Replacement (Tahoe with HP2) ()Driver or Passenger Seat Back Cushion Heater Replacement (without HP2) ()
* Driver or Passenger Seat Cushion Heater Replacement (without HP2) ()Driver or Passenger Seat Cushion Heater Replacement (with HP2)
()
* Control Module References (See: Testing and Inspection/Programming and Relearning) for the HSM replacement, setup, and programming
Rear Seat
DTC B2508 or B2509 (Rear Seat)
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic System
Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Strategy Based Diagnosis) for an
overview of the diagnostic approach.
* Diagnostic Procedure Instructions (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic Procedure
Instructions) provides an overview of each diagnostic category.
DTC Descriptors
DTC B2508 01
- Seat Heater Relay Circuit Short to Battery
DTC B2508 02
- Seat Heater Relay Circuit Short to Ground
Diagnostic Fault Information
Circuit/System Description
The rear seat heating elements are controlled by a common high current relay internal to the rear heated seat module (RHSM) and on the low side by
individual element control circuits. The RHSM connects the seat heater element supply voltage circuits to a common reference point. This reference
point is biased to approximately 2.5 V. Before the RHSM 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 RHSM 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 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.
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
