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 |
|---|---|---|---|---|
Left rear heated seat back element supply voltage | B2508 02 | B1935 0C, B1935 0D | B2345 00, B2508 01 | B1935 0B, B1935 0E |
Left rear heated seat back element control | B2345 00, B2508 02 | B1935 0C, B1935 0D | B2345 00, B2508 01 | B1935 0B, B1935 0E |
Left rear heated seat back temperature sensor signal | B2435 02 | B1935 04, B1935 1F, B2435 0D | B1935 04, B1935 1F, B2435 0D | B1935 0A, B2345 13, B2345 42, B2345 4B |
Left rear heated seat back temperature sensor low reference | -- | B1935 04, B1935 1F, B2435 0D | -- | B2345 13, B2345 42, B2345 4B |
Left rear heated seat cushion element supply voltage | B2508 02 | B2425 0C, B2425 0D | B2345 00, B2508 01 | B2425 0B, B2425 0E |
Left rear heated seat cushion element control | B2345 00, B2508 02 | B2425 0C, B2425 0D | B2345 00, B2508 01 | B2425 0B, B2425 0E |
Left rear heated seat cushion temperature sensor signal | B1925 02, B2425 1F | B1925 05, B2425 04, B2425 1F | B1925 05, B2425 04, B2425 1F | B2345 13, B2345 42, B2345 4B, B2425 0A |
Left rear heated seat cushion temperature sensor low reference | -- | B1925 05, B2425 04, B2425 1F | -- | B2345 13, B2345 42, B2345 4B |
Right rear heated seat back element supply voltage | B2508 02 | B2180 0C, B2180 0D | B2345 00, B2508 01 | B2180 0B, B2180 0E |
Right rear heated seat back element control | B2345 00, B2508 02 | B2180 0C, B2180 0D | B2345 00, B2508 01 | B2180 0B, B2180 0E |
Right rear heated seat back temperature sensor signal | B2440 02 | B2180 04, B2180 1F, B2440 05 | B2180 04, B2180 1F, B2440 05 | B2180 0A, B2345 13, B2345 42, B2345 4B |
Right rear heated seat back temperature sensor low reference | -- | B2180 04, B2180 1F, B2440 05 | -- | B2345 13, B2345 42, B2345 4B |
Right rear heated seat cushion element supply voltage | B2508 02 | B2430 0C, B2430 0D | B2345 00, B2508 01 | B2430 0B, B2430 0E |
Right rear heated seat cushion element control | B2345 00, B2508 02 | B2430 0C, B2430 0D | B2345 00, B2508 01 | B2430 0B, B2430 0E |
Right rear heated seat cushion temperature sensor signal | B2170 02, B2430 1F | B2430 04, B2430 1F, B2170 05 | B2430 04, B2430 1F, B2170 05 | B2345 13, B2345 42, B2345 4B, B2430 0A |
Right rear heated seat cushion temperature sensor low reference | -- | B2430 04, B2430 1F, B2170 05 | -- | B2345 13, B2345 42, B2345 4B |
Circuit/System Description
The left and right rear heated seat heating elements are controlled by a common high current relay internal to the rear heated seat module (RHSM) and the low side by individual element control circuits. The RHSM 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 RHSM 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 RHSM must be powered.
Conditions for Setting the DTC
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.
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.
Action Taken When the DTC Sets
The heated seat function for the left and right rear passenger seats will be disabled.
Conditions for Clearing the DTC
| • | The current DTC will clear and set to history 3 seconds after the reference voltage returns to the normal operating range 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
Connector End View Reference
Heated/Cooled Seat Component Views
Electrical Information Reference
Scan Tool Reference
Circuit/System Testing
- Ignition OFF, disconnect the C1 harness connector at the RHSM.
- Test for infinite resistance between the supply voltage circuit terminal 3 and ground.
- Test for infinite resistance between the supply voltage circuit terminal 6 and ground.
- Ignition ON, verify that a test lamp does not illuminate between the supply voltage circuit terminal 3 and ground.
- Verify that a test lamp does not illuminate between the supply voltage circuit terminal 6 and ground.
- If all circuits test normal, replace the RHSM.
| ⇒ | If not the specified value, test the supply voltage circuit and the control circuits listed below for a short to ground. |
| • | Left rear seat cushion element terminal 5 |
| • | Left rear seat back element terminal 1 |
| ⇒ | If not the specified value, test the supply voltage circuit and the control circuits listed below for a short to ground. |
| • | Right rear seat cushion element terminal 2 |
| • | Right rear seat back element terminal 4 |
| ⇒ | If the test lamp illuminates, test the supply voltage circuit and the control circuits listed below for a short to voltage. |
| • | Left rear seat cushion element terminal 5 |
| • | Left rear seat back element terminal 1 |
| ⇒ | If the test lamp illuminates, test the supply voltage circuit and the control circuits listed below for a short to voltage. |
| • | Right rear seat cushion element terminal 2 |
| • | Right rear seat back element terminal 4 |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
| • | Control Module References for RHSM replacement, setup, and programming |
