cushion terminal 3
* Left rear seat cushion terminal 5
5. Verify that a test lamp does not illuminate between the control circuit terminal 6 and ground.
• If the test lamp illuminates, test the control circuits listed below for a short to voltage:
* Right rear seat cushion terminal 6
* Right rear seat cushion terminal 2
6. If all circuits test normal, replace the RHSM.
Repair Instructions
Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.
* Rear Seat Cushion Heater Replacement (Rear Seat Cushion Heater Replacement)
* Control Module References (Programming and Relearning)for the RHSM replacement, setup, and programming