Buick Regal: DTC B392B

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 B392B 00

Seat Lumbar/Bolster Pump

Diagnostic Fault Information

1. The lumbar, bolster and massage functions are inoperative

Circuit/System Description

When a seat lumbar, bolster, or massage function is commanded ON, the seat bolster memory control module applies battery voltage and a low side drive pulse width modulated (PWM) signal through their respective control circuits to the seat lumbar/bolster pump. The logic in the pump interprets this signal and pump runs to inflate the lumbar/bolster bladders until the switch is released.

Conditions for Running the DTC

• Ignition ON.
• The voltage control circuit to the lumbar/bolster pump must be active.

Conditions for Setting the DTC

The seat bolster memory control module detects a short to ground on the lumbar/bolster pump voltage control circuit.

Action Taken When the DTC Sets

All lumbar, bolster, and massage functions are inoperative.

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

• Driver Seat Wiring Schematics
• Passenger Seat Wiring Schematics

Connector End View Reference

Component Connector End View Index

Description and Operation

Lumbar Support Description and Operation (With Memory Seat A44/A45) or Lumbar Support Description and Operation (Without Memory Seat A44/A45)

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 Testing

1. Ignition OFF, all vehicle systems OFF, disconnect the harness connector at the appropriate seat lumbar/bolster pump listed below:

• G31D Seat Lumbar/Bolster Pump - Driver
• G31P Seat Lumbar/Bolster Pump - Passenger

2. Test for less than 10 Ω between the low reference circuit terminal 2 and ground.

• If 10 Ω or greater

1. Ignition OFF.
2. Test for less than 2 Ω in the low reference circuit end to end.
   • If 2 Ω or greater, repair the open/high resistance in the circuit.
   • If less than 2 Ω, replace the K134 Seat Bolster Memory Control Module.

• Go to next step: If less than 10 Ω

3. Connect a test lamp between the control circuit terminal 1 and ground, ignition ON.

4. Verify the test lamp turns ON after pressing and holding the lumbar forward switch.

• If the test lamp remains OFF

1. Ignition OFF, remove the test lamp, disconnect the harness connector at the K134 Seat Bolster Memory Control Module.
2. Test for infinite resistance between the control circuit and ground.
   • If less than infinite resistance, repair the short to ground on the circuit.
   • Go to next step: If infinite resistance
3. Test for less than 2 Ω in the control circuit end to end.
   • If 2 Ω or greater, repair the open/high resistance in the circuit.
   • If less than 2 Ω, replace the K134 Seat Bolster Memory Control Module.

• Go to next step: If the test lamp turns ON

5. Test or replace the G31 Seat Lumbar/Bolster Pump.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

• Front Seat Back Lumbar Replacement (2 Way) or Front Seat Back Lumbar Replacement (GS) or Front Seat Back Lumbar Replacement (4 Way)
• Control Module References for K134D Seat Bolster Memory Control Module - Driver or K134P Seat Bolster Memory Control Module - Passenger replacement, programming and setup

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