Buick Regal: DTC B1480

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 Descriptor

DTC B1480 02

Battery Rundown Protection Circuit Short to Ground

Diagnostic Fault Information

1. Courtesy Lamps Malfunction

Circuit/System Description

The body control module (BCM) supplies battery voltage to the front and rear reading lamps, left and right sunshade lamps, center console compartment lamp, and instrument panel compartment lamp via the courtesy lamp control circuit. When the instrument panel compartment, center console armrest, or a sunshade mirror is opened, the switch contacts close allowing battery voltage to flow illuminating the respective lamps. The front and rear reading lamps are controlled by individual switches that are activated by the occupants when additional cabin lighting is required. In the event that any of these courtesy lamps were to remain illuminated for more than 10 min with the ignition switch in the OFF position, the BCM will deactivate the courtesy lamp control circuit to prevent total battery discharge.

Conditions for Running the DTC

Battery voltage must be between 9 - 16 V.

Conditions for Setting the DTC

The BCM detects a short to ground in the courtesy lamps control circuit terminal 3 X7.

Actions Taken When the DTC Sets

• The BCM will disable the control circuit and all lamps controlled by the courtesy lamps control circuit terminal 3 X7 will be inoperative.
• Dome lamps inoperative.

Conditions for Clearing the DTC

• The condition responsible for setting the DTC no longer exists.
• A history DTC will clear once 100 consecutive malfunction-free ignition cycles have occurred.

Reference Information

Schematic Reference

• Interior Lights Wiring Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

Interior Lighting Systems 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 Testing

1. Ignition OFF, disconnect the harness connectors at the components listed below.

• A3L Sunshade - Left
• A3R Sunshade - Right
• A98 Front Overhead Console Assembly
• E27 Instrument Panel Compartment Lamp
• E37J Dome/Reading Lamps - Left Roof Rail (C3U)
• E37H Dome/Reading Lamps - Right Roof Rail (C3U)
• E37R Dome/Reading Lamps - Rear (C93-C3U)

2. Connect a test lamp between the appropriate control circuit terminal listed below and ground, ignition ON.

• A3L Sunshade - Left terminal A
• A3R Sunshade - Right terminal A
• A98 Front Overhead Console Assembly terminal 7
• E27 Instrument Panel Compartment Lamp terminal 1
• E37J Dome/Reading Lamps - Left Roof Rail terminal 1 (C3U)
• E37H Dome/Reading Lamps - Right Roof Rail terminal 1 (C3U)
• E37R Dome/Reading Lamps - Rear terminal 4 (C93-C3U)

3. Verify the test lamp turns ON and OFF when commanding the Inadvertent Load ON and OFF with a scan tool.

• If the test lamp is always OFF

1. Ignition OFF, disconnect the X7 harness connector at the K9 Body 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 K9 Body Control Module.

• If the test lamp is always ON

1. Ignition OFF, disconnect the X7 harness connector at the K9 Body Control Module, ignition ON.
2. Test for less than 1 V between the control circuit terminal and ground.
   • If 1 V or greater, repair the short to voltage on the circuit.
   • If less than 1 V, replace the K9 Body Control Module.

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

4. Test or replace the courtesy lamp.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

• Center Reading Lamp Replacement (without Sunroof)
• Instrument Panel Compartment Lamp Replacement
• Rear Seat Position Center Reading Lamp Replacement (with Sunroof)
• Roof Console Replacement
• Sunshade Replacement
• Control Module References for BCM replacement, programming, and setup

READ NEXT: