B2509
DTC B2508 or B2509Diagnostic Instructions
^ Perform the [Diagnostic System Check - Vehicle Diagnostic Information] prior to using this diagnostic procedure. Diagnostic System Check - Vehicle Diagnostic Information
^ Review [Strategy Based Diagnosis] for an overview of the diagnostic approach. Strategy Based Diagnosis
^ [Diagnostic Procedure Instructions - Vehicle Diagnostic Information] provides an overview of each diagnostic category. Diagnostic Procedure Instructions - Vehicle Diagnostic Information
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 driver and passenger seat heating elements are controlled by a common high current relay internal to the heated seat module and by individual low side element control circuits. The heated seat module 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 heated seat module 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 heated seat module must be powered.
Conditions for Setting the DTC
B2508 01
The heated seat module detects a short to voltage on the heater element supply voltage circuit or control circuit.
B2508 02
The heated seat module detects a short to ground for 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.
Circuit/System Testing
1. Ignition OFF, disconnect the (C1) harness connector at the heated seat module.
2. Test for infinite resistance between the supply voltage circuit terminal 3 and ground.
^ If less than the specified range, test the element supply voltage circuit and control circuit for a short to ground.
3. Test for infinite resistance between the supply voltage circuit terminal 6 and ground.
^ If less than the specified range, test the element supply voltage circuit and control circuit for a short to ground.
4. Ignition ON, verify that a test lamp does not illuminate between the supply voltage circuit terminal 3 and ground.
^ If the test lamp illuminates, test the element supply voltage circuit and control circuit for a short to voltage.
5. Verify that a test lamp does not illuminate between the supply voltage circuit terminal 6 and ground.
^ If the test lamp illuminates, test the element supply voltage circuit and control circuit for a short to voltage.
6. If all circuits test normal, replace the heated seat module.
Repair Instructions
Perform the [Diagnostic Repair Verification - Vehicle Diagnostic Information] after completing the diagnostic procedure. Diagnostic Repair Verification - Vehicle Diagnostic Information
^ [Driver Seat Back Cushion Heater and Passenger Seat Back Cushion Heater Replacement (Non Fold Flat)] [Driver Seat Back Cushion Heater and Passenger Seat Back Cushion Heater Replacement (Fold Flat)]
^ [Driver Seat Cushion Heater and Passenger Seat Cushion Heater Replacement]
^ [Control Module References] for heated seat control module replacement, setup, and programming Programming and Relearning