Diagnostic Instructions
| • | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. |
| • | Review Strategy Based Diagnosis for an overview of the diagnostic approach. |
| • | Diagnostic Procedure Instructions provides an overview of each diagnostic category. |
DTC Descriptors
DTC B2508 01: Seat Heater Relay Circuit Short to BatteryDTC B2508 02: Seat Heater Relay Circuit Short to Ground
Diagnostic Fault Information
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
|---|---|---|---|---|
Driver Heated Seat Back Element Supply Voltage | B2508 02 | B1935 0D | B2508 01 | B1935 0E |
Driver Heated Seat Back Element Control | B2508 02 | B1935 0D | B2508 01 | B1935 0E |
Driver Heated Seat Back Temperature Sensor Signal | B2435 02 | B2435 05 | B2435 05 | B2345 13, B2345 42, B2345 4B |
Driver Heated Seat Back Temperature Sensor Low Reference | -- | B2435 05 | -- | B2345 13, B2345 42, B2345 4B |
Driver Heated Seat Cushion Element Supply Voltage | B2508 02 | B2425 0D | B2508 01 | B2425 0E |
Driver Heated Seat Cushion Element Control | B2508 02 | B2425 0D | B2508 01 | B2425 0E |
Driver Heated Seat Cushion Temperature Sensor Signal | B1925 02 | B1925 05 | B1925 05 | B2345 13, B2345 42, B2345 4B |
Driver Heated Seat Cushion Temperature Sensor Low Reference | -- | B1925 05 | -- | B2345 13, B2345 42, B2345 4B |
Passenger Heated Seat Back Element Supply Voltage | B2508 02 | B2180 0D | B2508 01 | B2180 0E |
Passenger Heated Seat Back Element Control | B2508 02 | B2180 0D | B2508 01 | B2180 0E |
Passenger Heated Seat Back Temperature Sensor Signal | B2440 02 | B2440 05 | B2440 05 | B2345 13, B2345 42, B2345 4B |
Passenger Heated Seat Back Temperature Sensor Low Reference | -- | B2440 05 | -- | B2345 13, B2345 42, B2345 4B |
Passenger Heated Seat Cushion Element Supply Voltage | B2508 02 | B2430 0D | B2508 01 | B2430 0E |
Passenger Heated Seat Cushion Element Control | B2508 02 | B2430 0D | B2508 01 | B2430 0E |
Passenger Heated Seat Cushion Temperature Sensor Signal | B2170 02 | B2170 05 | B2170 05 | B2345 13, B2345 42, B2345 4B |
Passenger Heated Seat Cushion Temperature Sensor Low Reference | -- | B2170 05 | -- | B2345 13, B2345 42, B2345 4B |
Circuit/System Description
The driver and passenger heated seat heating elements are controlled by a common high current relay internal to the memory seat module (MSM) and the low side by individual element control circuits. The MSM connects the heated seat heater element supply voltage circuits for both seats to a common reference point. This reference point is biased to approximately 2.0 volts. Before the MSM will allow heated seat operation, it checks to see if this reference voltage is shorted to ground or battery voltage. Once the module 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 MSM must be powered.
Conditions for Setting the DTC
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.
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.
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 will clear set the code to history, 3 seconds after the reference voltage returns to normal operating range and the ignition is cycled 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
Connector End View Reference
Description and Operation
Heated Seats Description and Operation
Electrical Information Reference
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Testing
- Ignition OFF, disconnect the X1, X4 harness connectors at the MSM.
- Test for infinite resistance between the control circuit terminal 14 X1 and ground.
- Test for infinite resistance between the control circuit terminal 6 X1 and ground.
- Ignition ON, verify that a test lamp does not illuminate between the control circuit terminal 14 X1 and ground.
- Ignition ON, verify that a test lamp does not illuminate between the control circuit terminal 6 X1 and ground.
- If all circuits test normal, replace the MSM.
| ⇒ | If not the specified value, test the control circuits listed below for a short to ground. |
| • | Driver seat cushion and back element terminal 14 X1 |
| • | Driver seat cushion element terminal 11 X1 |
| • | Driver seat back element terminal 1 X1 |
| ⇒ | If not the specified value, test the control circuits listed below for a short to ground. |
| • | Passenger seat cushion and back element terminal 6 X1 |
| • | Passenger seat cushion element terminal 14 X4 |
| • | Passenger seat back element terminal 4 X1 |
| ⇒ | If the test lamp illuminates, test the control circuits listed below for a short to voltage. |
| • | Driver seat cushion and back element terminal 14 X1 |
| • | Driver seat cushion element terminal 11 X1 |
| • | Driver seat back element terminal 1 X1 |
| ⇒ | If the test lamp illuminates, test the control circuits listed below for a short to voltage. |
| • | Passenger seat cushion and back element terminal 6 X1 |
| • | Passenger seat cushion element terminal 14 X4 |
| • | Passenger seat back element terminal 4 X1 |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
| • | Control Module References for MSM replacement, programming and setup |
