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 |
|---|---|---|---|---|
B+, MSM Terminal 5 X3 | 1, B2425 0D, B2430 0D | 1, B2425 0D, B2430 0D | -- | -- |
Driver Heated Seat Element Supply Voltage | B2508 02 | B2425 0D | B2508 01 | B2425 0E |
Driver Heated Seat Element Control | B2508 02 | B2425 0D | B2508 01 | B2425 0E |
Driver Heated Seat Temperature Sensor Signal | B1925 02 | B1925 05 | B1925 05 | B2345 13, B2345 42, B2345 4B |
Driver Heated Seat Temperature Sensor Low Reference | -- | B1925 05 | -- | B2345 13, B2345 42, B2345 4B |
Passenger Heated Seat Element Supply Voltage | B2508 02 | B2430 0D | B2508 01 | B2430 0E |
Passenger Heated Seat Element Control | B2508 02 | B2430 0D | B2508 01 | B2430 0E |
Passenger Heated Seat Temperature Sensor Signal | B2170 02 | B2170 05 | B2170 05 | B2345 13, B2345 42, B2345 4B |
Passenger Heated Seat Temperature Sensor Low Reference | -- | B2170 05 | -- | B2345 13, B2345 42, B2345 4B |
1. Power seats inoperative | ||||
Circuit/System Description
The driver and passenger seat heating elements are controlled by a common high current relay internal to the memory seat module (MSM) and by individual low side 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 voltage. Once the module verifies that it is not closing to a shorted heating element, it allows for heated seat operation. The module will then continue to monitor the heating elements for a shorted circuit.
Conditions for Running the DTC
The MSM must be powered.
Conditions for Setting the DTC
B2508 01
The MSM detects a short to voltage on the heater element supply voltage circuit or control circuit.
B2508 02
The MSM detects a short to ground on the heater 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 and set a history code 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/Vented Seat 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 6 X1 and ground.
- Test for infinite resistance 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.
- Verify that a test lamp does not illuminate between the control circuit terminal 14 X1 and ground.
- If all circuits test normal, replace the MSM.
| ⇒ | If less than the specified range, test the control circuits for a short to ground. |
| ⇒ | If less than the specified range, test the control circuits for a short to ground. |
| ⇒ | If the test lamp illuminates, test the control circuits for a short to voltage. |
| ⇒ | If the test lamp illuminates, test the control circuits for a short to voltage. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
| • | Control Module References for MSM replacement, setup, and programming |
