B2509 (Front Seat)

DTC B2508 or B2509 (Front Seat)

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle (Diagnostic System Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Strategy Based Diagnosis) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Diagnostic Procedure Instructions)provides an overview of each diagnostic category.



DTC Descriptors
DTC B2508 01
- Seat Heater Relay Circuit Shorted to Battery or Open

DTC B2508 02
- Seat Heater Relay Circuit Shorted to Ground




Diagnostic Fault Information






Circuit/System Description

The front seat heating elements are controlled by a common high current relay internal to the memory seat module (MSM) and on the low side by individual element control circuits. Before the MSM 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 module verifies that it is not closing into 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 memory seat module must be powered.


Conditions for Setting the DTC

B2508 02

Before the heated seats are activated, the MSM 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 MSM 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 the driver and passenger 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 ([1][2]Electrical Diagrams)
Connector End View Reference

Component Connector End Views (Component Connector End 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

Programming and Relearning (Programming and Relearning)for Scan Tool Information


Circuit/System Testing

1. Ignition OFF, disconnect the MSM connectors X1 and X4.
2. Test for infinite resistance between the left seat heating element supply voltage circuit terminal 14 and ground.

• If less than infinite, test the supply voltage circuit and the seat cushion and seat back heating element control circuits for a short to ground.

3. Ignition ON, verify that a test lamp does not illuminate between the supply voltage circuit terminal 14 and ground.

• If the test lamp illuminates, test the supply voltage circuit and the seat cushion and seat back heating element control circuits for a short to voltage.

4. Test for infinite resistance between the right seat heating element supply voltage circuit terminal 6 and ground.

• If less than infinite, test the supply voltage circuit and the seat cushion and seat back heating element control circuits for a short to ground.

5. Ignition ON, verify that a test lamp does not illuminate between the supply voltage circuit terminal 6 and ground.

• If the test lamp illuminates, test the supply voltage circuit and the seat cushion and seat back heating element control circuits for a short to voltage.

6. If all circuits test normal, replace the MSM.



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)
* Driver Seat and Passenger Seat Cushion Heater Replacement (Driver Seat and Passenger Seat Cushion Heater Replacement)
* Programming and Relearning (Programming and Relearning)for the MSM replacement, setup, and programming