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Tahoe / Yukon Service Manual

DTC B1B2D or B1B2E

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 B1B2D 3rd Row Seat Folding Switch - Left DTC B1B2E 3rd Row Seat Folding Switch - Right Symptom Byte Information: Symptom Byte List Circuit/System Description The power folding third row seat system consists of folding seat switches, a control module, a seat back release actuator, a hall-effect position sensor, and the folding seat motor. The third row folding seat switches are located on the D-pillar. Voltage to the switches is supplied through the park enable relay while in a de-energized state. The park enable relay is controlled by the body control module (BCM) through a high side drive control circuit and will be de-energized whenever the ignition is in the accessory or run positions and the transmission is in park. Battery voltage is supplied to the folding seat control module through a 30 A fuse located in the rear body fuse block. When a folding seat switch is pressed, battery voltage is applied through the switch contacts and the signal circuit to the folding seat control module indicating the folding seat request. In response to this signal, the module applies a PWM voltage through the seat back release actuator control circuit energizing the actuator. With the actuator energized and the seat back released, the control module applies battery voltage and ground through the folding seat motor control circuits to the motor. The motor runs to either move the seat back cushion to the folded or unfolded seat position. The control module supplies the hall-effect sensor with a low reference and a signal circuit. The module monitors the voltage from the signal circuit in order to detect a seat stall condition. If the module does not detect seat movement within 400ms, it will cease folding seat operation. Conditions for Running the DTC Ignition ON Conditions for Setting the DTC B1B2D 9E or B1B2E 9E The folding 3rd row seat module detects an stuck switch fault. Action Taken When the DTC Sets The K169 Folding 3rd Row Seat Module will disable all seat functions. Conditions for Clearing the DTC The DTC clears when the diagnostic runs and passes. The history DTC will clear after 40 consecutive fault-free ignition cycles have occurred. Reference Information Schematic Reference Rear Seat Schematics Connector End View Reference Master Electrical Component List Description and Operation Power Seats System Description and Operation Electrical Information Reference Circuit Testing Connector Repairs Testing for Intermittent Conditions and Poor Connections Wiring Repairs Scan Tool Reference Control Module References for scan tool information Circuit/System Verification

  1. Ignition ON.
  2. Verify DTC B1B1A and/or B1B1B is not set. ⇒ If the DTC is set Refer to: DTC B1B1A or B1B1B ⇓ If the DTC is not set
  3. Verify DTC B1B2D and/or B1B2E is not set. ⇒ If the DTC is set Replace the S144B 3rd Row Seat Folding Switch - Rear Compartment. ⇓ If the DTC is not set
  4. A fault is currently not present and may be an intermittent condition. Repair Instructions Perform the Diagnostic Repair Verification after completing the repair.