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Contents Wiring diagrams Section: Exterior Lights All sections

Lighting System Buick Regal V

Exterior Lights 47 illustrations ~28382 words

Fastener Tightening Specifications

ApplicationSpecification
MetricEnglish
Brake Pedal Position Sensor Screw2 N.m18 lb in
Front Fog Lamp Screw2.5 N.m22 lb in
Headlamp Leveling Front Suspension Height Sensor Exciter Plate Bolt2.5 N.m22 lb in
Headlamp Screw to Front Fender Lower2.5 N.m22 lb in
Headlamp Screw to Front Fender Upper Bracket2.5 N.m22 lb in
Headlamp Screw to Headlamp Mounting Panel Bracket2.5 N.m22 lb in
Headlamp Screw to Headlamp Mounting Outer Panel Bracket2.5 N.m22 lb in
Headlamp Switch Retaining Screw2 N.m18 lb in
Tail Lamp Nut2.5 N.m22 lb in

Fastener Tightening Specifications

Scheme 1

Scheme 1: Headlamp Controls Wiring Schematics
Scheme 1: Headlamp Controls Wiring Schematics

Scheme 2

Scheme 2: Lamps (T4A) Wiring Schematics
Scheme 2: Lamps (T4A) Wiring Schematics

Scheme 3

Scheme 3: Lamps (T4F) Wiring Schematics
Scheme 3: Lamps (T4F) Wiring Schematics

Scheme 4

Scheme 4: Fog Lights Wiring Schematics
Scheme 4: Fog Lights Wiring Schematics

Scheme 5

Scheme 5: Controls and Indicators Wiring Schematics
Scheme 5: Controls and Indicators Wiring Schematics

Scheme 6

Scheme 6: Front Lamps (T4A) Wiring Schematics
Scheme 6: Front Lamps (T4A) Wiring Schematics

Scheme 7

Scheme 7: Front Lamps (T4F) Wiring Schematics
Scheme 7: Front Lamps (T4F) Wiring Schematics

Scheme 8

Scheme 8: License, Stop, Tail, and Rear Turn Signal Lamps Wiring Schematics
Scheme 8: License, Stop, Tail, and Rear Turn Signal Lamps Wiring Schematics

Scheme 9

Scheme 9: Backup Lamps Wiring Schematics
Scheme 9: Backup Lamps Wiring Schematics

Scheme 10

Scheme 10: Controls and Door Pocket Lamps Wiring Schematics
Scheme 10: Controls and Door Pocket Lamps Wiring Schematics

Scheme 11

Scheme 11: Courtesy Lamps Wiring Schematics
Scheme 11: Courtesy Lamps Wiring Schematics

Scheme 12

Scheme 12: Overhead and Instrument Panel Compartment Lamps Wiring Schematics
Scheme 12: Overhead and Instrument Panel Compartment Lamps Wiring Schematics

Scheme 13

Scheme 13: Controls, Doors, and Overhead Lamps Wiring Schematics
Scheme 13: Controls, Doors, and Overhead Lamps Wiring Schematics

Scheme 14

Scheme 14: Instrument Panel and Floor Console Lamps Wiring Schematics
Scheme 14: Instrument Panel and Floor Console Lamps Wiring Schematics

Diagnostic Code Index

DTCDescription
DTC B096ADTC B096A 02 Hazard Lamps Switch Backlight Circuit Short to Ground
DTC B1405, B1529, or B257BDTC B1405 02 Control Module Voltage Reference Output 2 Circuit Short to Ground DTC B1405 03 Control Module Voltage Reference Output 2 Circuit Low Voltage DTC B1405 07 Control Module Voltage Reference Output 2 Circuit High Voltage DTC B1529 03 Control Module Voltage Reference Output 5 Circuit Low Voltage DTC B1529 07 Control Module Voltage Reference Output 5 Circuit High Voltage DTC B257B 03 Lighting Control Switch Signal Low Voltage DTC B257B 07 Lighting Control Switch Signal High Voltage
DTC B1480DTC B1480 02 Battery Rundown Protection Circuit Short to Ground
DTC B2530DTC B2530 01 Front Fog Lamps Control Circuit Short to Battery DTC B2530 02 Front Fog Lamps Control Circuit Short to Ground DTC B2530 04 Front Fog Lamps Control Circuit Open
DTC B2545DTC B2545 02 Backup Lamps Circuit Short to Ground DTC B2545 04 Backup Lamps Circuit Open
DTC B255DDTC B255D 02 Passenger Compartment Lamp Control 2 Circuit Short to Ground
DTC B2560DTC B2560 02 Cargo Lamp Control Circuit Short to Ground
DTC B256ADTC B256A 04 Liftgate Lamp Control Circuit Open
DTC B2570DTC B2570 01 Trunk Lamp Control Circuit Short to Battery DTC B2570 02 Trunk Lamp Control Circuit Short to Ground DTC B2570 04 Trunk Lamp Control Circuit Open
DTC B2575 or B2699DTC B2575 02 Headlamps Control Circuit Short to Ground DTC B2575 04 Headlamps Control Circuit Open DTC B2699 02 Right Headlamp Control Circuit Short to Ground DTC B2699 04 Right Headlamp Control Circuit Open
DTC B257ADTC B257A 00 Headlamp Switch Input Signals Correlation Malfunction
DTC B2580DTC B2580 02 High Beam Control Circuit Short to Ground
DTC B2585 or B3867DTC B2585 01 Left Park Lamp Control Circuit Short to Battery DTC B2585 02 Left Park Lamp Control Circuit Short to Ground DTC B2585 04 Left Park Lamp Control Circuit Open DTC B3867 01 Right Park Lamp Control Circuit Short to Battery DTC B3867 02 Right Park Lamp Control Circuit Short to Ground DTC B3867 04 Right Park Lamp Control Circuit Open
DTC B258ADTC B258A 01 Low Beam Control Circuit Short to Battery DTC B258A 02 Low Beam Control Circuit Short to Ground DTC B258A 04 Low Beam Control Circuit Open
DTC B2610DTC B2610 02 Passenger Compartment Dimming 1 Circuit Short to Ground
DTC B2615DTC B2615 02 Passenger Compartment Dimming 2 Circuit Short to Ground DTC B2615 04 Passenger Compartment Dimming 2 Circuit Open
DTC B2625DTC B2625 02 Display Dimming Pulse Width Modulation Output Circuit Short to Ground
DTC B263ADTC B263A 02 Exterior Illumination Lamp Circuit Short to Ground
DTC B2645DTC B2645 03 Ambient Light Sensor Circuit Low Voltage DTC B2645 07 Ambient Light Sensor Circuit High Voltage
DTC B2652DTC B2652 02 Passenger Compartment Dimming 3 Circuit Short to Ground
DTC B2740DTC B2740 00 Front Fog Lamp Switch Circuit Malfunction
DTC B3596DTC B3596 00 Hazard Lamps Request Circuit Malfunction
DTC B3650DTC B3650 08 High Beam Request Signal Circuit Performance - Signal Invalid
DTC B3806DTC B3806 00 High Beam and Headlamp Flash Select Circuit Malfunction
DTC B3881 or B3882DTC B3881 02 Tail Lamp Circuit Short to Ground DTC B3881 04 Tail Lamp Circuit Open DTC B3882 02 Right Tail Lamp Circuit Short to Ground DTC B3882 04 Right Tail Lamp Circuit Open
DTC B3883DTC B3883 02 License Plate Lamp Circuit Short to Ground DTC B3883 04 License Plate Lamp Circuit Open
DTC B3884DTC B3884 02 Center High Mounted Brake Lamp Circuit Short to Ground DTC B3884 04 Center High Mounted Brake Lamp Circuit Open
DTC B3948 or B3949DTC B3948 02 Left Front Turn Signal Circuit Short to Ground DTC B3948 04 Left Front Turn Signal Circuit Open DTC B3949 02 Right Front Turn Signal Circuit Short to Ground DTC B3949 04 Right Front Turn Signal Circuit Open
DTC B3950 or B3951DTC B3950 02 Left Rear Turn Signal Circuit Short to Ground DTC B3950 04 Left Rear Turn Signal Circuit Open DTC B3951 02 Right Rear Turn Signal Circuit Short to Ground DTC B3951 04 Right Rear Turn Signal Circuit Open
DTC C0010DTC C0010 5A Reverse Gear Signal Circuit Not Plausible
DTC C0277 or C0890DTC C0277 06 Brake Pedal Position Sensor Circuit Short to Ground or Open DTC C0277 07 Brake Pedal Position Sensor Circuit High Voltage DTC C0277 09 Brake Pedal Position Sensor Circuit Too Fast Transitions DTC C0277 4B Brake Pedal Position Sensor Circuit Calibration Not Learned DTC C0890 03 Control Module Voltage Reference Output 3 Circuit Low Voltage DTC C0890 07 Control Module Voltage Reference Output 3 Circuit High Voltage
DTC C0297DTC C0297 02 Brake Applied Output Circuit Short to Ground

DIAGNOSTIC CODE INDEX

Diagnostic Instructions

  1. Perform the «Diagnostic System Check - Vehicle»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
  3. «Diagnostic Procedure Instructions»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

Diagnostic Fault Information

CircuitShort to GroundOpen/High ResistanceShort to VoltageSignal Performance
Interior Backlighting ControlB096A 0221
1. Hazard Backlighting At Full Intensity And Cannot Be Dimmed 2. Hazard Backlighting Do Not Illuminate

Circuit/System Description

The body control module (BCM) supplies a reference voltage to the headlamp and panel dimmer switch. When the dimmer switch is placed in a desired brightness position, reference voltage is applied through the dimmer switch resistor ladder to the BCM. The BCM interprets this voltage signal, then applies a pulse width modulated (PWM) voltage to the LED dimming supply circuit to all related interior lamps, illuminating them to the desired level of brightness.

Conditions for Running the DTC

The ignition is ON.

Conditions for Setting the DTC

B096A 02

The BCM detects a short to ground on the LED backlight lamp control circuit.

Action Taken When the DTC Sets

The BCM will not dim or illuminate any LED backlighting supplied by the backlight lamp control circuits.

Conditions for Clearing the DTC

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

Reference Information

Schematic Reference

Connector End View Reference

Description and Operation

Electrical Information Reference

  1. «Circuit Testing»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «Testing for Intermittent Conditions and Poor Connections»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
  4. «Wiring Repairs»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

Ignition ON, observe the scan tool Hazard Lamps Switch Backlight Command parameter while operating the dimmer switch from high to low. The reading should change from a high percent to a low percent as the switch is activated.

Circuit/System Testing

  1. Ignition OFF, disconnect the harness connector at the S48C multifunction switch 1-instrument panel.
  2. Test for less than 5 ohms between the ground circuit terminal 7 and ground. If greater than the specified range, test the ground circuit for an open/high resistance.
  3. Connect a test lamp between the backlight control circuit terminal 8 and ground.
  4. Ignition ON, vary the interior lamp dimming switch from dim to full bright. The test lamp should dim and then become full bright. If the test lamp cannot be dimmed, test the control circuit for a short to voltage. If the circuit tests normal, replace the K9 BCM. If the test lamp is always OFF, test the control circuit for open/high resistance or short to ground. If the circuit tests normal, replace the K9 BCM.
  5. If all circuits test normal, replace the S48C multifunction switch 1-instrument panel.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

  1. «Headlamp Switch Replacement»(/buick/regal/v-2009-2013/remont/exterior-lights/#lighting-system)
  2. «Control Module References»(/buick/regal/v-2009-2013/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for BCM replacement, programming and setup
  1. Perform the «Diagnostic System Check - Vehicle»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
  3. «Diagnostic Procedure Instructions»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.
CircuitShort to GroundOpen/High ResistanceShort to VoltageSignal Performance
Headlamp Switch B+B1405 03, B1529 03, B257B 03, 1B257B 03, 1
Instrument Panel Lamps Dimmer Switch SignalB257B 03, 1B257B 03, 1B257B 07
Front Fog Lamp Relay Control222
Front Fog Lamp Control222
Front Fog Lamp Ground2
Headlamp Switch GroundB257B 03
1. Interior Backlighting Malfunction 2. Front Fog Lamps Malfunction

The body control module (BCM) supplies battery positive voltage to the backlight dimmer switch, which is part of the headlamp switch. When the backlight dimmer switch is placed in a desired brightness position, reference voltage is applied to the BCM. The BCM interprets this voltage signal, then applies a pulse width modulated (PWM) voltage to the LED dimming supply circuit to all related interior lamps, illuminating them to the desired level of brightness.

The ignition is ON.

B1405 03, B1529 03, or B257B 03

The BCM detects less than 0.3 V on the dimmer switch signal circuit.

B1405 07, B1529 07, or B257B 07

The BCM detects a voltage greater than 12.2 V on dimmer switch signal circuit.

The BCM will not dim or illuminate any LED backlighting supplied by the backlight lamp control circuits.

  1. The condition responsible for setting the DTC no longer exists.
  2. A history DTC will clear once 100 consecutive fault free ignition cycles have occurred.

Schematic Reference

  1. «Interior Lights Dimming Schematics»(/buick/regal/v-2009-2013/remont/exterior-lights/#lighting-system)
  2. «Steering Wheel Secondary/Configurable Control Schematics»(/buick/regal/v-2009-2013/remont/memory-modules/#secondary-and-configurable-customer-control-system)

Connector End View Reference

Description and Operation

Electrical Information Reference

  1. «Circuit Testing»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «Testing for Intermittent Conditions and Poor Connections»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
  4. «Wiring Repairs»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

Ignition ON, headlamps ON, vary the interior backlight dimming from low to full bright by using the dimmer switch. The interior backlighting should start dim and then become full bright.

  1. Ignition OFF, disconnect the harness connector at the S30 headlamp switch.
  2. Test for less that 10 ohms between the ground circuit terminal 6 and ground. If greater than the specified range, test the ground circuit for an open high/resistance.
  3. Ignition ON, verify that a test lamp illuminates between the B+ circuit terminal 1 and ground. If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the K9 BCM.
  4. Ignition ON, test for less than 0.3 V between signal circuit terminal 12 and ground. If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the K9 BCM.
  5. Install a 3 A fused jumper wire between the signal circuit terminal 12 and the B+ circuit terminal 1. The interior backlighting should be dimmed. If the interior backlighting is not dimmed, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the K9 BCM.
  6. If all circuits test normal, test or replace the S30 headlamp switch.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

  1. «Headlamp Switch Replacement»(/buick/regal/v-2009-2013/remont/exterior-lights/#lighting-system)
  2. «Control Module References»(/buick/regal/v-2009-2013/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for BCM replacement, programming and setup
  1. Perform the «Diagnostic System Check - Vehicle»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
  3. «Diagnostic Procedure Instructions»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.
CircuitShort to GroundOpen/High ResistanceShort to VoltageSignal Performance
Courtesy Lamp Control - Terminal 2 X7B1480 0211
1. Courtesy Lamps Malfunction

The body control module (BCM) supplies battery voltage to the dome/reading lamps - front and left and right sunshade lamps via the courtesy lamp control circuit. When a sunshade mirror is opened, the switch contact close allowing battery voltage to flow illuminating the respective lamps. The front reading lamps are controlled by individual switches that are activated by the operator when additional cabin lighting is required. In the event that any of these courtesy lamps were to remain illuminated for more than 10 minutes with the vehicle ON/OFF switch in the OFF position and no doors opened, the BCM will deactivate the courtesy lamp control circuit to prevent total battery discharge.

Battery voltage must be between 9-16 V.

The BCM detects a short to ground in the courtesy lamp control circuit.

Actions Taken When the DTC Sets

The BCM will disable the circuit and courtesy lamps controlled by the circuit.

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

Schematic Reference

Connector End View Reference

Description and Operation

Electrical Information Reference

  1. «Circuit Testing»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «Testing for Intermittent Conditions and Poor Connections»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
  4. «Wiring Repairs»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

Note. Each courtesy lamp component controlled by the courtesy lamp control circuit terminal 2 X7 may need to be disconnected to isolate a short to voltage or a short to ground. Use the schematic to identify the following: Each component's control and ground circuit terminals Courtesy lamp components the vehicle is equipped with Component locations on the courtesy lamp control circuit

  1. Ignition OFF, disconnect the harness connector at any component with inoperative courtesy lamps controlled by the courtesy lamp control circuit terminal 2 X7.
  2. Connect a test lamp between the appropriate control circuit terminal and ground.
  3. Ignition ON, command the Inadvertent Load ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states. If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the K9 BCM. If the test lamp is always OFF, test the control circuit for a short to ground or open/high resistance. If the circuit tests normal, replace the K9 BCM.
  4. If all circuits test normal, replace the inoperative courtesy lamp.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for BCM replacement, setup and programming

  1. Perform the «Diagnostic System Check - Vehicle»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
  3. «Diagnostic Procedure Instructions»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.
CircuitShort to GroundOpen/High ResistanceShort to VoltageSignal Performance
Fog Lamp Relay ControlB2530 02B2530 04B2530 01

The front fog lamp relay is supplied with battery voltage at all times. The front fog lamp switch signal circuit is grounded momentarily by pressing the front fog lamp switch. The body control module (BCM) energizes the front fog lamp relay by applying ground to the front fog lamp relay control circuit. When the front fog lamp relay is energized, the relay switch contacts close and battery voltage is applied through the front fog lamp fuse to the front fog lamp supply voltage circuit which illuminates the front fog lamps.

Ignition ON.

B2530 01

The BCM detects a short to voltage on the fog lamp relay control circuit.

B2530 02

The BCM detects a short to ground on the fog lamp relay control circuit.

B2530 04

The BCM detects an open circuit on the fog lamp relay control circuit.

  1. The DTC will be current for as long as the fault is present.
  2. When the fault is no longer present, the DTC will be a history DTC.
  3. A history DTC will clear after 50 ignition cycles.

Schematic Reference

Connector End View Reference

Description and Operation

Electrical Information Reference

  1. «Circuit Testing»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «Testing for Intermittent Conditions and Poor Connections»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
  4. «Wiring Repairs»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

Ignition ON, command the Fog Lamps ON and OFF with a scan tool. The fog lamps should turn ON and OFF when changing between the commanded states.

  1. Ignition OFF, disconnect the X2 harness connector at the X50A underhood fuse block.
  2. Ignition ON, verify that a test lamp does not illuminate between the control circuit terminal 19 and ground. If the test lamp is ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the K9 BCM.
  3. Connect a test lamp between the control circuit terminal 19 and B+.
  4. Command the Fog Lamps ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states. If the test lamp is always OFF, test the control circuit for an open/high resistance. If the circuit tests normal, replace the K9 BCM. If the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the K9 BCM.
  5. If all circuits test normal, replace the X50A underhood fuse block.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

  1. «Fuse Block Replacement»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-repair-instructions)
  2. «Control Module References»(/buick/regal/v-2009-2013/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for BCM replacement, programming and setup
  1. Perform the «Diagnostic System Check - Vehicle»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
  3. «Diagnostic Procedure Instructions»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.
CircuitShort to GroundOpen/High ResistanceShort to VoltageSignal Performance
Backup Lamps ControlB2545 02B2545 041
Backup Lamps Ground2
1. Backup Lamps Always ON 2. Backup Lamps Inoperative

When the engine is running and the transmission is placed in reverse gear, the transmission control module (TCM) sends a serial data message to the body control module (BCM). The message indicates that the gear selector is in the reverse position. The BCM applies battery voltage to the backup lamps. The backup lamps are permanently grounded. Once the driver moves the gear selector out of the reverse position, a message is sent by the TCM via serial data requesting the BCM to remove battery voltage from the backup lamp signal circuit. The BCM will not apply battery voltage to the backup lamps if the engine is not running.

Reverse Gear engaged.

B2545 02

The BCM detects a short to ground on the backup lamps control circuit.

B2545 04

The BCM detects an open circuit on the backup lamps control circuit.

The appropriate backup lamp is inoperative.

The condition for setting the DTC is no longer present.

Schematic Reference

Connector End View Reference

Description and Operation

Electrical Information Reference

  1. «Circuit Testing»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «Testing for Intermittent Conditions and Poor Connections»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
  4. «Wiring Repairs»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

Ignition ON, command the Backup Lamps ON and OFF with a scan tool. The backup lamps should turn ON and OFF when changing between the commanded states.

Note. If DTC B2545 or B3950 are set fuse block underhood BCM fuse 32 may be open. Test circuit and fuse before replacing BCM.

  1. Ignition OFF, disconnect the harness connector at the appropriate E42 tail lamp assembly.
  2. Test for less than 30 ohms between the ground circuit terminal F and ground. If greater than the specified value, test the ground circuit for an open/high resistance.
  3. Connect a test lamp between the control circuit terminal D and ground.
  4. Command the Backup Lamps ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states. If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the K9 BCM. If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuits test normal, replace the K9 BCM.
  5. If all circuits test normal, replace the E42 tail lamp assembly.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

  1. «Tail Lamp Replacement»(/buick/regal/v-2009-2013/remont/exterior-lights/#lighting-system)
  2. «Tail Lamp Bulb Replacement»(/buick/regal/v-2009-2013/remont/exterior-lights/#lighting-system)
  3. «Control Module References»(/buick/regal/v-2009-2013/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for BCM replacement, programming and setup
  1. Perform the «Diagnostic System Check - Vehicle»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
  3. «Diagnostic Procedure Instructions»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.
CircuitShort to GroundOpen/High ResistanceShort to VoltageSignal Performance
Interior Backlighting ControlB255D 0221
Interior Backlighting Ground2
1. Accent Lamp LEDs at Full Intensity and Cannot be Dimmed or Turned OFF 2. Accent Lamp LEDs do Not Illuminate

The body control module (BCM) supplies a voltage reference to the dimmer switch, which is part of the headlamp switch. When the dimmer switch is placed in a desired brightness position, reference voltage is applied through the dimmer switch to the BCM. The BCM interprets this voltage signal, then applies a variable voltage through the LED backlight lamp control circuit.

  1. The ignition is ON.
  2. The headlamps or park lamps are ON.

The BCM detects a short to ground on the LED backlight lamp control circuit.

The BCM will not dim or illuminate any LED backlighting supplied by the backlight lamp control circuits.

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

Schematic Reference

  1. «Interior Lights Schematics»(/buick/regal/v-2009-2013/remont/exterior-lights/#lighting-system)
  2. «Interior Lights Dimming Schematics»(/buick/regal/v-2009-2013/remont/exterior-lights/#lighting-system)

Connector End View Reference

Description and Operation

Electrical Information Reference

  1. «Circuit Testing»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «Testing for Intermittent Conditions and Poor Connections»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
  4. «Wiring Repairs»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

Ignition ON, command the Interior Accent Lighting 2 ON and OFF with a scan tool. The interior accent lighting should turn ON and OFF when changing between the commanded states.

Note. Each back lighted component may need to be disconnected to isolate a short to voltage or short to ground. Use the schematic to identify the following: Back lighted components the vehicle is equipped with. Component locations on the back lighting dimming control circuit. Each components control and ground circuit terminals.

  1. Ignition OFF, disconnect the harness connector at any component with inoperative backlighting.
  2. Ignition OFF, scan tool disconnected, interior lamps OFF, doors CLOSED, test for less than 5 ohms between the ground circuit and ground. If greater than the specified value, test the ground circuit for an open/high resistance.
  3. Connect a test lamp between the control circuit and ground.
  4. Command the Interior Accent Lighting 2 ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states. If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the K9 BCM. If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the K9 BCM.
  5. If all circuits test normal, test or replace the component with the inoperative backlighting.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

  1. Refer to the appropriate replacement procedure for the component causing the condition.
  2. «Control Module References»(/buick/regal/v-2009-2013/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for BCM replacement, programming and setup
  1. Perform the «Diagnostic System Check - Vehicle»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
  3. «Diagnostic Procedure Instructions»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.
CircuitShort to GroundOpen/High ResistanceShort to VoltageSignal Performance
Rear Compartment Courtesy Lamp ControlB2560 0221
1. Rear Compartment Courtesy Lamp Will Always Be ON 2. Rear Compartment Courtesy Lamp Will Always Be OFF

When the body control module (BCM) receives a trunk open signal, the BCM supplies B+ to the rear compartment courtesy lamp control circuit. This will illuminate the rear compartment courtesy lamp.

The trunk is in open position.

The BCM detects a short to ground on the rear compartment courtesy lamp control circuit.

The rear compartment courtesy lamp is OFF.

The condition responsible for setting the DTC no longer exists.

Schematic Reference

Connector End View Reference

Description and Operation

Electrical Information Reference

  1. «Circuit Testing»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «Testing for Intermittent Conditions and Poor Connections»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
  4. «Wiring Repairs»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

Command the Cargo Lamp ON and OFF with a scan tool. The cargo lamp should turn ON and OFF when changing between the commanded states.

  1. Ignition OFF, disconnect the harness connector at the E8S rear compartment courtesy lamp.
  2. Test for less than 5 ohms between the ground circuit terminal 2 and ground. If greater than the specified range, test the ground circuit for an open/high resistance.
  3. Connect a test lamp between the control circuit terminal 1 and ground.
  4. Ignition ON, command the Cargo Lamp ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states. If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the K9 BCM. If the test lamp is always OFF, test the control circuit for a short to ground or open/high resistance. If the circuit tests normal, replace the K9 BCM.
  5. If the all circuits test normal, replace the E8S rear compartment courtesy lamp.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

  1. «Rear Compartment Courtesy Lamp Replacement»(/buick/regal/v-2009-2013/remont/exterior-lights/#lighting-system)
  2. «Control Module References»(/buick/regal/v-2009-2013/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for BCM replacement, programming and setup
  1. Perform the «Diagnostic System Check - Vehicle»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
  3. «Diagnostic Procedure Instructions»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.
CircuitShort to GroundOpen/High ResistanceShort to VoltageSignal Performance
Rear Compartment Courtesy Lamp Control2B256A 041
Rear Compartment Courtesy Lamp Ground2
1. Rear Compartment Courtesy Lamp Always ON 2. Rear Compartment Courtesy Lamp Always OFF

When the body control module (BCM) receives a liftgate open signal, the BCM supplies B+ to the rear compartment courtesy lamp control circuit. This will illuminate the rear compartment courtesy lamp.

  1. Ignition ON.
  2. The system voltage is between 9-16 V.

The BCM detects an open circuit on the rear compartment courtesy lamp control circuit.

The rear compartment courtesy lamp is inoperative.

A current DTC clears when the diagnostic runs and passes.

Schematic Reference

Connector End View Reference

Description and Operation

Electrical Information Reference

  1. «Circuit Testing»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «Testing for Intermittent Conditions and Poor Connections»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
  4. «Wiring Repairs»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

Ignition ON, command the Cargo Lamp ON and OFF with a scan tool. The rear compartment courtesy lamp should turn ON and OFF when changing between the commanded states.

  1. Ignition OFF, disconnect the harness connector at the E8S rear compartment courtesy lamp.
  2. Test for less than 5 ohms between the ground circuit terminal 2 and ground. If greater than the specified range, test the ground circuit for an open/high resistance.
  3. Connect a test lamp between the control circuit terminal 1 and ground.
  4. Command the Cargo Lamp ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states. If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the K9 BCM. If the test lamp is always OFF, test the control circuit for a short to round or open/high resistance. If the circuit tests normal, replace the K9 BCM.
  5. If the all circuits test normal, replace the E8S rear compartment courtesy lamp.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

  1. «Rear Compartment Courtesy Lamp Replacement»(/buick/regal/v-2009-2013/remont/exterior-lights/#lighting-system)
  2. «Control Module References»(/buick/regal/v-2009-2013/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for BCM replacement, programming and setup
  1. Perform the «Diagnostic System Check - Vehicle»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
  3. «Diagnostic Procedure Instructions»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.
CircuitShort to GroundOpen/High ResistanceShort to VoltageSignal Performance
Trunk Lamp ControlB2570 02B2570 04B2570 01
Ground1
1. Rear Compartment Lamps Inoperative

When the body control module (BCM) receives a trunk open signal, the BCM supplies B+ to the trunk lamp control circuit. This will illuminate the rear compartment courtesy lamp.

The trunk is in open position.

B2570 01

The BCM detects a short to battery on the trunk lamp control circuit.

B2570 02

The BCM detects a short to ground on the trunk lamp control circuit.

B2570 04

The BCM detects an open circuit on the trunk lamp control circuit.

The rear compartment courtesy lamp will not operate.

The condition responsible for setting the DTC no longer exists.

Schematic Reference

Connector End View Reference

Description and Operation

Electrical Information Reference

  1. «Circuit Testing»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «Testing for Intermittent Conditions and Poor Connections»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
  4. «Wiring Repairs»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

Command the Trunk Lamp ON and OFF with a scan tool. The rear compartment lamp should turn ON and OFF when changing between the commanded states.

  1. Ignition OFF, disconnect the harness connector at the E8S rear compartment courtesy lamp.
  2. Test for less than 5 ohms between the ground circuit terminal 2 and ground. If greater than the specified range, test the ground circuit for an open/high resistance.
  3. Connect a test lamp between the control circuit terminal 1 and ground.
  4. Command the Trunk Lamp ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states. If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the K9 BCM. If the test lamp is always OFF, test the control circuit for a short to round or open/high resistance. If the circuit tests normal, replace the K9 BCM.
  5. If the all circuits test normal, replace the E8S rear compartment courtesy lamp.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

  1. «Rear Compartment Courtesy Lamp Replacement»(/buick/regal/v-2009-2013/remont/exterior-lights/#lighting-system)
  2. «Control Module References»(/buick/regal/v-2009-2013/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for BCM replacement, programming and setup
  1. Perform the «Diagnostic System Check - Vehicle»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
  3. «Diagnostic Procedure Instructions»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.
CircuitShort to GroundOpen/High ResistanceShort to VoltageSignal Performance
BCM B+ Terminal 3 X1B2575 04B2575 04
BCM B+ Terminal 2 X1B2699 02B2699 02
Left Headlamp ControlB2575 02B2575 041
Right Headlamp ControlB2699 02B2699 041
Left Headlamp GroundB2575 04
Right Headlamp GroundB2699 04
1. Low Beam Headlamps Always ON

With the headlamp switch in the ON position, the headlamp ON signal circuit is grounded through the headlamp switch. The body control module (BCM) responds by applying current to the left and right low beam headlamp control circuits illuminating the low beam headlamps.

  1. Battery voltage must be between 9-16 V.
  2. Low beam headlamps ON.

B2575 02

The BCM detects a short to ground in the left headlamp low beam control circuit.

B2575 04

The BCM detects an open in the left headlamp low beam control circuit or its B+ circuit or an open/high resistance in the left headlamp low beam ground circuit.

B2699 02

The BCM detects a short to ground in the right headlamp low beam control circuit.

B2699 04

The BCM detects an open in the right headlamp low beam control circuit or its B+ circuit or an open/high resistance on the right headlamp low beam ground circuit.

When DTC B2575 or B2699 is present, the associated low beam headlamp will not operate.

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

Schematic Reference

Connector End View Reference

Description and Operation

Electrical Information Reference

  1. «Circuit Testing»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «Testing for Intermittent Conditions and Poor Connections»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
  4. «Wiring Repairs»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

  1. Ignition OFF, disconnect the harness X1 harness connector at the K9 BCM.
  2. Ignition ON, verify that a test lamp illuminates between the B+ circuit terminal listed below and ground: B+ circuit terminal 2 B+ circuit terminal 3 If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.
  3. Ignition OFF, connect the harness X1 harness connector at the K9 BCM.
  4. Disconnect the harness connector at the appropriate E4 headlamp-low beam.
  5. Test for less than 30 ohms between the ground circuit terminal 1 and ground. If greater than the specified range, test the ground circuit for an open/high resistance.
  6. Connect a test lamp between the control circuit terminal 3 and ground.
  7. Ignition ON, command the low beam lamps ON and OFF with a scan tool. The test lamp should turn ON and OFF while changing between the commanded states. If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the K9 BCM. If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the K9 BCM
  8. If all circuits test normal, replace the headlamp bulb.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

  1. «Headlamp Replacement»(/buick/regal/v-2009-2013/remont/exterior-lights/#lighting-system)
  2. «Headlamp Bulb Replacement (TT4 Low Beam)»(/buick/regal/v-2009-2013/remont/exterior-lights/#lighting-system) , «Headlamp Bulb Replacement (TT4 High Beam)»(/buick/regal/v-2009-2013/remont/exterior-lights/#lighting-system)
  3. «Control Module References»(/buick/regal/v-2009-2013/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for BCM replacement, programming and setup
  1. Perform the «Diagnostic System Check - Vehicle»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
  3. «Diagnostic Procedure Instructions»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.
CircuitShort to GroundOpen/High ResistanceShort to VoltageSignal Performance
Headlamp Switch Park Lamp Signal2B257A 002
Headlamp Switch On SignalB257A 0011
Headlamp Switch Headlamps Off SignalB257A 0011
Headlamp Switch Ground1
1. Headlight Auto Function Only 2. Headlight Auto Function Disabled

The body control module (BCM) monitors the 12 V signal circuits for the headlamps off, headlamps on and park lamp on signal circuits. When the headlamp switch is selected to the desired headlamp function, the signal circuit is pulled to ground and the BCM will detect the voltage drop in that signal circuit and will command the appropriate lights to turn ON or turn OFF.

The ignition is in the ON, ACCESSORY or RUN position.

The BCM receives an unexpected signal along either the headlamp switch OFF signal circuit, the headlamp ON signal circuit or the park lamp ON signal circuit.

The automatic headlamps will malfunction.

  1. The DTC will be current for as long as the fault is present.
  2. When the fault is no longer present, the DTC will be a history DTC.
  3. A history DTC will clear after 50 ignition cycles.

Schematic Reference

Connector End View Reference

Description and Operation

Electrical Information Reference

  1. «Circuit Testing»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «Testing for Intermittent Conditions and Poor Connections»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
  4. «Wiring Repairs»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

Ignition ON, observe the scan tool Headlamps On Switch, Park Lamps Switch and Automatic Headlamps Disable Switch parameters while selecting the headlamp control switch between the Off, park lamps ON and headlamps ON settings. Each parameter should be Inactive and change to Active as each setting is selected.

  1. Ignition OFF, disconnect the harness connector at the S30 headlamp switch.
  2. Ignition OFF, test for less than 30 ohms between the ground circuit terminal 6 and ground. If greater than the specified range, test the ground circuit for an open/high resistance.
  3. Ignition ON, verify the scan tool Park Lamps Switch parameter is Inactive. If not the specified value, test the signal circuit terminal 3 for a short to ground. If the circuit tests normal, replace the K9 BCM.
  4. Install a 3 A fused jumper wire between the signal circuit terminal 3 and the ground circuit terminal 6. Verify the scan tool Park Lamps Switch is Active. If not the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the K9 BCM.
  5. Verify the scan tool Headlamps On Switch parameter is Inactive. If not the specified value, test the signal circuit terminal 4 for a short to ground. If the circuit tests normal, replace the K9 BCM.
  6. Install a 3 A fused jumper wire between the signal circuit terminal 4 and the ground circuit terminal 6. Verify the scan tool Headlamps On Switch is Active. If not the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the K9 BCM.
  7. Verify the scan tool Automatic Headlamps Disable Switch parameter is Inactive. If not the specified value, test the signal circuit terminal 5 for a short to ground. If the circuit tests normal, replace the K9 BCM.
  8. Install a 3 A fused jumper wire between the signal circuit terminal 5 and the ground circuit terminal 6. Verify the scan tool Automatic Headlamps Disable Switch is Active. If not the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the K9 BCM.
  9. If all circuits test normal, test or replace the S30 headlamp switch.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

  1. «Headlamp Switch Replacement»(/buick/regal/v-2009-2013/remont/exterior-lights/#lighting-system)
  2. «Control Module References»(/buick/regal/v-2009-2013/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for BCM replacement, programming and setup
  1. Perform the «Diagnostic System Check - Vehicle»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
  3. «Diagnostic Procedure Instructions»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.
CircuitShort to GroundOpen/High ResistanceShort to VoltageSignal Performance
High Beam ControlB2580 0211
1. High Beam Lamps Inoperative

The headlamp high beam relay is supplied with battery voltage at all times. The turn signal/multifunction switch signal circuit is grounded by pressing the turn signal/multifunction switch. The body control module (BCM) energizes the headlamp high beam relay by applying ground to the headlamp high beam relay control circuit. When the headlamp high beam relay is energized, the relay switch contacts close and battery voltage is applied through the high beam lamp fuses to the high beam lamp supply voltage circuit which illuminates the high beam lamps.

High beam lamps ON.

The BCM detects a short to ground on the high beam control circuit.

The high beam lamps are always ON.

The condition for setting the DTC is no longer present.

Schematic Reference

Connector End View Reference

Description and Operation

Electrical Information Reference

  1. «Circuit Testing»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «Testing for Intermittent Conditions and Poor Connections»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
  4. «Wiring Repairs»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

Ignition ON, headlamps ON, turn the high beam headlamps ON and OFF by applying and releasing the turn signal/multifunction switch. The high beam headlamps should turn ON and OFF when changing between the selected states.

  1. Ignition OFF, disconnect the KR48 headlamp high beam relay.
  2. Ignition ON, verify that a test lamp does not illuminate between the control circuit terminal 30 and ground. If the test lamp illuminates, test the control circuit for a short to voltage.
  3. Verify that a test lamp illuminates between the B+ circuit terminal 85 and ground. If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.
  4. Verify that a test lamp illuminates between the B+ circuit terminal 87 and ground. If the test lamp does not illuminate, test the B+ circuit for an open/high resistance.
  5. Disconnect the harness connector at the appropriate E13 headlamp.
  6. Test for less than 5 ohms between the ground circuit terminal 1 and ground. If greater than the specified range, test the ground circuit for an open/high resistance.
  7. Connect the harness connector at the E13 headlamp.
  8. Connect a 10 A fused jumper wire between the B+ circuit terminal 87 and the control circuit terminal 30. Verify the high beam headlamp is activated. If the high beam headlamp does not activate and the circuit fuse is good, test the control circuit for an open/high resistance. If the circuit tests normal, test or replace the E13 headlamp. If the high beam headlamp does not activate and the circuit fuse is open, test the control circuit for a short to ground. If the circuit tests normal, test or replace the E13 headlamp.
  9. Connect a test lamp between the B+ circuit terminal 85 and the control circuit terminal 86.
  10. Turn the high beam headlamps ON and OFF using the S78 turn signal/multifunction switch. The test lamp should turn ON and OFF when changing between the selected states. If the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the K9 BCM. If the test lamp is always OFF, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the K9 BCM.
  11. If all circuits test normal, test or replace the KR48 headlamp high beam relay.

Perform the Diagnostic Repair Verification after completing the repair.

  1. «Headlamp Replacement»(/buick/regal/v-2009-2013/remont/exterior-lights/#lighting-system)
  2. «Headlamp Bulb Replacement (TT4 Low Beam)»(/buick/regal/v-2009-2013/remont/exterior-lights/#lighting-system) , «Headlamp Bulb Replacement (TT4 High Beam)»(/buick/regal/v-2009-2013/remont/exterior-lights/#lighting-system)
  3. «Relay Replacement (Within an Electrical Center)»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-repair-instructions) , «Relay Replacement (Attached to Wire Harness)»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-repair-instructions)
  4. «Control Module References»(/buick/regal/v-2009-2013/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for BCM, replacement, programming and setup
  1. Perform the «Diagnostic System Check - Vehicle»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
  3. «Diagnostic Procedure Instructions»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.
CircuitShort to GroundOpen/High ResistanceShort to VoltageSignal Performance
Left Park Lamps ControlB2585 02B2585 04B2585 01
Right Park Lamps ControlB3867 02B3867 04B3867 01
Left Park Lamps Ground1
Right Park Lamps Ground1
1. Park Lamp Inoperative

The body control module (BCM) energizes the park lamps by applying voltage to the park lamp control circuit. When the park lamp control circuit is energized, the park lamps are illuminated.

B2585 01

Headlamp switch in OFF position.

B2585 02 or B2585 04

Park lamps are switched ON.

B3867 01, B3867 02 or B3867 04

Park lamps are switched ON.

B3867 02

Headlamp switch in park or low beam position.

B2585 01 or B3867 01

The BCM detects a short to voltage on the appropriate park lamp control circuit.

B2585 02 or B3867 02

The BCM detects a short to ground on the appropriate park lamp control circuit.

B2585 04 or B3867 04

The BCM detects an open circuit on the appropriate park lamp control circuit.

No action taken by the BCM.

The condition for setting the DTC is no longer present.

Schematic Reference

Connector End View Reference

Description and Operation

Electrical Information Reference

  1. «Circuit Testing»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «Testing for Intermittent Conditions and Poor Connections»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
  4. «Wiring Repairs»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

Ignition ON, turn the park lamps ON and OFF by turning the headlamp switch between the OFF and PARK positions. The park lamps should turn ON and OFF when changing between the selected states.

  1. Ignition OFF, disconnect the harness connector at the appropriate park lamp.
  2. Test for less than 5 ohms between the ground circuit terminal listed below and ground: E13 Headlamp - terminal 1 E42 Tail Lamp Assembly - terminal F E7 License Lamp - terminal 2 If greater than the specified value, test the ground circuit for an open/high resistance.
  3. Connect a test lamp between the control circuit terminal listed below and ground: E13 Headlamp - park lamp - terminal 4 E13 Headlamp - side marker lamp - terminal 7 E42 Tail Lamp Assembly - terminal A E7 License Lamp - terminal 1
  4. Command the appropriate Park Lamp ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states. If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the K9 BCM. If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuits test normal, replace the K9 BCM.
  5. If all the circuits test normal, replace the park lamp.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

  1. «Headlamp Replacement»(/buick/regal/v-2009-2013/remont/exterior-lights/#lighting-system)
  2. «Headlamp Bulb Replacement (TT4 Low Beam)»(/buick/regal/v-2009-2013/remont/exterior-lights/#lighting-system) , «Headlamp Bulb Replacement (TT4 High Beam)»(/buick/regal/v-2009-2013/remont/exterior-lights/#lighting-system)
  3. «Tail Lamp Replacement»(/buick/regal/v-2009-2013/remont/exterior-lights/#lighting-system)
  4. «Tail Lamp Bulb Replacement»(/buick/regal/v-2009-2013/remont/exterior-lights/#lighting-system)
  5. «Rear License Plate Lamp Replacement»(/buick/regal/v-2009-2013/remont/exterior-lights/#lighting-system)
  6. «Rear License Plate Lamp Bulb Replacement»(/buick/regal/v-2009-2013/remont/exterior-lights/#lighting-system)
  7. «Control Module References»(/buick/regal/v-2009-2013/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for BCM replacement, programming and setup
  1. Perform the «Diagnostic System Check - Vehicle»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
  3. «Diagnostic Procedure Instructions»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.
CircuitShort to GroundOpen/High ResistanceShort to VoltageSignal Performance
Headlamp Low Beam Relay ControlB258A 02B258A 04B258A 01

When the headlamp switch is placed in low beam position, the body control module (BCM) supplies battery voltage to the respective headlamp control circuits.

The headlamp switch is in the low beam position.

B258A 01

The BCM detects a short to voltage in the headlamp low beam control circuit.

B258A 02

The BCM detects a short to ground in the headlamp low beam control circuit.

B258A 04

The BCM detects an open/high resistance in the headlamp low beam control circuit.

B258A 01 or B258A 04

The low beam headlamps will be inoperative.

B258A 02

The low beam headlamps will be continuously illuminated.

  1. The DTC will be current for as long as the fault is present.
  2. When the fault is no longer present, the DTC will be a history DTC.
  3. A history DTC will clear after 50 ignition cycles.

Schematic Reference

Connector End View Reference

Description and Operation

Electrical Information Reference

  1. «Circuit Testing»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «Testing for Intermittent Conditions and Poor Connections»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
  4. «Wiring Repairs»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

Ignition ON, command the Headlamp Low Beam ON and OFF with a scan tool. The low beam headlamps should turn ON and OFF when changing between the commanded states.

  1. Ignition OFF, disconnect the harness connector at the appropriate E13 headlamp.
  2. Test for less than 5 ohms between the ground circuit terminal 1 and ground. If greater than the specified range, test the ground circuit for an open/high resistance.
  3. Connect a test lamp between the control circuit terminal 3 and the ground circuit terminal 1.
  4. Command Headlamp Low Beam ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states. If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the K9 BCM. If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the K9 BCM.
  5. If all circuits test normal, test or replace the E13 headlamp.

Component Testing

Relay Test

  1. Ignition OFF, disconnect the KR49 headlamp low beam relay.
  2. Test for 60-180 ohms between terminals 85 and 86. If not within the specified range, replace the KR49 headlamp low beam relay.
  3. Test for infinite resistance between the following terminals: 30 and 86 30 and 87 30 and 85 85 and 87 If not the specified value, replace the KR49 headlamp low beam relay.
  4. Install a 15 A fused jumper wire between relay terminal 85 and 12 V. Install a jumper wire between relay terminal 86 and ground. Test for less than 2 ohms between terminals 30 and 87. If greater than the specified range, replace the KR49 headlamp low beam relay.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

  1. «Headlamp Replacement»(/buick/regal/v-2009-2013/remont/exterior-lights/#lighting-system)
  2. «Headlamp Bulb Replacement (TT4 Low Beam)»(/buick/regal/v-2009-2013/remont/exterior-lights/#lighting-system) , «Headlamp Bulb Replacement (TT4 High Beam)»(/buick/regal/v-2009-2013/remont/exterior-lights/#lighting-system)
  3. «Control Module References»(/buick/regal/v-2009-2013/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for BCM replacement, programming and setup
  1. Perform the «Diagnostic System Check - Vehicle»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
  3. «Diagnostic Procedure Instructions»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.
CircuitShort to GroundOpen/High ResistanceShort to VoltageSignal Performance
Headlamp and Panel Dimmer Switch B+B257B 03, B1405 03, B1529 03B257B 03
Headlamp and Panel Dimmer Switch SignalB257B 03B257B 03B257B 07
LED Interior Backlighting ControlB2610 0221
Interior Backlighting Ground2
1. Interior backlighting at full intensity and cannot be dimmed 2. Interior backlighting does not illuminate

The body control module (BCM) supplies a reference voltage to the dimmer switch, which is part of the headlamp switch. When the dimmer switch is placed in a desired brightness position, reference voltage is applied through the dimmer switch to the BCM. The BCM interprets this voltage signal, then applies a pulse width modulated (PWM) voltage to the LED dimming supply circuit to all related interior lamps, illuminating them to the desired level of brightness.

  1. The ignition is ON.
  2. The headlamps or park lamps are ON.

The BCM detects a short to ground on the LED backlight lamp control circuit.

The BCM will not dim or illuminate any LED backlighting supplied by the backlight lamp control circuits.

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

Schematic Reference

Connector End View Reference

Description and Operation

Electrical Information Reference

  1. «Circuit Testing»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «Testing for Intermittent Conditions and Poor Connections»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
  4. «Wiring Repairs»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

Observe the scan tool LED Backlight Dimming Command parameter while operating the dimmer switch from high to low. The parameter should change from a high percent to a low percent as the switch is activated.

  1. Ignition OFF, disconnect the harness connector at any component with inoperative backlighting.
  2. Ignition OFF, scan tool disconnected, interior lamps OFF, doors CLOSED, test for less than 5 ohms between the ground circuit and ground. If greater than the specified value, test the ground circuit for an open/high resistance.
  3. Connect a test lamp between the control circuit and ground.
  4. Command the LED Dimming ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states. If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the K9 BCM. If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the K9 BCM.
  5. If all circuits test normal, test or replace the component with inoperative backlighting.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

  1. Refer to the appropriate replacement procedure for the component causing the condition.
  2. «Control Module References»(/buick/regal/v-2009-2013/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for BCM replacement, programming and setup
  1. Perform the «Diagnostic System Check - Vehicle»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
  3. «Diagnostic Procedure Instructions»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.
CircuitShort to GroundOpen/High ResistanceShort to VoltageSignal Performance
Courtesy Lamps ControlB2615 02B2615 04, 21
Courtesy Lamps Ground2
1. Courtesy Lamps Always Illuminated 2. Courtesy Lamps Do Not Illuminate

Battery voltage for the courtesy lamps is supplied at all times to the body control module (BCM). When the BCM receives a signal to command the courtesy lamps ON, it then applies voltage through the courtesy lamps control circuits to the courtesy lamps.

The BCM attempts to illuminate the courtesy lamps.

B2615 02

The BCM detects a short to ground on the courtesy lamp control circuit.

B2615 04

The BCM detects an open on the courtesy lamp control circuit.

The BCM will not attempt to activate courtesy lamps.

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

Schematic Reference

Connector End View Reference

Description and Operation

Electrical Information Reference

  1. «Circuit Testing»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «Testing for Intermittent Conditions and Poor Connections»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
  4. «Wiring Repairs»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

Command the 1st Row Interior/Courtesy Lamps ON and OFF with a scan tool. The courtesy lamps should turn ON and OFF when changing between commanded states.

  1. Ignition OFF, disconnect the harness connector at any component with inoperative courtesy lamp.
  2. Ignition OFF, scan tool disconnected, interior lamps OFF, doors CLOSED, test for less than 5 ohms between the ground circuit and ground. If greater than the specified value, test the ground circuit for an open/high resistance.
  3. Connect a test lamp between the control circuit and ground.
  4. Command the 1st Row Interior/Courtesy Lamps ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states. If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the K9 BCM. If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the K9 BCM.
  5. If all circuits test normal, test or replace the component with inoperative courtesy lamp.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

  1. Refer to the appropriate replacement procedure for the component causing the condition.
  2. «Control Module References»(/buick/regal/v-2009-2013/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for BCM replacement, setup and programming
  1. Perform the «Diagnostic System Check - Vehicle»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
  3. «Diagnostic Procedure Instructions»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.
CircuitShort to GroundOpen/High ResistanceShort to VoltageSignal Performance
Interior Backlighting ControlB2625 0221
1. Backlighting At Full Intensity And Cannot Be Dimmed Or Turned Off 2. Backlighting Does Not Illuminate

The body control module (BCM) supplies a reference voltage to the dimmer switch, which is part of the headlamp switch. When the dimmer switch is placed in a desired brightness position, reference voltage is applied through the dimmer switch to the BCM. The BCM interprets this voltage signal, then applies a pulse width modulated (PWM) voltage to the backlight lamp control circuit, and the LED dimming control circuit illuminating the backlighting LEDs.

The ignition is ON.

The BCM detects a short to ground on the LED dimming control circuit.

The BCM will not attempt to illuminate the LED indicator lamps when a short circuit to ground is detected.

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

Schematic Reference

Connector End View Reference

Description and Operation

Electrical Information Reference

  1. «Circuit Testing»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «Testing for Intermittent Conditions and Poor Connections»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
  4. «Wiring Repairs»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool Reference

Control Module References for the scan tool information

Observe the LED backlighting components while operating the dimmer switch from high to low. The dimming components should change from a high intensity to low intensity as the switch is activated.

  1. Ignition OFF, disconnect the harness connector at any component with inoperative backlighting.
  2. Ignition OFF, scan tool disconnected, interior lamps OFF, doors CLOSED, test for less than 5 ohms between the ground circuit and ground. If greater than the specified value, test the ground circuit for an open/high resistance.
  3. Connect a test lamp between the control circuit and ground.
  4. Command the LED Dimming ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states. If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the K9 BCM. If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the K9 BCM.
  5. If all circuits test normal, test or replace the component with inoperative backlighting.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

  1. Refer to the appropriate replacement procedure for the component causing the condition.
  2. «Control Module References»(/buick/regal/v-2009-2013/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for BCM replacement, programming and setup
  1. Perform the «Diagnostic System Check - Vehicle»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
  3. «Diagnostic Procedure Instructions»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.
CircuitShort to GroundOpen/High ResistanceShort to VoltageSignal Performance
Turn Signal Repeater Lamp ControlB263A 0221
Turn Signal Repeater Lamp Ground2
1. Turn Signal Repeater Lamp Always ON 2. Turn Signal Repeater Lamp Inoperative

When the keyless entry control module receives a request from the keyless entry transmitter to unlock the doors, the keyless entry control module will send a serial data message to the BCM, the BCM will then command the left and right turn signal repeater lamps to illuminate.

When the BCM will commands the left and right turn signal repeater lamps to illuminate.

B263A 02

The BCM detects a short to ground on the turn signal repeater lamp control circuit.

B263A 04

The BCM detects an open/high resistance on the turn signal repeater lamp control circuit.

The turn signal repeater lamps will be inoperative.

  1. The DTC will be current for as long as the fault is present.
  2. When the fault is no longer present, the DTC will be a history DTC.
  3. A history DTC will clear after 50 ignition cycles.

Schematic Reference

Connector End View Reference

Description and Operation

Electrical Information Reference

  1. «Circuit Testing»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «Testing for Intermittent Conditions and Poor Connections»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
  4. «Wiring Repairs»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

Ignition ON, command the Outside Rear View Mirror Courtesy Lamp ON and OFF with a scan tool. The left and right turn signal repeater lamps should turn ON and OFF when changing between the commanded states.

  1. Ignition OFF, disconnect the harness connector at the appropriate E4 turn signal repeater lamp.
  2. Test for less than 30 ohms between the ground circuit terminal 2 and ground. If greater than the specified value, test the ground circuit for an open/high resistance.
  3. Connect a test lamp between the control circuit terminal 1 and ground.
  4. Command the Outside Rear View Mirror Courtesy Lamp ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states. If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the K9 BCM. If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the K9 BCM.
  5. If all circuits test normal, test or replace the E4 turn signal repeater lamp.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

  1. «Front Side Door Courtesy Lamp Lens Replacement»(/buick/regal/v-2009-2013/remont/exterior-lights/#lighting-system)
  2. «Control Module References»(/buick/regal/v-2009-2013/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for BCM replacement, programming and setup
  1. Perform the «Diagnostic System Check - Vehicle»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
  3. «Diagnostic Procedure Instructions»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.
CircuitShort to GroundOpen/High ResistanceShort to VoltageSignal Performance
Ambient Light Sensor Signal CircuitB2645 03B2645 07B2645 07
Ambient Light Sensor GroundB2645 07

The ambient light sensor is used to monitor outside lighting conditions. The ambient light sensor provides a voltage signal that will vary between 1.4-4.5 V depending on outside lighting conditions. When the headlamp switch is in the AUTO position, the body control module (BCM) monitors the ambient light sensor signal circuit to determine if outside lighting conditions are correct for either daytime running lights or automatic lamp control. In daylight conditions, the BCM will command the daytime running lights ON. During low light conditions, the BCM will command the low beam headlamps ON.

Ignition ON

B2645 03

The BCM detects a voltage below threshold on the ambient light sensor signal circuit.

B2645 07

The BCM detects a voltage above threshold on the ambient light sensor signal circuit.

The condition for setting the DTC is no longer present.

The condition for setting the DTC is no longer present.

Schematic Reference

Connector End View Reference

Description and Operation

Electrical Information Reference

  1. «Circuit Testing»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «Testing for Intermittent Conditions and Poor Connections»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
  4. «Wiring Repairs»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

Ignition ON, observe the scan tool Ambient Light Sensor parameter. The reading should be between 1.4-4.5 V and change with ambient light changes.

  1. Ignition OFF, disconnect the harness connector at the B10 ambient light/sunload sensor.
  2. Ignition OFF, scan tool disconnected, interior lamps OFF, doors CLOSED, test for less than 10 ohms between the ground circuit terminal 6 and ground. If greater than the specified value, test the ground circuit for an open/high resistance.
  3. Ignition ON, verify the scan tool Ambient Light Sensor parameter is greater than 4.65 V. If less than the specified range, test the signal circuit terminal 5 for a short to ground. If the circuit tests normal, replace the K9 BCM.
  4. Install a 3 A fused jumper wire between the signal circuit terminal 5 and ground. Verify the scan tool Ambient Light Sensor parameter is less than 0.196 V. If greater than the specified range, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the K9 BCM.
  5. If all circuits test normal, replace the B10 ambient light/sunload sensor.

Static Test

  1. Ignition ON, observe the scan tool Ambient Light Sensor parameter. The reading should be between 1.4-4.5 V and change with ambient light changes.
  2. Test the B10B Ambient Light/Sunload Sensor by varying the ambient light while monitoring the sensors voltage output.
  3. Verify that the voltage output is within the range of the specification. If not within the specified range, replace the B10B Ambient Light/Sunload Sensor.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

  1. «Headlamp Automatic Control Ambient Light Sensor Replacement»(/buick/regal/v-2009-2013/remont/exterior-lights/#lighting-system)
  2. «Control Module References»(/buick/regal/v-2009-2013/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for BCM replacement, programming and setup
  1. Perform the «Diagnostic System Check - Vehicle»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
  3. «Diagnostic Procedure Instructions»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.
CircuitShort to GroundOpen/High ResistanceShort to VoltageSignal Performance
Interior Accent Light ControlB2652 0221
1. Interior Accent Light at Full Intensity and Does Not Dim 2. Interior Accent Light Do Not Illuminate

The body control module (BCM) uses the ambient light sensor to determine which brightness of the accent lighting is needed. The BCM applies a pulse width modulated (PWM) voltage through the accent light LED control circuit. Depending on the specified lighting requirements, the BCM has three different accent lighting settings

  1. Daylight Conditions (70%)
  2. Night Conditions (40%)
  3. Welcome Light Illumination (100%)
  1. The ignition is ON.
  2. The headlamps or park lamps ON.

The BCM detects a short to ground on the accent lighting control circuit.

The BCM does not attempt to illuminate the accent lighting.

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

Schematic Reference

Connector End View Reference

Description and Operation

Electrical Information Reference

  1. «Circuit Testing»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «Testing for Intermittent Conditions and Poor Connections»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
  4. «Wiring Repairs»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

When opening the driver door, the accent lighting should turn ON. When closing the driver door and locking the vehicle, the accent lighting should turn OFF after 5 seconds.

  1. Ignition OFF, disconnect the harness connector at any component with inoperative backlighting.
  2. Ignition OFF, scan tool disconnected, interior lamps OFF, doors CLOSED, test for less than 5 ohms between the ground circuit and ground. If greater than the specified value, test the ground circuit for an open/high resistance.
  3. Connect a test lamp between the control circuit and ground.
  4. Command the Incandescent Dimming ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states. If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the K9 BCM. If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the K9 BCM.
  5. If all circuits test normal, test or replace the component with the inoperative backlighting.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

  1. Refer to the appropriate replacement procedure for the component causing the condition.
  2. «Control Module References»(/buick/regal/v-2009-2013/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for BCM replacement, programming and setup
  1. Perform the «Diagnostic System Check - Vehicle»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
  3. «Diagnostic Procedure Instructions»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.
CircuitShort to GroundOpen/High ResistanceShort to VoltageSignal Performance
Front Fog Lamps Switch SignalB2740 00

The front fog lamp relay is supplied with battery voltage at all times. The front fog lamp switch signal circuit is grounded momentarily by pressing the front fog lamp switch. The body control module (BCM) energizes the front fog lamp relay by applying ground to the front fog lamp relay control circuit. When the front fog lamp relay is energized, the relay switch contacts close and battery voltage is applied through the front fog lamp fuse to the front fog lamp supply voltage circuit, which illuminates the front fog lamps.

  1. The ignition is turned ON.
  2. Front fog lamp switch activated.

The front fog lamps malfunction.

The front fog lamp switch is stuck on for more than 60 seconds.

The condition for setting the DTC is not longer present.

Schematic Reference

Connector End View Reference

Description and Operation

Electrical Information Reference

  1. «Circuit Testing»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «Testing for Intermittent Conditions and Poor Connections»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
  4. «Wiring Repairs»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

Ignition ON, observe the scan tool Front Fog Lamps Switch parameter while pressing and releasing the front fog lamps switch. The parameter should change between Active and Inactive when changing between the selected states.

  1. Ignition OFF, disconnect the harness connector at the S30 headlamp switch.
  2. Ignition ON, verify that a test lamp illuminates between the 12 V reference circuit terminal 1 and ground. If the test lamp does not illuminate, test the 12 V reference circuit for a short to ground or an open/high resistance. If the circuit tests normal and the circuit fuse is open, test the signal circuit terminal 12 for a short to ground.
  3. Verify the scan tool Front Fog Lamps Switch parameter is Inactive. If not the specified value, test the signal circuit terminal 12 for a short to voltage. If the circuit tests normal, replace the K9 BCM.
  4. Install a 3 A fused jumper wire between the signal circuit terminal 12 and the 12 V reference circuit terminal 1. Verify the scan tool Front Fog Lamps Switch parameter is Active. If not the specified value, test the signal circuit for an open/high resistance. If the circuit tests normal, replace the K9 BCM.
  5. If all circuits test normal, test or replace the S30 headlamp switch.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

  1. «Headlamp Switch Replacement»(/buick/regal/v-2009-2013/remont/exterior-lights/#lighting-system)
  2. «Control Module References»(/buick/regal/v-2009-2013/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for BCM replacement, programming and setup
  1. Perform the «Diagnostic System Check - Vehicle»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
  3. «Diagnostic Procedure Instructions»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.
CircuitShort to GroundOpen/High ResistanceShort to VoltageSignal Performance
Hazard Switch SignalB3596 00, 211B3596 00
Hazard Switch Ground1
1. Hazard Lamps Inoperative 2. Hazard Lamps Always ON

The hazard flashers may be activated in any power mode. The hazard warning switch is permanently grounded. When the hazard warning switch is placed in the ON position, ground is applied through the hazard warning switch signal circuit to the body control module (BCM). The BCM supplies battery voltage to all turn signal lamps in an ON and OFF duty cycle.

Ignition is ON.

Hazard warning switch stuck for more than 1 minute.

Hazard flashers malfunction.

The condition for setting the DTC is no longer present.

Schematic Reference

Connector End View Reference

Description and Operation

Electrical Information Reference

  1. «Circuit Testing»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «Testing for Intermittent Conditions and Poor Connections»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
  4. «Wiring Repairs»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

Ignition ON, observe the scan tool Hazard Lamps Switch parameter while pressing and releasing the hazard switch. The parameter should change between Active and Inactive when changing between the selected states.

  1. Ignition OFF, disconnect the harness connector at the S48C multifunction switch 1-instrument panel.
  2. Ignition OFF and all vehicle systems OFF. It may take up to 2 minutes for all vehicle systems to power down. Test for less than 10 ohms between the ground circuit terminal 7 and ground. If greater than the specified range, test the ground circuit for an open/high resistance.
  3. Ignition ON, verify the scan tool Hazard Lamps Switch parameter is Inactive. If not the specified value, test the signal circuit terminal 10 for a short to ground. If the circuits tests normal, replace the K9 BCM.
  4. Install a 3 A fused jumper wire between the signal circuit terminal 10 and the ground circuit terminal 7. Verify the scan tool Hazard Lamps Switch parameter is Active. If not the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the K9 BCM.
  5. If all circuits test normal, test or replace the S48C multifunction switch 1-instrument panel.

Perform the Diagnostic Repair Verification after completing the repair.

  1. «Hazard Warning Switch Replacement»(/buick/regal/v-2009-2013/remont/exterior-lights/#lighting-system)
  2. «Control Module References»(/buick/regal/v-2009-2013/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for BCM replacement, programming and setup
  1. Perform the «Diagnostic System Check - Vehicle»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
  3. «Diagnostic Procedure Instructions»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.
CircuitShort to GroundOpen/High ResistanceShort to VoltageSignal Performance
Headlamp High Beam SignalB3650 0811
Headlamp Flash To Pass SignalB3806 0022
Turn Signal/Multifunction Switch Ground1, 2
1. Headlamp Dimmer Switch Malfunction 2. Headlamp Flash To Pass Switch Malfunction

The BCM monitors the voltage level within the high beam signal circuit and the flash to pass signal circuit. When the turn signal/multifunction switch is moved to the high beam position or to the flash to pass position, the voltage within the appropriate signal circuit drops to less than 1 V. The BCM will detect the voltage drop and will command the headlamp high beams to turn ON or OFF.

Battery voltage must be between 9-16 V.

The BCM detects a short to ground in the headlamp high beam signal circuit.

The high beam headlamps will malfunction.

  1. The DTC will be current for as long as the fault is present.
  2. When the fault is no longer present, the DTC will be a history DTC.
  3. A history DTC will clear after 50 ignition cycles.

Schematic Reference

Connector End View Reference

Description and Operation

Electrical Information Reference

  1. «Circuit Testing»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «Testing for Intermittent Conditions and Poor Connections»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
  4. «Wiring Repairs»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

Ignition ON, observe the scan tool High Beam Select Switch parameter while pulling and releasing the turn signal/multi-function switch. The value should change between Inactive and Active when changing between the selected states.

  1. Ignition OFF, disconnect at the S78 turn signal/multifunction switch.
  2. Ignition ON, verify that the scan tool High Beam Select Switch parameter is Inactive. If not the specified value, test the signal circuit terminal 2 for a short to ground. If the circuit tests normal, replace the K9 BCM.
  3. Connect a 3 A fused jumper wire between the signal circuit terminal 2 and ground, verify that the scan tool High Beam Select Switch parameter is Active. If not the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the K9 BCM.
  4. If all circuits test normal, test or replace the S78 turn signal/multifunction switch.

Turn Signal/Multifunction Switch Test

  1. Ignition OFF, disconnect the harness connector at the S78 turn signal/multifunction switch.
  2. Test for Infinite resistance between the terminals listed below with the switch in the open position. Signal terminal 2 and ground terminal 3 Signal terminal 4 and ground terminal 3 If not the specified value, replace the S78 turn signal/multifunction switch.
  3. Test for less than 2 ohms between the signal terminal 2 and the ground terminal 3 with the switch in the high beam position. If greater than the specified value, replace the S78 turn signal/multifunction switch.
  4. Test for less than 2 ohms between the signal terminal 4 and the ground terminal 3 while holding the switch in the flash to pass position. If greater than the specified value, replace the S78 turn signal/multifunction switch.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

  1. «Turn Signal Multifunction Switch Replacement»(/buick/regal/v-2009-2013/remont/steering-column-switches/#steering-wheel-and-steering-column)
  2. «Control Module References»(/buick/regal/v-2009-2013/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for BCM replacement, programming and setup
  1. Perform the «Diagnostic System Check - Vehicle»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
  3. «Diagnostic Procedure Instructions»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.
CircuitShort to GroundOpen/High ResistanceShort to VoltageSignal Performance
Headlamp High Beam SignalB3650 0811
Headlamp Flash To Pass SignalB3806 0022
Turn Signal/Multifunction Switch Ground1, 2
1. Headlamp Dimmer Switch Malfunction 2. Headlamp Flash To Pass Switch Malfunction

The BCM monitors the voltage level within the high beam signal circuit and the flash to pass signal circuit. When the turn signal/multifunction switch is moved to the high beam position or to the flash to pass position, the voltage within the appropriate signal circuit drops to less than 1 V. The BCM will detect the voltage drop and will command the headlamp high beams to turn ON or OFF.

Battery voltage must be between 9-16 V.

The BCM detects a short to ground in the headlamp flash to pass signal circuit for greater than 15 seconds.

The high beam headlamps will malfunction.

  1. The DTC will be current for as long as the fault is present.
  2. When the fault is no longer present, the DTC will be a history DTC.
  3. A history DTC will clear after 50 ignition cycles.

Schematic Reference

Connector End View Reference

Description and Operation

Electrical Information Reference

  1. «Circuit Testing»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «Testing for Intermittent Conditions and Poor Connections»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
  4. «Wiring Repairs»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

Ignition ON, observe the scan tool Headlamps Flash Switch parameter while pulling and releasing the turn signal/multifunction switch. The value should change between Inactive and Active when changing between the selected states.

  1. Ignition OFF, disconnect at the S78 turn signal/multifunction switch.
  2. Ignition ON, verify that the scan tool Headlamps Flash Switch parameter is Inactive. If not the specified value, test the signal circuit terminal 4 for a short to ground. If the circuit tests normal, replace the K9 BCM.
  3. Connect a 3 A fused jumper wire between the signal circuit terminal 4 and ground, verify that the scan tool Headlamps Flash Switch parameter is Active. If not the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the K9 BCM.
  4. If all circuits test normal, test or replace the S78 turn signal/multifunction switch.

Turn Signal/Multifunction Switch Test

  1. Ignition OFF, disconnect the harness connector at the S78 turn signal/multifunction switch.
  2. Test for Infinite resistance between the terminals listed below with the switch in the open position. Signal terminal 2 and ground terminal 3 Signal terminal 4 and ground terminal 3 If not the specified value, replace the S78 turn signal/multifunction switch.
  3. Test for less than 2 ohms between the signal terminal 2 and the ground terminal 3 with the switch in the high beam position. If greater than the specified value, replace the S78 turn signal/multifunction switch.
  4. Test for less than 2 ohms between the signal terminal 4 and the ground terminal 3 while holding the switch in the flash to pass position. If greater than the specified value, replace the S78 turn signal/multifunction switch.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

  1. «Turn Signal Multifunction Switch Replacement»(/buick/regal/v-2009-2013/remont/steering-column-switches/#steering-wheel-and-steering-column)
  2. «Control Module References»(/buick/regal/v-2009-2013/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for BCM replacement, programming and setup
  1. Perform the «Diagnostic System Check - Vehicle»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
  3. «Diagnostic Procedure Instructions»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.
CircuitShort to GroundOpen/High ResistanceShort to VoltageSignal Performance
Left Tail Lamp Supply VoltageB3881 02B3881 041
Right Tail Lamp Supply VoltageB3882 02B3882 041
1. Tail Lamp Malfunction

The body control module (BCM) energizes the tail lamps by applying voltage to the tail lamp control circuit. When the tail lamp control circuit is energized, the tail lamps are illuminated.

Headlamp switch in park or low beam position.

B3881 02

The BCM detects a short to ground on the left park lamp supply voltage circuit.

B3881 04

The BCM detects an open/high resistance on the left park lamp supply voltage circuit

B3882 02

The BCM detects a short to ground on the right park lamp supply voltage circuit.

B3882 04

The BCM detects an open/high resistance on the right park lamp supply voltage circuit

The appropriate tail lamp will be inoperative.

  1. The DTC will be current for as long as the fault is present.
  2. When the fault is no longer present, the DTC will be a history DTC.
  3. A history DTC will clear after 50 ignition cycles.

Schematic Reference

Connector End View Reference

Description and Operation

Electrical Information Reference

  1. «Circuit Testing»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «Testing for Intermittent Conditions and Poor Connections»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
  4. «Wiring Repairs»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

Ignition ON, command the Left Park Lamps ON and OFF with a scan tool. The park lamps should turn ON and OFF while changing between the commanded states.

  1. Ignition OFF, disconnect the harness connector at the appropriate E42 tail lamp assembly.
  2. Ignition OFF and all vehicle systems OFF. It may take up to 2 minutes for all vehicle systems to power down. Test for less than 10 ohms between the ground circuit terminal F and ground. If greater than the specified range, test the ground circuit for an open/high resistance.
  3. Connect a test lamp between the control circuit terminal A and the ground circuit terminal F.
  4. Command the Park Lamps ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states. If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the K9 BCM. If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the K9 BCM.
  5. If all circuits test normal, test or replace the E42 tail lamp assembly.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

  1. «Tail Lamp Bulb Replacement»(/buick/regal/v-2009-2013/remont/exterior-lights/#lighting-system)
  2. «Control Module References»(/buick/regal/v-2009-2013/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for BCM replacement, programming and setup
  1. Perform the «Diagnostic System Check - Vehicle»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
  3. «Diagnostic Procedure Instructions»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.
CircuitShort to GroundOpen/High ResistanceShort to VoltageSignal Performance
License Plate Lamp ControlB3883 02B3883 041
License Plate Lamp Ground2
1. License Plate Lamps Always ON 2. License Plate Lamps Always OFF

The headlamp switch is supplied with ground at all times. When the headlamp switch is placed in either the park or low beam position, ground is applied to the license plate lamp signal circuit to the body control module (BCM). The BCM responds by applying battery voltage to the license plate lamp control circuit. This energizes the left and right license lamps.

Headlamp switch in park or low beam position

B3883 02

The BCM detects a short to ground on the license plate lamp control circuit.

B3883 04

The BCM detects an open circuit on the license plate lamp control circuit.

The appropriate license plate lamp is inoperative.

The condition for setting the DTC is no longer present.

Schematic Reference

Connector End View Reference

Description and Operation

Electrical Information Reference

  1. «Circuit Testing»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «Testing for Intermittent Conditions and Poor Connections»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
  4. «Wiring Repairs»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

Ignition ON, turn the headlamp switch between the PARK and OFF positions. The license plate lamps should turn ON and OFF when changing between the selected states.

  1. Ignition OFF, disconnect the harness connector at the appropriate E7 license plate lamp.
  2. Test for less than 30 ohms between the ground circuit terminal 2 and ground. If greater than the specified value, test the ground circuit for an open/high resistance.
  3. Connect a test lamp between the control circuit terminal 1 and ground.
  4. Turn the license plate lamps ON and OFF using the headlamp switch. The test lamp should turn ON and OFF when changing between the selected states. If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the K9 BCM. If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the K9 BCM.
  5. If all circuits test normal, test or replace the E7 license plate lamp.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

  1. «Rear License Plate Lamp Replacement»(/buick/regal/v-2009-2013/remont/exterior-lights/#lighting-system)
  2. «Rear License Plate Lamp Bulb Replacement»(/buick/regal/v-2009-2013/remont/exterior-lights/#lighting-system)
  3. «Control Module References»(/buick/regal/v-2009-2013/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for BCM replacement, programming and setup
  1. Perform the «Diagnostic System Check - Vehicle»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
  3. «Diagnostic Procedure Instructions»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.
CircuitShort to GroundOpen/High ResistanceShort to VoltageSignal Performance
Center High Mounted Brake Lamp ControlB3884 02B3884 041
Center High Mounted Brake Lamp Ground2
1. Center High Mounted Brake Lamp Always ON 2. Center High Mounted Brake Lamp Always OFF

The brake pedal position sensor is used to sense the action of the driver application of the brake pedal. The brake pedal position sensor provides an analog voltage signal to the body control module (BCM). The BCM will apply battery voltage to the right, left and center stop lamp control circuits.

The brakes are applied.

B3884 02

The BCM detects a short to ground on the center high mounted brake lamp control circuit.

B3884 04

The BCM detects an open circuit on the center high mounted brake lamp control circuit.

The center high mounted brake lamp will not illuminate.

  1. The DTC will be current for as long as the fault is present.
  2. When the fault is no longer present, the DTC will be a history DTC.
  3. A history DTC will clear after 50 ignition cycles.

Schematic Reference

Connector End View Reference

Description and Operation

Electrical Information Reference

  1. «Circuit Testing»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «Testing for Intermittent Conditions and Poor Connections»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
  4. «Wiring Repairs»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

Ignition ON, turn the center high mounted brake lamp ON and OFF by applying and releasing the brake pedal. The center high mounted brake lamp should turn ON and OFF when changing between the selected states.

  1. Ignition OFF, disconnect the harness connector at the E6 center high mounted stop lamp.
  2. Test for less than 30 ohms between the ground circuit terminal 1 and ground. If greater than the specified value, test the ground circuit for an open/high resistance.
  3. Connect a test lamp between the control circuit terminal 2 and ground.
  4. Ignition ON, turn the center high mounted stop lamp ON and OFF by applying and releasing the brake pedal. The test lamp should turn ON and OFF when changing between the selected states. If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the K9 BCM. If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the K9 BCM.
  5. If all circuits test normal, replace the E6 center high mounted stop lamp.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

  1. «High Mount Stop Lamp Replacement»(/buick/regal/v-2009-2013/remont/exterior-lights/#lighting-system)
  2. «Control Module References»(/buick/regal/v-2009-2013/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for BCM replacement, programming and setup
  1. Perform the «Diagnostic System Check - Vehicle»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
  3. «Diagnostic Procedure Instructions»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.
CircuitShort to GroundOpen/High ResistanceShort to VoltageSignal Performance
Left Front Turn Signal ControlB3948 02B3948 042
Right Front Turn Signal ControlB3949 02B3949 042
Turn Signal Ground1
Repeater Lamp Ground3
1. Turn Signal Lamp Inoperative 2. Turn Signal Lamp Always ON 3. Repeater Lamp Inoperative

Ground is applied at all times to the turn signal/multifunction switch. When the turn signal/multifunction switch is placed in either the turn right or turn left position, ground is applied to the body control module (BCM) through either the right turn or left turn signal switch signal circuit. The BCM then applies a voltage to the front and side signal lamps through their respective voltage supply circuits.

The appropriate turn signal is active.

B3948 02

The BCM detects a short to ground on the left front turn signal control circuit.

B3948 04

The BCM detects an open/high resistance on the left front turn signal control circuit.

B3949 02

The BCM detects a short to ground on the right front turn signal control circuit.

B3949 04

The BCM detects an open/high resistance on the right front turn signal control circuit.

B3948 02 or B3948 04

The left front turn signal will be inoperative.

B3949 02 or B3949 04

The right front turn signal will be inoperative.

  1. The DTC will be current for as long as the fault is present.
  2. When the fault is no longer present, the DTC will be a history DTC.
  3. A history DTC will clear after 50 ignition cycles.

Diagnostic Aids

The vehicle may be equipped with the RPO DLG/DLL driver and passenger outside rearview mirrors which contains turn signal repeater lamps, the lamps share the same control circuits as the front park/turn signal lamps.

Schematic Reference

Connector End View Reference

Description and Operation

Electrical Information Reference

  1. «Circuit Testing»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «Testing for Intermittent Conditions and Poor Connections»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
  4. «Wiring Repairs»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

Ignition ON, command the Front Turn Signal Lamp ON and OFF with a scan tool. The appropriate front turn signal lamp should turn ON and OFF while changing between the commanded states.

  1. Ignition OFF, disconnect the harness connector at the appropriate E4 turn signal lamp.
  2. Test for less than 30 ohms between the ground circuit terminal listed below and ground: Turn signal lamp - front - terminal 1 Turn signal repeater lamp - terminal 2 If greater than the specified value, test the ground circuit for an open/high resistance.
  3. Connect a test lamp between the control circuit terminal listed below and ground: Turn signal lamp - front - terminal 5 Turn signal repeater lamp - terminal 1
  4. Command the appropriate Front Turn Signal Lamp ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states. If the test lamp is always ON, test the signal circuit for a short to voltage. If the circuit tests normal, replace the K9 BCM. If the test lamp is always OFF, test the signal circuit for a short to ground or an open/high resistance. If the circuits test normal, replace the K9 BCM.
  5. If all circuits test normal, replace the E4 turn signal lamp.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

  1. «Front Side Turn Signal Lamp Replacement»(/buick/regal/v-2009-2013/remont/exterior-lights/#lighting-system)
  2. «Front Turn Signal Lamp Bulb Replacement»(/buick/regal/v-2009-2013/remont/exterior-lights/#lighting-system)
  3. «Outside Rearview Mirror Replacement»(/buick/regal/v-2009-2013/remont/mirrors/#mirror-system)
  4. «Control Module References»(/buick/regal/v-2009-2013/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for BCM replacement, programming and setup
  1. Perform the «Diagnostic System Check - Vehicle»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
  3. «Diagnostic Procedure Instructions»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.
CircuitShort to GroundOpen/High ResistanceShort to VoltageSignal Performance
Left Rear Turn Signal ControlB3950 02B3950 041
Right Rear Turn Signal ControlB3951 02B3951 041
Left Rear Turn Signal Ground2
Right Rear Turn Signal Ground2
1. Rear Turn Signal Lamp Always ON 2. Rear Turn Signal Lamp Always OFF

Ground is applied at all times to the turn signal/multifunction switch. When the turn signal/multifunction switch is placed in either the turn right or turn left position, ground is applied to the body control module (BCM) through either the right turn or left turn signal switch signal circuit. The BCM then applies a voltage to the rear turn signal lamps through their respective voltage supply circuits.

The appropriate rear turn signal is active.

B3950 02 or B3951 02

The BCM detects a short to ground on the appropriate rear turn signal control circuit.

B3950 04 or B3951 04

The BCM detects an open circuit on the appropriate rear turn signal control circuit.

The appropriate rear turn signal lamp is inoperative.

The condition for setting the DTC is no longer present.

Schematic Reference

Connector End View Reference

Description and Operation

Electrical Information Reference

  1. «Circuit Testing»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «Testing for Intermittent Conditions and Poor Connections»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
  4. «Wiring Repairs»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

Ignition ON, command the appropriate Rear Turn Signal Lamp ON and OFF with a scan tool. The rear turn signal lamp should turn ON and OFF when changing between the commanded states.

Note. If DTC B3950 02 or B3951 02 are set fuse block underhood BCM fuse 32 may be open. Test circuit and fuse before replacing BCM.

  1. Ignition OFF, disconnect the harness connector at the appropriate E4 turn signal lamp.
  2. Test for less than 5 ohms between the ground circuit terminal F and ground. If greater than the specified value, test the ground circuit for an open/high resistance.
  3. Connect a test lamp between the control circuit terminal B and ground.
  4. Command the appropriate Rear Turn Signal Lamp ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states. If the test lamp is always ON, test the signal circuit for a short to voltage. If the circuit tests normal, replace the K9 BCM. If the test lamp is always OFF, test the signal circuit for a short to ground or an open/high resistance. If the circuits test normal, replace the K9 BCM.
  5. If all the circuits test normal, replace the E4 turn signal lamp.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

  1. «Tail Lamp Bulb Replacement»(/buick/regal/v-2009-2013/remont/exterior-lights/#lighting-system)
  2. «Tail Lamp Replacement»(/buick/regal/v-2009-2013/remont/exterior-lights/#lighting-system)
  3. «Control Module References»(/buick/regal/v-2009-2013/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for BCM replacement, programming and setup
  1. Perform the «Diagnostic System Check - Vehicle»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
  3. «Diagnostic Procedure Instructions»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.
CircuitShort to GroundOpen/High ResistanceShort to VoltageSignal Performance
F32UA Fuse B+B2545 01, B2545 04B2545 01, B2545 04
Backup Lamp Switch Signal111C0010 5A
Backup Lamps ControlB2545 02B2545 01, B2545 041
Backup Lamp - Left Ground1
Backup Lamp - Right Ground1
Backup Lamp Switch Ground1
1. Backup Lamps Malfunction

The engine control module (ECM) provides a signal circuit to the backup lamp switch which is permanently grounded. With the engine ON and the transmission in the REVERSE position, the backup lamp switch signal circuit is pulled low and the ECM responds by sending a serial data message to the body control module (BCM). The message indicates that the gear selector is in the REVERSE position. The BCM applies battery voltage to the backup lamps control circuit illuminating the backup lamps. Once the driver moves the gear selector out of the REVERSE position, a message is sent by the ECM via serial data requesting the BCM to remove battery voltage from the backup lamps control circuit. The engine must be ON for the backup lamps to operate.

  1. Battery voltage must be between 9-16 V.
  2. Engine ON.

The ECM detects a stuck backup lamp switch.

  1. The condition for setting the DTC is no longer present.
  2. A history DTC will clear once 50 malfunction-free ignition cycles have occurred.

Schematic Reference

Connector End View Reference

Description and Operation

Electrical Information Reference

  1. «Circuit Testing»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «Testing for Intermittent Conditions and Poor Connections»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
  4. «Wiring Repairs»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

  1. Ignition OFF, disconnect the harness connector at the B16 backup lamp switch.
  2. Ignition OFF, exterior lamps OFF, doors CLOSED, wait 30 seconds, test for less than 5 ohms between the ground circuit terminal 2 and ground. If greater than the specified range, test the ground circuit for an open/high resistance.
  3. Ignition ON, verify the scan tool Reverse Position Switch parameter is OFF. If not the specified value, test the signal circuit terminal 1 for a short to ground. If the circuit tests normal, replace the K20 engine control module.
  4. Install a 3 A fused jumper wire between the signal circuit terminal 1 and the ground circuit terminal 2. Verify the scan tool Reverse Position Switch parameter is ON. If not the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the K20 engine control module.
  5. If all circuits test normal, replace the B16 backup lamp switch.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

  1. «Backup Lamp Switch Replacement»(/buick/regal/v-2009-2013/remont/manual-trans/#manual-transmission-f40)
  2. «Control Module References»(/buick/regal/v-2009-2013/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for BCM replacement, setup and programming
  1. Perform the «Diagnostic System Check - Vehicle»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
  3. «Diagnostic Procedure Instructions»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.
CircuitShort to GroundOpen/High ResistanceShort to VoltageSignal Performance
5 V ReferenceC0277 06, C0561 71, C0890 03, U0140 71C0277 06, C0561 71, U0140 71C0890 07, C0561 71, U0140 71
SignalC0277 06, C0561 71, U0140 71C0277 06, C0561 71, U0140 71C0277 07, C0890 07C0277 09
Low ReferenceC0277 07, C0561 71, U0140 71

The brake pedal position sensor is used to sense the action of the driver application of the brake pedal. The brake pedal position sensor provides an analog voltage signal that will increase as the brake pedal is applied. The body control module provides a low reference signal and a 5 V reference voltage to the brake pedal position sensor. When the variable signal reaches a voltage threshold indicating the brakes have been applied, the BCM will apply battery voltage to the stop lamp control circuit and center high mounted stop lamp control circuit. When the control circuit is energized the stop lamps are illuminated.

  1. Battery voltage must be between 9-16 V
  2. Brakes applied

C0277 06 or C0890 03

  1. The BCM detects a short to ground or an open/high resistance in the brake pedal position sensor signal circuit.
  2. The BCM detects a short to ground or an open/high resistance in the brake pedal position sensor 5 V reference circuit.

C0277 07 or C0890 07

  1. The BCM detects a short to battery voltage in the brake pedal position sensor signal circuit.
  2. The BCM detects an open/high resistance in the brake pedal position sensor low reference circuit.

C0277 09

The BCM detects the brake pedal position sensor signal is changing faster than possible under normal operating conditions.

C0277 4B

The brake pedal position sensor home position is not learned.

Brake lights will malfunction, the shift lock is inoperative, the service park brake system lamp illuminated in IPC, park brake will set but not disengage

  1. The DTC will be current for as long as the fault is present.
  2. When the fault is no longer present, the DTC will be a history DTC.
  3. A history DTC will clear after 50 ignition cycles.

C0277 4B

If the DTC is set, recalibrate the brake pedal position sensor.

C0277 09

If the DTC is set, replace the brake pedal position sensor. If the DTC resets, replace the BCM.

Schematic Reference

Connector End View Reference

Description and Operation

Electrical Information Reference

  1. «Circuit Testing»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «Testing for Intermittent Conditions and Poor Connections»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
  4. «Wiring Repairs»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

C0277 06, C0277 07, C0890 03, C0890 07

  1. Ignition OFF, disconnect the harness connector at the B22 brake pedal position sensor.
  2. Ignition OFF, test for less than 60 ohms between the low reference circuit terminal C and ground. If greater than the specified range, test the low reference circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the K9 BCM.
  3. Ignition ON, test for 4.8-5.2 V between the 5 V reference circuit terminal A and ground. If less than the specified range, test the 5 V reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the K9 BCM. If greater than the specified range, test the 5 V reference circuit for a short to voltage. If the circuit tests normal, replace the K9 BCM.
  4. Verify that the scan tool Brake Pedal Position Sensor parameter is less than 0.3 V. If greater than the specified range, test the signal circuit terminal B for a short to voltage. If the circuit tests normal, replace the K9 BCM.
  5. Connect a 3 A fused jumper wire between the 5 V reference circuit terminal A and the signal circuit terminal B. Verify that the scan tool Brake Pedal Position Sensor parameter is 4.8-5.2 V If less than the specified range, test the signal circuit for short to ground or an open/high resistance. If the circuit tests normal, replace the K9 BCM.
  6. If all circuits test normal, test or replace the B22 brake pedal position sensor.

C0277 09

  1. Replace the B22 BPP sensor.
  2. Perform the BPP sensor recalibration procedure. Refer to «Brake Pedal Position Sensor Calibration»(/buick/regal/v-2009-2013/remont/exterior-lights/#lighting-system__brake-pedal-position-sensor-calibration) .
  3. Operate the vehicle within the Conditions for Running and Setting the DTC and verify the DTC does not reset. If the DTC resets, replace the K9 BCM.

C0277 4B

  1. Verify that the DTC sets under the Conditions for Running and Setting.
  2. Perform the BPP sensor recalibration procedure. Refer to «Brake Pedal Position Sensor Calibration»(/buick/regal/v-2009-2013/remont/exterior-lights/#lighting-system__brake-pedal-position-sensor-calibration) .
  3. Operate the vehicle within the conditions that the customer experienced and verify the DTC does not reset. If the DTC resets, replace the B22 BPP sensor.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

  1. «Brake Pedal Position Sensor Calibration»(/buick/regal/v-2009-2013/remont/exterior-lights/#lighting-system__brake-pedal-position-sensor-calibration)
  2. «Brake Pedal Position Sensor Replacement»(/buick/regal/v-2009-2013/remont/exterior-lights/#lighting-system__brake-pedal-position-sensor-replacement)
  3. «Control Module References»(/buick/regal/v-2009-2013/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for BCM replacement, programming and setup
  1. Perform the «Diagnostic System Check - Vehicle»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
  3. «Diagnostic Procedure Instructions»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.
CircuitShort to GroundOpen/High ResistanceShort to VoltageSignal Performance
Cruise/ETC/TCC Brake SignalC0297 02, P0572P0572P0573P0571

The stop lamp switch signal circuit is a B+ input from the body control module (BCM) to the engine control module (ECM). The ECM monitors the stop lamp switch circuit to detect when the brake pedal has been applied. The BCM monitors the brake pedal position sensor to determine when the brake pedal is applied. When the brake pedal is applied, the BCM supplies 12V on the stop lamp switch signal circuit and also sends a serial data message to the ECM indicating that the brake pedal has been applied.

The ignition is ON.

The BCM detects a short to ground on the cruise/ETC/TCC brake signal circuit.

The cruise control system is disabled

  1. The DTC will be current for as long as the fault is present.
  2. When the fault is no longer present, the DTC will be a history DTC.
  3. A history DTC will clear after 50 ignition cycles.

Schematic Reference

Connector End View Reference

Description and Operation

  1. «Cruise Control Description and Operation»(/buick/regal/v-2009-2013/remont/cruise-control-systems/#cruise-control-system__cruise-control-description-and-operation)
  2. «Exterior Lighting Systems Description and Operation»(/buick/regal/v-2009-2013/remont/exterior-lights/#lighting-system)

Electrical Information Reference

  1. «Circuit Testing»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «Testing for Intermittent Conditions and Poor Connections»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
  4. «Wiring Repairs»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

  1. Ignition OFF, disconnect the X1 (LAF/LF1) or X2 (LLT) harness connector at the K20 ECM.
  2. Connect a test lamp between the signal circuit terminal listed below and ground: Terminal 57 (LAF/LF1) Terminal 52 (LLT)
  3. Ignition ON, observe the function of the test lamp while pressing and releasing the brake pedal. The test lamp should turn ON when the brake pedal is pressed and turn OFF when the brake pedal is released. If the test lamp is always ON, test the signal circuit for a short to voltage. If the test lamp is always OFF, test the signal circuit for a short to ground or an open/high resistance.
  4. If all circuits test normal, replace the K9 BCM.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for BCM replacement, setup and programming

Symptoms - Lighting

Note. The following steps must be completed before using a symptom table.

  1. Perform the «Diagnostic System Check - Vehicle»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) before using a symptom table in order to verify that all of the following conditions are true: There are no DTCs set. The control modules can communicate via the serial data link.
  2. Review the system description and operation in order to familiarize yourself with the system functions. Refer to the following: «Exterior Lighting Systems Description and Operation»(/buick/regal/v-2009-2013/remont/exterior-lights/#lighting-system) «Interior Lighting Systems Description and Operation»(/buick/regal/v-2009-2013/remont/exterior-lights/#lighting-system)

Visual/Physical Inspection

  1. Inspect for aftermarket devices which could affect the operation of the lighting system. Refer to «Checking Aftermarket Accessories»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__checking-aftermarket-accessories) .
  2. Inspect the easily accessible or visible system components for obvious damage or conditions which could cause the symptom.

Intermittent

Thoroughly inspect the wiring and connectors. An incomplete inspection of the wiring and connectors may result in misdiagnosis causing part replacement with the reappearance of the malfunction. If an intermittent malfunction exists, refer to Testing for Intermittent Conditions and Poor Connections .

Symptom List

Refer to a symptom diagnostic procedure from the following list in order to diagnose the symptom

  1. «Backup Lamps Malfunction (Automatic Transmission)»(/buick/regal/v-2009-2013/remont/exterior-lights/#lighting-system) , «Backup Lamps Malfunction (Manual Transmission)»(/buick/regal/v-2009-2013/remont/exterior-lights/#lighting-system)
  2. «Courtesy Lamps Malfunction»(/buick/regal/v-2009-2013/remont/exterior-lights/#lighting-system)
  3. «Front Fog Lamps Malfunction»(/buick/regal/v-2009-2013/remont/exterior-lights/#lighting-system)
  4. «Hazard Lamps Malfunction»(/buick/regal/v-2009-2013/remont/exterior-lights/#lighting-system)
  5. «Headlamps Malfunction»(/buick/regal/v-2009-2013/remont/exterior-lights/#lighting-system)
  6. «Interior Accent Lighting Malfunction»(/buick/regal/v-2009-2013/remont/exterior-lights/#lighting-system)
  7. «Interior Backlighting Malfunction»(/buick/regal/v-2009-2013/remont/exterior-lights/#lighting-system)
  8. «Park, License, and/or Tail Lamps Malfunction»(/buick/regal/v-2009-2013/remont/exterior-lights/#lighting-system)
  9. «Stop Lamps Malfunction»(/buick/regal/v-2009-2013/remont/exterior-lights/#lighting-system)
  10. «Turn Signal Lamps and/or Indicators Malfunction»(/buick/regal/v-2009-2013/remont/exterior-lights/#lighting-system)
  1. Perform the «Diagnostic System Check - Vehicle»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
  3. «Diagnostic Procedure Instructions»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.
CircuitShort to GroundOpen/High ResistanceShort to VoltageSignal Performance
F32UA Fuse B+B2545 01, B2545 04B2545 01, B2545 04
Backup Lamps ControlB2545 02B2545 01, B2545 041
Backup Lamp - Left Ground1
Backup Lamp - Right Ground1
1. Backup Lamps Malfunction

When the engine is running and the transmission is placed in the reverse position, the engine control module (ECM) sends a serial data message to the body control module (BCM). The message indicates that the gear selector is in the reverse position. The BCM applies battery voltage to the backup lamps. The backup lamps are permanently grounded. Once the driver moves the gear selector out of the reverse position, a message is sent by the ECM via serial data requesting the BCM to remove battery voltage from the backup lamp control circuit. The BCM will enable the backup lamps as a courtesy lamp when the doors are unlocked.

Schematic Reference

Connector End View Reference

Description and Operation

Electrical Information Reference

  1. «Circuit Testing»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «Testing for Intermittent Conditions and Poor Connections»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
  4. «Wiring Repairs»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

  1. Ignition OFF, disconnect the harness connector at the appropriate E5 backup lamp.
  2. Ignition OFF, exterior lamps OFF, test for less than 5 ohms between the ground circuit terminal 3 and ground. If greater than the specified range, test the ground circuit for an open/high resistance.
  3. Connect a test lamp between the control circuit terminal 2 and ground.
  4. Ignition ON, command the Backup Lamps ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states. If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the K9 body control module. If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the K9 body control module.
  5. If all circuits test normal, replace the E5 backup lamp.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

  1. «Tail Lamp Replacement»(/buick/regal/v-2009-2013/remont/exterior-lights/#lighting-system)
  2. «Tail Lamp Bulb Replacement»(/buick/regal/v-2009-2013/remont/exterior-lights/#lighting-system)
  3. «Control Module References»(/buick/regal/v-2009-2013/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for BCM replacement, programming and setup
  1. Perform the «Diagnostic System Check - Vehicle»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
  3. «Diagnostic Procedure Instructions»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.
CircuitShort to GroundOpen/High ResistanceShort to VoltageSignal Performance
F32UA Fuse B+B2545 01, B2545 04B2545 01, B2545 04
Backup Lamp Switch Signal111C0010 5A
Backup Lamps ControlB2545 02B2545 01, B2545 041
Backup Lamp - Left Ground1
Backup Lamp - Right Ground1
Backup Lamp Switch Ground1
1. Backup Lamps Malfunction

The engine control module (ECM) provides a signal circuit to the backup lamp switch which is permanently grounded. With the engine ON and the transmission in the REVERSE position, the backup lamp switch signal circuit is pulled low and the ECM responds by sending a serial data message to the body control module (BCM). The message indicates that the gear selector is in the REVERSE position. The BCM applies battery voltage to the backup lamps control circuit illuminating the backup lamps. Once the driver moves the gear selector out of the REVERSE position, a message is sent by the ECM via serial data requesting the BCM to remove battery voltage from the backup lamps control circuit. The engine must be ON for the backup lamps to operate.

Schematic Reference

Connector End View Reference

Description and Operation

Electrical Information Reference

  1. «Circuit Testing»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «Testing for Intermittent Conditions and Poor Connections»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
  4. «Wiring Repairs»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

  1. Engine ON, observe the scan tool Reverse Position Switch parameter in the ECM data list while shifting the vehicle between the neutral and reverse gears. The reading should change between ON and OFF when changing between the selected states. If the reading does not change between the specified values, refer to Backup Lamp Switch Malfunction.
  2. Command the Backup Lamps ON and OFF with a scan tool. The backup lamps should turn ON and OFF when changing between the commanded states. If the backup lamps do not turn ON and OFF when changing between the commanded states, refer to Backup Lamps Malfunction.

Backup Lamp Switch Malfunction

  1. Ignition OFF, disconnect the harness connector at the B16 backup lamp switch.
  2. Ignition OFF, exterior lamps OFF, doors CLOSED, wait 30 seconds, test for less than 5 ohms between the ground circuit terminal 2 and ground. If greater than the specified range, test the ground circuit for an open/high resistance.
  3. Ignition ON, verify the scan tool Reverse Position Switch parameter is OFF. If not the specified value, test the signal circuit terminal 1 for a short to ground. If the circuit tests normal, replace the K20 engine control module.
  4. Install a 3 A fused jumper wire between the signal circuit terminal 1 and the ground circuit terminal 2. Verify the scan tool Reverse Position Switch parameter is ON. If not the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the K20 engine control module.
  5. If all circuits test normal, replace the B16 backup lamp switch.

Backup Lamps Malfunction

  1. Ignition OFF, disconnect the harness connector at the appropriate E5 backup lamp.
  2. Ignition OFF, exterior lamps OFF, test for less than 5 ohms between the ground circuit terminal 3 and ground. If greater than the specified range, test the ground circuit for an open/high resistance.
  3. Connect a test lamp between the control circuit terminal 2 and ground.
  4. Ignition ON, command the Backup Lamps ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states. If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the K9 body control module. If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the K9 body control module.
  5. If all circuits test normal, replace the E5 backup lamp.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

  1. «Tail Lamp Bulb Replacement»(/buick/regal/v-2009-2013/remont/exterior-lights/#lighting-system)
  2. «Backup Lamp Switch Replacement»(/buick/regal/v-2009-2013/remont/manual-trans/#manual-transmission-f40)
  3. «Control Module References»(/buick/regal/v-2009-2013/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for BCM or ECM replacement, setup, and programming
  1. Perform the «Diagnostic System Check - Vehicle»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
  3. «Diagnostic Procedure Instructions»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.
CircuitShort to GroundOpen/High ResistanceShort to VoltageSignal Performance
Courtesy Lamps Switch On SignalB2615 00B2615 00B2615 00
Courtesy Lamp Defeat Signal111
Courtesy Lamps Defeat Switch Ground1
Rear Compartment Courtesy Lamp ControlB2560 02B2560 04B2560 01
Rear Compartment Courtesy Lamp Ground4
Dome/Courtesy Lamp ControlB2615 02B2615 043
Dome/Courtesy Lamp Ground2
1. Dome/Courtesy Lamp Defeat Switch Malfunction 2. Dome/Courtesy Lamp Inoperable 3. Dome/Courtesy Lamp Always ON 4. Rear Compartment Courtesy Lamp Inoperable

Battery voltage for the courtesy lamps is supplied at all times to the body control module (BCM). When the BCM receives a signal to command the courtesy lamps ON, it then applies voltage through the dome/courtesy lamps control circuit to the courtesy lamps.

Schematic Reference

Connector End View Reference

Description and Operation

Electrical Information Reference

  1. «Circuit Testing»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «Testing for Intermittent Conditions and Poor Connections»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
  4. «Wiring Repairs»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

  1. Ignition ON, observe the scan tool Door Ajar Switch parameter while opening and closing each vehicle door. The parameter should change between Inactive and Active. If the parameter does not change between the selected states, refer to «Door Ajar Indicator Malfunction»(/buick/regal/v-2009-2013/remont/door-locks-anti-theft-systems/#power-door-lock-system-and-release-systems)
  2. Observe the scan tool Rear Closure Ajar Switch parameter while opening and closing the trunk. The parameter should change between Active and Inactive. If the parameter does not change between the selected states, refer to «Trunk Ajar Indicator Malfunction»(/buick/regal/v-2009-2013/remont/door-locks-anti-theft-systems/#power-door-lock-system-and-release-systems)
  3. Observe the scan tool Interior/Courtesy Lighting Master Switch parameter while cycling the E37F courtesy lamp defeat switch ON and OFF. The parameter should change between Cancel, Door and ON. If the specified parameter does not change as commanded, refer to Dome Lamp Switch Malfunction in «Circuit/System Testing»(/buick/regal/v-2009-2013/remont/exterior-lights/#lighting-system) .
  4. Courtesy lamp defeat switch OFF, observe the scan tool Dome Lamp Switch parameter while turning the dome lamp switch ON and OFF. The parameter should change between Active and Inactive. If the courtesy lamps do not turn ON and OFF when commanded, refer to Dome Lamp Switch Malfunction in «Circuit/System Testing»(/buick/regal/v-2009-2013/remont/exterior-lights/#lighting-system) .
  5. Command the Courtesy Lamps ON and OFF with a scan tool. The courtesy lamps should turn ON and OFF when changing between the commanded states. If the courtesy lamps do not turn ON and OFF when commanded, refer to Courtesy Lamp Malfunction in «Circuit/System Testing»(/buick/regal/v-2009-2013/remont/exterior-lights/#lighting-system) .
  6. Turn the individual reading lamps ON and OFF with their respective switches. The reading lamps should turn ON and OFF when changing between the selected states. If any reading lamp does not turn ON and OFF when selected, refer to Reading Lamp Malfunction in «Circuit/System Testing»(/buick/regal/v-2009-2013/remont/exterior-lights/#lighting-system) .
  7. Turn the A3 sunshade lamps ON and OFF with their respective switches. The sunshade lamps should turn ON and OFF when changing between the selected states. If any reading lamp does not turn ON and OFF when selected, refer to Sunshade Illumination Malfunction in «Circuit/System Testing»(/buick/regal/v-2009-2013/remont/exterior-lights/#lighting-system) .
  8. Turn the E8S rear compartment courtesy lamp ON and OFF by opening and closing the trunk. The rear compartment courtesy lamp should turn ON and OFF when changing between the selected states. If the rear compartment courtesy lamp does not turn ON and OFF when selected, refer to Rear Compartment Courtesy Lamp Malfunction in «Circuit/System Testing»(/buick/regal/v-2009-2013/remont/exterior-lights/#lighting-system) .
  9. Turn the E27 instrument panel compartment lamp ON and OFF by turning the instrument panel compartment lamp switch ON and OFF. The instrument panel compartment lamp should turn ON and OFF when changing between the selected states. If the instrument panel compartment lamp does not turn ON and OFF when selected, refer to Instrument Panel Compartment Lamp Malfunction in «Circuit/System Testing»(/buick/regal/v-2009-2013/remont/exterior-lights/#lighting-system) .

Dome Lamp Switch Malfunction

  1. Ignition OFF, disconnect the harness connector at the E37F dome/reading lamps - front.
  2. Scan tool OFF, doors CLOSED, interior lamps OFF, test for less than 20 ohms between the ground circuit terminal 6 and ground. If greater than the specified range, test the ground circuit for an open/high resistance.
  3. Ignition ON, verify the scan tool Interior/Courtesy Lighting Master Switch parameter is Door. If the parameter is Cancel, test terminal 4 for short to ground. If the parameter is ON, test terminal 5 for short to ground.
  4. Connect a 3 A fused jumper wire between the signal circuit terminal 4 and ground. Verify the scan tool Interior/Courtesy Lighting Master Switch parameter is Door. If not the specified value, test the signal circuit for a short to B+ or an open/high resistance. If the circuit tests normal, replace the BCM.
  5. Connect a 3 A fused jumper wire between the signal circuit terminal 5 and ground. Verify the scan tool Dome Lamp Switch parameter is Door. If not the specified value, test the signal circuit for a short to B+ or an open/high resistance. If the circuit tests normal, replace the K9 BCM.
  6. If all circuits test normal, replace the E37F dome/reading lamps - front.

Courtesy Lamp Malfunction

  1. Disconnect the harness connector at the appropriate courtesy lamp.
  2. Ignition OFF, scan tool OFF, doors CLOSED, interior lamps OFF, test for less than 5 ohms between the ground circuit terminal listed below and ground: E37 dome/reading lamp - terminal 6 A3 sunshade lamp - terminal B E8 instrument panel courtesy lamp - terminal 2 If greater than the specified range, test the ground circuit for an open/high resistance.
  3. Connect a test lamp between the control circuit terminal listed below and ground: E37 dome/reading lamp - terminal 1 A3 Sunshade lamp - terminal A E8 instrument panel courtesy lamp - terminal 1
  4. Command the Courtesy Lamps ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states. If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the K9 BCM. If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the K9 BCM.
  5. If all circuits test normal, replace the courtesy lamp.

Reading Lamp Malfunction

  1. Disconnect the harness connector at the appropriate E37 dome/reading lamp.
  2. Ignition OFF, scan tool OFF, doors CLOSED, interior lamps OFF, test for less than 5 ohms between the ground circuit terminal 6 and ground. If greater than the specified range, test the ground circuit for an open/high resistance.
  3. Ignition ON, verify that a test lamp illuminates between the control circuit terminal 1 and ground. If the test lamp does not illuminate, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the K9 BCM.
  4. If all circuits test normal, replace the E37 dome/reading lamp.

Sunshade Illumination Malfunction

  1. Ignition OFF, disconnect the harness connector at the appropriate A3 sunshade.
  2. Ignition OFF, scan tool OFF, doors CLOSED, interior lamps OFF, test for less than 5 ohms between the ground circuit terminal B and ground. If greater than the specified range, test the ground circuit for an open/high resistance.
  3. Ignition ON, verify that a test lamp illuminates between the control circuit terminal A and ground. If the test lamp does not illuminate, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the K9 BCM.
  4. If all circuits test normal, replace the A3 sunshade.

Rear Compartment Courtesy Lamp Malfunction

  1. Ignition OFF, disconnect the harness connector at the E8S rear compartment courtesy lamp.
  2. Open the trunk.
  3. Verify that a test lamp illuminates between B+ and the ground circuit terminal 2. If the test lamp does not illuminate, test the ground circuit for short to voltage or an open/high resistance.
  4. Ignition ON, verify that a test lamp illuminates between the control circuit terminal 1 and ground. If the test lamp does not illuminate, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the K9 BCM.
  5. If all circuits test normal, replace the E8S rear compartment courtesy lamp.

Instrument Panel Compartment Lamp Malfunction

  1. Ignition OFF, disconnect the harness connector at the E27 instrument panel compartment lamp.
  2. Open the instrument panel compartment.
  3. Ignition OFF, verify that a test lamp illuminates between B+ and the ground circuit terminal 2. If the test lamp does not illuminate, test the ground circuit for an open/high resistance.
  4. Ignition ON, verify that a test lamp illuminates between the control circuit terminal 1 and ground. If the test lamp does not illuminate, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the K9 BCM.
  5. If all circuits test normal, replace the E27 instrument panel compartment lamp.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

  1. Refer to the appropriate replacement procedure for the lighting component that requires replacement.
  2. «Control Module References»(/buick/regal/v-2009-2013/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for BCM replacement, programming and setup
  1. Perform the «Diagnostic System Check - Vehicle»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
  3. «Diagnostic Procedure Instructions»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.
CircuitShort to GroundOpen/High ResistanceShort to VoltageSignal Performance
Lighting Control Switch ReferenceB1405 03, B1529 03, B257B 03B257B 031
Lighting Control Switch SignalB257B 03B257B 031
Fog Lamp Relay Control232
Front Fog Lamp Control332
Front Fog Lamp Ground3
1. Front Fog Lamp Switch Malfunction 2. Front Fog Lamp Always ON 3. Front Fog Lamp Always OFF

The front fog lamp relay is supplied with battery voltage at all times. The front fog lamp switch signal circuit is grounded momentarily by pressing the front fog lamp switch. The body control module (BCM) energizes the front fog lamp relay by applying ground to the front fog lamp relay control circuit. When the front fog lamp relay is energized, the relay switch contacts close and battery voltage is applied through the front fog lamp fuse to the front fog lamp supply voltage circuit which illuminates the front fog lamps. With the front fog lamp switch activated, the BCM sends a message via serial data to the instrument cluster requesting the instrument cluster to illuminate the front fog indicator.

Schematic Reference

Connector End View Reference

Description and Operation

Electrical Information Reference

  1. «Circuit Testing»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «Testing for Intermittent Conditions and Poor Connections»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
  4. «Wiring Repairs»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

  1. Ignition ON, observe the scan tool Front Fog Lamps Switch parameter while turning the front fog lamps switch ON and OFF. The parameter should change between Active and Inactive. If the parameter does not change between the commanded states, refer to Front Fog Lamp Switch Malfunction in «Circuit/System Testing»(/buick/regal/v-2009-2013/remont/exterior-lights/#lighting-system) .
  2. Ignition ON, turn the front fog lamps ON and OFF using the front fog lamps switch. The front fog lamps should turn ON and OFF when changing between the commanded states. If the front fog lamps do not turn ON and OFF, refer to Front Fog Lamp Malfunction in «Circuit/System Testing»(/buick/regal/v-2009-2013/remont/exterior-lights/#lighting-system) .
  3. Command the All Indicators ON and OFF with a scan tool. The front fog lamps indicator should turn ON and OFF when changing between the commanded states. If the front fog lamps indicator illuminates during the test, replace the K9 BCM. If the front fog lamps indicator does not illuminate during the test or remains illuminated at all times, replace the P16 instrument cluster.

Front Fog Lamp Switch Malfunction

  1. Ignition OFF, disconnect the harness connector at the S30 headlamp switch.
  2. Test for less than 30 ohms between the ground circuit terminal 6 and ground. If greater than the specified range, test the ground circuit for an open/high resistance.
  3. Ignition ON, verify that a test lamp illuminates between the B+ circuit terminal 1 and ground. If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the K9 BCM.
  4. Ignition ON, test for less than 0.3 V between signal circuit terminal 12 and ground. If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the K9 BCM.
  5. Install a 3 A fused jumper wire between the signal circuit terminal 12 and the B+ circuit terminal 1. The interior backlighting should be dimmed. If the interior backlighting is not dimmed, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the K9 BCM.
  6. If all circuits test normal, test or replace the S30 headlamp switch.

Front Fog Lamps Malfunction

  1. Ignition OFF, disconnect the X2 harness connector at the X50A underhood fuse block.
  2. Connect a test lamp between the control circuit terminal 19 and B+.
  3. Command the Front Fog Lamps ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states. If the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the K9 BCM. If the test lamp is always OFF, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the K9 BCM.
  4. Ignition OFF, connect the X2 harness connector at the X50A underhood fuse block. Disconnect the harness connector at the E29 fog lamp-front.
  5. Test for less than 30 ohms between the ground circuit terminal 2 and ground. If greater than the specified range, test the ground circuit for an open/high resistance.
  6. Connect a test lamp between the control circuit terminal 1 and ground.
  7. Ignition ON, command the Fog Lamps ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states. If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the X50A underhood fuse block. If the test lamp is always OFF and the circuit fuse is good, test the control circuit for an open/high resistance. If the circuit tests normal, test or replace the X50A underhood fuse block. If the test lamp is always OFF and the circuit fuse is open, test the control circuit for a short to ground. If the circuit tests normal, test or replace the E29 fog lamp-front.
  8. If all circuits test normal, test or replace the E29 fog lamp-front.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

  1. «Underhood Electrical Center or Junction Block Replacement»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-repair-instructions)
  2. «Front Fog Lamp Bulb Replacement»(/buick/regal/v-2009-2013/remont/exterior-lights/#lighting-system)
  3. «Front Fog Lamp Replacement»(/buick/regal/v-2009-2013/remont/exterior-lights/#lighting-system)
  4. «Headlamp Switch Replacement»(/buick/regal/v-2009-2013/remont/exterior-lights/#lighting-system)
  5. «Control Module References»(/buick/regal/v-2009-2013/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for BCM or instrument panel cluster replacement, programming and setup
  1. Perform the «Diagnostic System Check - Vehicle»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
  3. «Diagnostic Procedure Instructions»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.
CircuitShort to GroundOpen/High ResistanceShort to VoltageSignal Performance
Hazard Switch SignalB3596 00, 211
Hazard Switch Ground1
1. Hazard Lamps Inoperative 2. Hazard Lamps Always ON

The hazard flashers may be activated in any power mode. The hazard switch is permanently grounded. When the hazard switch is placed in the ON position, ground is applied through the hazard switch signal circuit to the body control module (BCM). The BCM supplies battery voltage to all turn signal lamps in an ON and OFF duty cycle. When the hazard switch is activated, the BCM sends a serial data message to the instrument cluster requesting both turn signal indicators to be cycled ON and OFF.

Schematic Reference

Connector End View Reference

Description and Operation

Electrical Information Reference

  1. «Circuit Testing»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «Testing for Intermittent Conditions and Poor Connections»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
  4. «Wiring Repairs»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

  1. Ignition ON, observe the scan tool Hazard Lamps Switch parameter while applying and releasing the hazard switch. The reading should change between Active and Inactive. If the parameter does not change between the commanded states, refer to Circuit/System Testing in «Circuit/System Testing»(/buick/regal/v-2009-2013/remont/exterior-lights/#lighting-system) .
  2. Observe the right and left turn signal lamps while applying and releasing the hazard lamp switch. The right and left turn signal lamps should flash ON and OFF while the hazard lamp switch is ON and remain OFF when the hazard lamp switch is OFF. If the turn signal lamps do not cycle between the selected states, refer to «Turn Signal Lamps and/or Indicators Malfunction»(/buick/regal/v-2009-2013/remont/exterior-lights/#lighting-system) .
  3. Command the All Indicators Test ON and OFF with a scan tool. The left and right turn signal indicators should turn ON and OFF when changing between the commanded states. If the left and right turn signal indicators illuminate during the test, replace the K9 BCM. If the left and right turn signal indicators do not illuminate during the test or remain illuminated at all times, replace the P16 instrument panel cluster.
  1. Ignition OFF, disconnect the harness connector at the S48C multifunction switch 1-instrument panel.
  2. Ignition OFF and all vehicle systems OFF. It may take up to 2 minutes for all vehicle systems to power down. Test for less than 10 ohms between the ground circuit terminal 7 and ground. If greater than the specified range, test the ground circuit for an open/high resistance.
  3. Ignition ON, verify the scan tool Hazard Lamps Switch parameter is Inactive. If not the specified value, test the signal circuit terminal 10 for a short to ground. If the circuits tests normal, replace the K9 BCM.
  4. Install a 3 A fused jumper wire between the signal circuit terminal 10 and the ground circuit terminal 7. Verify the scan tool Hazard Lamps Switch parameter is Active. If not the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the K9 BCM.
  5. If all circuits test normal, test or replace the S48C multifunction switch 1-instrument panel.

Perform the Diagnostic Repair Verification after completing the repair.

  1. «Hazard Warning Switch Replacement»(/buick/regal/v-2009-2013/remont/exterior-lights/#lighting-system)
  2. «Control Module References»(/buick/regal/v-2009-2013/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for BCM or instrument cluster replacement, programming and setup
  1. Perform the «Diagnostic System Check - Vehicle»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
  3. «Diagnostic Procedure Instructions»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.
CircuitShort to GroundOpen/High ResistanceShort to VoltageSignal Performance
Low Beam Headlamp Supply Voltage113
High Beam Headlamp Supply Voltage224
Headlamp Ground1, 2
Headlamp High Beam Relay Control421
Headlamp Switch Headlamps OFF SignalB257A 0066*
Headlamp Switch Headlamps On SignalB257A 0011*
Headlamp Switch Ground3
Flash to Pass Switch Signal455
High Beam Signal422
Turn Signal/Multifunction Switch Ground2, 5
* Internal damage to the headlamp switch may occur if shorted to B+ 1. Low Beam Headlamps Inoperative 2. High Beam Headlamps Inoperative 3. Low Beam Headlamps always ON 4. High Beam Headlamps always ON 5. Flash to Pass Inoperative 6. Headlamp Defeat Inoperative

The vehicle headlamps are controlled by the body control module (BCM) based on inputs from the headlamp switch and the turn signal/multifunction switch. The headlamp switch has four positions: OFF, AUTOMATIC LIGHT, PARKING LIGHT, and LOW BEAM. The default headlamp switch position is AUTOMATIC LIGHT, in which the BCM uses the ambient light sensor to determine when headlamps are needed. The OFF portion of the headlamp switch is a momentary switch which overrides the automatic headlamp and will turn OFF the vehicle headlamps. When in the OFF position, the headlamp switch grounds the headlamp switch headlamps OFF signal circuit, prompting the BCM to turn OFF the headlamps. The Park position of the headlamp switch will only illuminate the vehicle parking lamps. The LOW BEAM position of the headlamp switch will illuminate both the parking lamps, as well has the headlamps. With the headlamp switch in the LOW BEAM position, the headlamp switch headlamps on signal circuit is grounded, prompting the BCM to turn on the headlamps, regardless of other factors such as ambient light.

The headlamp high beams are controlled through the flash to pass switch and the high beam select, both located in the turn signal/multifunction switch. The flash to pass switch is a momentary type switch, designed to illuminate the high beams as long as the switch is held. With the switch closed, the flash to pass switch signal circuit is grounded, prompting the BCM to turn on the high beam lamps. The high beam select switch allows the operator to select between full time high or low beam operation. Unlike the flash to pass switch, it is not a momentary switch. When the high beam select switch is in the high beam position, the high beam select switch signal circuit is grounded. This prompts the BCM to turn on the high beam lamps.

The BCM controls the headlamps based on the inputs explained above. When a low beam request is received, the BCM supplies a B+ voltage to the headlamp low beams. This B+ voltage then illuminates the low beam headlamps. When a high beam request is received, the BCM grounds the headlamp high beam relay control circuit. This energizes the coil in the headlamp high beam relay, causing the relay switch to close. This then applies B+ to both high beam headlamps through the left high beam and right high beam fuses, illuminating the high beam headlamps.

Schematic Reference

Connector End View Reference

Description and Operation

Electrical Information Reference

  1. «Circuit Testing»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «Testing for Intermittent Conditions and Poor Connections»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
  4. «Wiring Repairs»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

  1. Ignition ON, observe the scan tool Headlamps On Switch parameter while turning the headlamp switch ON and OFF. The reading should toggle between Active and Inactive. If the reading does not change between the commanded states, refer to Headlamp Switch Malfunction in «Circuit/System Testing»(/buick/regal/v-2009-2013/remont/exterior-lights/#lighting-system) .
  2. Observe the scan tool Automatic Headlamps Disable Switch parameter while applying and releasing the automatic lamp control disable switch. The reading should toggle between Active and Inactive. If the reading does not change between the commanded states, refer to Headlamp Switch Malfunction in «Circuit/System Testing»(/buick/regal/v-2009-2013/remont/exterior-lights/#lighting-system) .
  3. Observe the scan tool Headlamps Flash Switch parameter while applying and releasing the flash to pass switch. The reading should toggle between Active and Inactive. If the reading does not change between the commanded states, refer to Turn Signal/Multifunction Switch Malfunction in «Circuit/System Testing»(/buick/regal/v-2009-2013/remont/exterior-lights/#lighting-system) .
  4. Observe the scan tool High Beam Select Switch parameter while applying and releasing the high beam select switch. The reading should toggle between Active and Inactive. If the reading does not change between the commanded states, refer to Turn Signal/Multifunction Switch Malfunction in «Circuit/System Testing»(/buick/regal/v-2009-2013/remont/exterior-lights/#lighting-system) .
  5. Command the Headlamp Low Beam Command ON and OFF with a scan tool. The low beam headlamps should turn ON and OFF when changing between the commanded states. If the low beam headlamps do not turn ON and OFF when changing between the commanded states, refer to Headlamps Malfunction - Low Beam in «Circuit/System Testing»(/buick/regal/v-2009-2013/remont/exterior-lights/#lighting-system) .
  6. Turn the high beam headlamps ON and OFF with the turn signal/multifunction switch. The high beam headlamps should turn ON and OFF when changing between the selected states. If the high beam headlamps do not turn ON and OFF when changing between the selected states, refer to Headlamps Malfunction - High Beam in «Circuit/System Testing»(/buick/regal/v-2009-2013/remont/exterior-lights/#lighting-system) .
  7. Command the All Indicators Test ON and OFF with a scan tool. The high beam indicator should turn ON and OFF when changing between the commanded states. If the high beam indicator illuminates during the test, replace the K9 BCM. If the high beam indicator does not illuminate during the test or remains illuminated at all times, replace the P16 instrument cluster.

Headlamp Switch Malfunction

  1. Ignition OFF, disconnect the harness connector at the S30 headlamp switch.
  2. Ignition OFF, test for less than 30 ohms between the ground circuit terminal 6 and ground. If greater than the specified range, test the ground circuit for an open/high resistance.
  3. Ignition ON, verify the scan tool Headlamps On Switch parameter is Inactive. If not the specified value, test the signal circuit terminal 4 for short to ground. If the circuit tests normal, replace the K9 BCM.
  4. Verify the scan tool Automatic Headlamps Disable Switch parameter is Inactive. If not the specified value, test the signal circuit terminal 5 for short to ground. If the circuit tests normal, replace the K9 BCM.
  5. Install a 3 A fused jumper wire between the signal circuit terminal 4 and ground. Verify the scan tool Headlamps On Switch parameter is Active. If not the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the K9 BCM.
  6. Install a 3 A fused jumper wire between the signal circuit terminal 5 and ground. Verify the scan tool Automatic Headlamps Disable Switch parameter is Active. If not the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the K9 BCM.
  7. If all circuits test normal, test or replace the S30 headlamp switch.

Turn Signal/Multifunction Switch Malfunction

  1. Ignition OFF, disconnect the harness connector at the S78 turn signal/multifunction switch.
  2. Ignition OFF, test for less than 5.0 ohms between the ground circuit terminal 3 and ground. If greater than the specified range, test the ground circuit for an open/high resistance.
  3. Ignition ON, verify the scan tool Headlamps Flash Switch parameter is Inactive. If not the specified value, test the signal circuit terminal 4 for a short to ground. If the circuit tests normal, replace the K9 BCM.
  4. Verify the scan tool High Beam Select Switch parameter is Inactive. If not the specified value, test the signal circuit terminal 2 for a short to ground. If the circuit tests normal, replace the K9 BCM.
  5. Install a 3 A fused jumper wire between the signal circuit terminal 4 and ground. Verify the scan tool Headlamps Flash Switch parameter is Active. If not the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the K9 BCM.
  6. Install a 3 A fused jumper wire between the signal circuit terminal 2 and ground. Verify the scan tool High Beam Select Switch parameter is Active. If not the specified value, test the signal circuit for a short to voltage or and open/high resistance. If the circuit tests normal, replace the K9 BCM.
  7. If all circuits test normal, test or replace the S78 turn signal/multifunction switch.

Headlamps Malfunction - Low Beam

  1. Ignition OFF, disconnect the harness connector at the appropriate E13 headlamp.
  2. Ignition OFF, scan tool disconnected, exterior lamps OFF, test for less than 5.0 ohms between the ground circuit terminal 1 and ground. If greater than the specified range, test the ground circuit for an open/high resistance.
  3. Connect a test lamp between the control circuit terminal 3 and ground.
  4. Command the appropriate Headlamp Low Beam ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states. If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the K9 BCM. If the test lamp is always OFF, test the control circuit for a short to ground or open/high resistance. If the circuit tests normal, replace the K9 BCM.
  5. If all circuits test normal, test or replace the E13 headlamp.

High Beam Headlamps Inoperative

  1. Ignition OFF, disconnect the harness connector at the appropriate E4 Headlamp - High Beam.
  2. Test for less than 30 ohms between the ground circuit terminal 2 and ground. If greater than the specified range, test the ground circuit for an open/high resistance.
  3. Connect a test lamp between the control circuit terminal 1 and ground.
  4. Ignition ON, command the High Beams ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states. If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the X50A underhood fuse block. If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the X50A underhood fuse block.
  5. If all circuits test normal, test or replace the bulb or the E4 Headlamp - High Beam

High Beam Command Malfunction

  1. Ignition OFF, disconnect the X2 harness connector at the X50A underhood fuse block.
  2. Connect a test lamp between the control circuit terminal 58 and B+.
  3. Ignition ON, command the High Beam Lamps ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states. If the test lamp is always OFF, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the K9 BCM. If the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the K9 BCM
  4. Ignition OFF, connect the X2 harness connector and disconnect the X1 harness connector at the X50A underhood fuse block.
  5. Ignition ON, verify that a test lamp does not illuminate between the control circuit terminals listed below and ground. Control terminal 13 Control terminal 14 If the test lamp is always ON, test the control circuit for a short to voltage.
  6. If all circuits test normal, replace the X50A underhood fuse block.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

  1. «Relay Replacement (Within an Electrical Center)»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-repair-instructions) , «Relay Replacement (Attached to Wire Harness)»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-repair-instructions)
  2. «Headlamp Switch Replacement»(/buick/regal/v-2009-2013/remont/exterior-lights/#lighting-system)
  3. «Turn Signal Multifunction Switch Replacement»(/buick/regal/v-2009-2013/remont/steering-column-switches/#steering-wheel-and-steering-column)
  4. «Headlamp Replacement»(/buick/regal/v-2009-2013/remont/exterior-lights/#lighting-system)
  5. «Headlamp Bulb Replacement (TT4 Low Beam)»(/buick/regal/v-2009-2013/remont/exterior-lights/#lighting-system) , «Headlamp Bulb Replacement (TT4 High Beam)»(/buick/regal/v-2009-2013/remont/exterior-lights/#lighting-system)
  6. «Control Module References»(/buick/regal/v-2009-2013/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for BCM or instrument cluster replacement, programming and setup
  1. Perform the «Diagnostic System Check - Vehicle»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
  3. «Diagnostic Procedure Instructions»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.
CircuitShort to GroundOpen/High ResistanceShort to VoltageSignal Performance
Interior Accent Light ControlB2652 0221
Interior Accent Light Ground2
1. Interior Accent Light At Full Intensity And Does Not Dim 2. Interior Accent Light Do Not Illuminate

The body control module (BCM) uses the ambient light sensor to determine which brightness of the accent light is needed. The BCM applies a pulse width modulated (PWM) voltage through the accent LED control circuit. Depending on the specified lighting requirements, the BCM has three different accent lighting settings

  1. Daylight Conditions (70%)
  2. Night Conditions (40%)
  3. Welcome Light Illumination (100%)

Schematic Reference

Connector End View Reference

Description and Operation

Electrical Information Reference

  1. «Circuit Testing»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «Testing for Intermittent Conditions and Poor Connections»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
  4. «Wiring Repairs»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

  1. Observe the driver information center while opening and closing each vehicle door and the liftgate. The driver information center should display the door ajar/liftgate ajar message only when the door/liftgate is open. If the driver information center displays the door ajar/liftgate ajar message when a door or the liftgate is closed, refer to «Door Ajar Indicator Malfunction»(/buick/regal/v-2009-2013/remont/door-locks-anti-theft-systems/#power-door-lock-system-and-release-systems) .
  2. When opening the driver door the accent lighting should turn ON. When closing the driver door and locking the vehicle, the accent lighting should turn OFF after 5 seconds. If the backlighting does not go ON and OFF, refer to «Circuit/System Testing»(/buick/regal/v-2009-2013/remont/exterior-lights/#lighting-system) .
  1. Ignition OFF, disconnect the harness connector at any component with inoperative backlighting.
  2. Ignition OFF, scan tool disconnected, interior lamps OFF, doors CLOSED, test for less than 5 ohms between the ground circuit and ground. If greater than the specified value, test the ground circuit for an open/high resistance.
  3. Connect a test lamp between the control circuit and ground.
  4. Command the Incandescent Dimming ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states. If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the K9 BCM. If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the K9 BCM.
  5. If all circuits test normal, test or replace the component with the inoperative backlighting.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

  1. Refer to the appropriate replacement procedure for the component causing the condition.
  2. «Control Module References»(/buick/regal/v-2009-2013/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for BCM replacement, programming and setup
  1. Perform the «Diagnostic System Check - Vehicle»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
  3. «Diagnostic Procedure Instructions»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.
CircuitShort to GroundOpen/High ResistanceShort to VoltageSignal Performance
Headlamp and Panel Dimmer Switch B+B257B 03, B1405 03, B1529 03B257B 03
Headlamp and Panel Dimmer Switch SignalB257B 03B257B 03B257B 07
Interior Backlighting ControlB2610 0221
Interior Backlighting Ground2
1. Interior backlighting at full intensity and cannot be dimmed 2. Interior backlighting does not illuminate

The body control module (BCM) supplies a reference voltage to the backlight dimmer switch, which is part of the headlamp switch. When the backlight dimmer switch is placed in a desired brightness position, reference voltage is applied through the backlight dimmer switch to the BCM. The BCM interprets this voltage signal, then applies a pulse width modulated (PWM) voltage to the LED dimming supply circuit to all related interior lamps, illuminating them to the desired level of brightness.

Schematic Reference

Connector End View Reference

Description and Operation

Electrical Information Reference

  1. «Circuit Testing»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «Testing for Intermittent Conditions and Poor Connections»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
  4. «Wiring Repairs»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

  1. Ignition ON, observe the scan tool Incandescent Dimming Duty Cycle Command parameter while operating the dimmer switch from low to high. The parameter should change from a high percentage to a low percentage when the dimmer switch is moved up and down. If the parameter does not change between the selected states, refer to Dimmer Switch Malfunction in «Circuit/System Testing»(/buick/regal/v-2009-2013/remont/exterior-lights/#lighting-system) .
  2. Command the LED Backlight Dimming ON and OFF with a scan tool. The LED backlighting components should turn ON and OFF when changing between the commanded states. If the LED backlighting components do not change between the commanded states, refer to Interior Backlighting Malfunction «Circuit/System Testing»(/buick/regal/v-2009-2013/remont/exterior-lights/#lighting-system) .

Dimmer Switch Malfunction

  1. Ignition OFF, disconnect the harness connector at the S30 headlamp switch.
  2. Ignition ON, verify that a test lamp illuminates between the 12 V reference circuit terminal 1 and ground. If the test lamp does not illuminate, test the 12 V reference circuit for a short to ground or an open/high resistance. If the circuit tests normal and the circuit fuse is open, test the signal circuit terminal 12 for a short to ground.
  3. Verify the scan tool LED Backlight Dimming Command parameter is Inactive. If not the specified value, test the signal circuit terminal 12 for a short to voltage. If the circuit tests normal, replace the K9 BCM.
  4. Install a 3 A fused jumper wire between the signal circuit terminal 12 and the 12 V reference circuit terminal 1. Verify the scan tool LED Backlight Dimming Command parameter is Active. If not the specified value, test the signal circuit for an open/high resistance. If the circuit tests normal, replace the K9 BCM.
  5. If all circuits test normal, test or replace the S30 headlamp switch.

Interior Backlighting Malfunction

  1. Ignition OFF, disconnect the harness connector at the inoperative backlighting component.
  2. Ignition OFF, scan tool disconnected, interior lamps OFF, doors CLOSED, test for less than 5 ohms between the ground circuit and ground. If greater than the specified value, test the ground circuit for an open/high resistance.
  3. Connect a test lamp between the control circuit and ground.
  4. Command the LED Backlight Dimming ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states. If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the K9 BCM. If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the K9 BCM.
  5. If all circuits test normal, replace the inoperative backlighting component.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

  1. «Headlamp Switch Replacement»(/buick/regal/v-2009-2013/remont/exterior-lights/#lighting-system)
  2. Refer to the appropriate replacement procedure for the component causing the condition.
  3. «Control Module References»(/buick/regal/v-2009-2013/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for BCM replacement, programming and setup
  1. Perform the «Diagnostic System Check - Vehicle»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
  3. «Diagnostic Procedure Instructions»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.
CircuitShort to GroundOpen/High ResistanceShort to VoltageSignal Performance
Headlamp Switch Park Lamp Signal1B257A 00B257A 00
Left Park Lamp ControlB2585 02B2585 04B2585 01
Right Park Lamp ControlB3867 02B3867 04B3867 01
License Plate Light ControlB3883 02B3883 042
Park Lamps Ground1
1. Park Lamps Always ON 2. License Plate Lights Always ON

The park lamps, tail lamps and license plate lights are turned ON when the headlamp switch is placed in the PARK or LOW BEAM position or anytime the headlights are requested. When the body control module (BCM) receives a request from the headlamp switch to turn ON the park lamps, the BCM a sends out a voltage on the control circuit. This illuminates the park lamps, tail lamps and license plate lights.

Schematic Reference

Connector End View Reference

Description and Operation

Electrical Information Reference

  1. «Circuit Testing»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «Testing for Intermittent Conditions and Poor Connections»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
  4. «Wiring Repairs»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

  1. Ignition ON, turn the park lamps ON and OFF using the headlamp switch. The scan tool Park Lamps Switch parameter should cycle between Active and Inactive when changing between the selected states. If the parameter does not cycle between the selected states, refer to Park Lamp Switch Malfunction in «Circuit/System Testing»(/buick/regal/v-2009-2013/remont/exterior-lights/#lighting-system) .
  2. Turn the park, license plate and tail lamps ON and OFF using the headlamp switch. The park, license plate and tail lamps should turn ON and OFF when changing between the selected states. If any park, license plate or tail lamp does not turn ON and OFF when changing between the selected states, refer to Park, License, and/or Tail Lamps Malfunction in «Circuit/System Testing»(/buick/regal/v-2009-2013/remont/exterior-lights/#lighting-system) .

Park Lamp Switch Malfunction

  1. Ignition OFF, disconnect the harness connector at the S30 headlamp switch.
  2. Ignition OFF, verify that a test lamp illuminates between B+ and the ground circuit terminal 6. If the test lamp does not illuminate, test the ground circuit for an open/high resistance.
  3. Ignition ON, verify the scan tool Park Lamps Switch parameter is Inactive. If not the specified value, test the signal circuit terminal 3 for a short to ground. If the circuit tests normal, replace the K9 BCM.
  4. Install a 3 A fused jumper wire between the signal circuit terminal 3 and ground. Verify the scan tool Park Lamps Switch parameter is Active. If not the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the K9 BCM.
  5. If all circuits test normal, test or replace the S30 headlamp switch.

Park, License, and/or Tail Lamps Malfunction

  1. Ignition OFF, disconnect the harness connector at the appropriate park, license or tail lamp.
  2. Test for less than 5 ohms between the ground circuit terminal listed below and ground: E13 headlamp - terminal 1 E42 tail lamp assembly - terminal F E7 license plate lamp - terminal 2 If greater than the specified value, test the ground circuit for an open/high resistance.
  3. Connect a test lamp between the control circuit terminal listed below and ground: E13 headlamp - front park lamp - terminal 4 E13 headlamp - side marker lamp - terminal 7 E42 tail lamp assembly - terminal A E7 license plate lamp - terminal 1
  4. Turn the park lamps ON and OFF by using the S30 headlamp switch. The test lamp should turn ON and OFF when changing between the selected states. If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the K9 BCM. If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the K9 BCM.
  5. If all circuits test normal, test or replace the park, license or tail lamp.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

  1. «Headlamp Replacement»(/buick/regal/v-2009-2013/remont/exterior-lights/#lighting-system)
  2. «Front Side Marker Lamp Bulb Replacement»(/buick/regal/v-2009-2013/remont/exterior-lights/#lighting-system)
  3. «Tail Lamp Replacement»(/buick/regal/v-2009-2013/remont/exterior-lights/#lighting-system)
  4. «Tail Lamp Bulb Replacement»(/buick/regal/v-2009-2013/remont/exterior-lights/#lighting-system)
  5. «Rear License Plate Lamp Replacement»(/buick/regal/v-2009-2013/remont/exterior-lights/#lighting-system)
  6. «Rear License Plate Lamp Bulb Replacement»(/buick/regal/v-2009-2013/remont/exterior-lights/#lighting-system)
  7. «Headlamp Switch Replacement»(/buick/regal/v-2009-2013/remont/exterior-lights/#lighting-system)
  8. «Control Module References»(/buick/regal/v-2009-2013/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for BCM replacement, programming and setup
  1. Perform the «Diagnostic System Check - Vehicle»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
  3. «Diagnostic Procedure Instructions»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.
CircuitShort to GroundOpen/High ResistanceShort to VoltageSignal Performance
5 V ReferenceC0277 06C0277 06C0277 07
Brake Lamps SignalC0277 06C0277 06C0277 07C0277 09
Center High Mounted Stop Lamp Control112
Center High Mounted Stop Lamp Ground3
Left Brake Lamps Control112
Right Brake Lamp Control112
Low Reference1
1. Stop Lamps Malfunction 2. Stop Lamps Always ON 3. Stop Lamps Always OFF

The brake pedal position (BPP) sensor is used to sense the action of the driver application of the brake pedal. BPP sensor provides an analog voltage signal that will increase as the brake pedal is applied. The body control module (BCM) provides a low reference signal and a 5 V reference voltage to the BPP sensor. When the variable signal reaches a voltage threshold indicating the brakes have been applied, the BCM will apply battery voltage to the stop lamp control circuit and center high mounted stop lamp control circuit. When the control circuit is energized the stop lamps are illuminated.

Schematic Reference

Connector End View Reference

Description and Operation

Electrical Information Reference

  1. «Circuit Testing»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «Testing for Intermittent Conditions and Poor Connections»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
  4. «Wiring Repairs»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

  1. Ignition ON, observe the scan tool Brake Pedal Switch parameter while applying and releasing the brake pedal. The parameter should change between Active and Inactive when changing between the selected states. If the parameter does not change between the selected states, refer to the Brake Pedal Position Sensor Malfunction in «Circuit/System Testing»(/buick/regal/v-2009-2013/remont/exterior-lights/#lighting-system) .
  2. Observe the left and right stop lamps while pressing and releasing the brake pedal. The stop lamps should turn ON and OFF when changing between the selected states. If the left or right stop lamps do not change between the selected states, refer to the Stop Lamp Malfunctionin «Circuit/System Testing»(/buick/regal/v-2009-2013/remont/exterior-lights/#lighting-system) .
  3. Observe the center high mount stop lamp while pressing and releasing the brake pedal. The center high mount stop lamp should turn ON and OFF when changing between the selected states. If the center high mount stop lamp does not change between the selected states, refer to Center High Mount Stop Lamp Malfunction in «Circuit/System Testing»(/buick/regal/v-2009-2013/remont/exterior-lights/#lighting-system) .

Brake Pedal Position Sensor Malfunction

  1. Ignition OFF, disconnect the harness connector at the B22 brake pedal position sensor.
  2. Ignition OFF, test for less than 5 ohms between the low reference circuit terminal C and ground. If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the K9 BCM.
  3. Ignition ON, test for 4.8-5.2 V between the 5 V reference circuit terminal A and ground. If less than the specified range, test the 5 V reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the K9 BCM. If greater than the specified range, test the 5 V reference circuit for a short to voltage. If the circuit tests normal, replace the K9 BCM.
  4. Verify that the scan tool Brake Pedal Position Sensor parameter is less than 0.3 V. If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the K9 BCM.
  5. Connect a 3 A fused jumper wire between the 5 V reference circuit terminal A and the signal circuit terminal B. Verify that the scan tool Brake Pedal Position Sensor parameter is 4.8-5.2 V. If less than the specified range, test the signal circuit for an open/high resistance. If the circuit tests normal, replace the K9 BCM.
  6. If all circuits test normal, test or replace the B22 brake pedal position sensor.

Stop Lamp Malfunction

  1. Ignition OFF, disconnect the harness connector at the appropriate E5 tail/stop lamp.
  2. Test for less than 5 ohms between the ground circuit terminal 1 and ground. If greater than the specified range, test the ground circuit for an open/high resistance.
  3. Connect a test lamp between the control circuit terminal C and ground.
  4. Ignition ON, press and release the brake pedal. The test lamp should turn ON and OFF when changing between the selected states. If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the K9 BCM. If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the K9 BCM.
  5. If all circuits test normal, test or replace the E5 tail/stop lamp.

Center High Mounted Stop Lamp Malfunction

  1. Ignition OFF, disconnect the harness connector at the E6 center high mounted stop lamp.
  2. Test for less than 5 ohms between the ground circuit terminal 1 and ground. If greater than the specified value, test the ground circuit for an open/high resistance.
  3. Connect a test lamp between the control circuit terminal 2 and ground.
  4. Ignition ON, press and release the brake pedal. The test lamp should turn ON and OFF when changing between the selected states. If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the K9 BCM. If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the K9 BCM.
  5. If all circuits test normal, test or replace the E6 center high mounted stop lamp.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

  1. «Brake Pedal Position Sensor Replacement»(/buick/regal/v-2009-2013/remont/exterior-lights/#lighting-system__brake-pedal-position-sensor-replacement)
  2. «Brake Pedal Position Sensor Calibration»(/buick/regal/v-2009-2013/remont/exterior-lights/#lighting-system__brake-pedal-position-sensor-calibration)
  3. «Tail Lamp Replacement»(/buick/regal/v-2009-2013/remont/exterior-lights/#lighting-system)
  4. «Tail Lamp Bulb Replacement»(/buick/regal/v-2009-2013/remont/exterior-lights/#lighting-system)
  5. «High Mount Stop Lamp Replacement»(/buick/regal/v-2009-2013/remont/exterior-lights/#lighting-system)
  6. «Control Module References»(/buick/regal/v-2009-2013/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for BCM replacement, programming and setup
  1. Perform the «Diagnostic System Check - Vehicle»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
  3. «Diagnostic Procedure Instructions»(/buick/regal/v-2009-2013/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.
CircuitShort to GroundOpen/High ResistanceShort to VoltageSignal Performance
Left Front Turn Signal Lamp ControlB3948 02B3948 04B3948 01
Right Front Turn Signal Lamp ControlB3949 02B3949 04B3949 01
Front Turn Signal Lamp Ground4
Left Rear Turn Signal Lamp ControlB3950 02B3950 04B3950 01
Right Rear Turn Signal Lamp ControlB3951 02B3951 04B3951 01
Tail Lamp Ground5
Left Repeater Lamp ControlB3948 0266
Right Repeater Lamp ControlB3949 0266
Repeater Lamp Ground6
Left Turn Signal Switch Signal222
Right Turn Signal Switch Signal333
Turn Signal/Multifunction Switch Ground1
1. All Turn Signals Lamps and/or Indicators Inoperative 2. Left Turn Signals Malfunction 3. Right Turn Signals Malfunction 4. Front Turn Signal Malfunction 5. Rear Turn Signal Malfunction 6. Repeater Lamp Malfunction

Ground is applied at all times to the turn signal/multifunction switch. The turn signal lamps may only be activated with the ignition switch in the ON or START position. When the turn signal/multifunction switch is placed in either the TURN RIGHT or TURN LEFT position, ground is applied to the body control module (BCM) through either the right turn or left turn signal switch signal circuit. The BCM then applies a pulsating voltage to the front and rear turn signal lamps through there respective voltage supply circuits. When a turn signal request is received by the BCM, a serial data message is sent to the instrument cluster requesting the respective turn signal indicator be pulsed ON and OFF.

Schematic Reference

Connector End View Reference

Description and Operation

Electrical Information Reference

  1. «Circuit Testing»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «Testing for Intermittent Conditions and Poor Connections»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
  4. «Wiring Repairs»(/buick/regal/v-2009-2013/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

  1. Ignition ON, observe the scan tool Right Turn Signal Switch and Left Turn Signal Switch parameters while cycling the turn signal switch between the right and left positions. The parameters should change between Active and Inactive when changing between the selected states. If the parameters do not change between the selected states, refer to Turn Signal Switch Malfunction in «Circuit/System Testing»(/buick/regal/v-2009-2013/remont/exterior-lights/#lighting-system) .
  2. Ignition ON, observe the right and left turn signal lamps while cycling the turn signal switch between the right and left positions. The turn signal lamps turn ON and OFF when changing between the selected states. If the turn signal lamps do not change between the selected states, refer to Turn Signal Lamps Malfunction in «Circuit/System Testing»(/buick/regal/v-2009-2013/remont/exterior-lights/#lighting-system) .
  3. Command the All Indicators Test ON and OFF with a scan tool. The left and right turn signal indicators should turn ON and OFF when changing between the commanded states. If the left and right turn signal indicators illuminate during the test, replace the K9 BCM. If the left and right turn signal indicators do not illuminate during the test or remain illuminated at all times, replace the P16 instrument cluster.

Turn Signal Switch Malfunction

  1. Ignition OFF, disconnect the harness connector at the S78 turn signal/multifunction switch.
  2. Test for less than 5 ohms between the ground circuit terminal 3 and ground. If greater than the specified range, test the ground circuit for an open/high resistance.
  3. Ignition ON, verify the scan tool Left Turn Signal Switch parameter is Inactive. If not the specified value, test the signal circuit terminal 1 for a short to ground. If the circuit tests normal, replace the K9 BCM.
  4. Verify the scan tool Right Turn Signal Switch parameter is Inactive. If not the specified value, test the signal circuit terminal 7 for a short to ground. If the circuit tests normal, replace the K9 BCM.
  5. Install a 3 A fused jumper wire between the signal circuit terminal 1 and ground. Verify the scan tool Left Turn Signal Switch parameter is Active. If not the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the K9 BCM.
  6. Install a 3 A fused jumper wire between the signal circuit terminal 7 and ground. Verify the scan tool Right Turn Signal Switch parameter is Active. If not the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the K9 BCM.
  7. If all circuits test normal, test or replace the S78 turn signal/multifunction switch.

Turn Signal Lamps Malfunction

  1. Ignition OFF, disconnect the harness connector at the appropriate turn signal lamp.
  2. Test for less than 5.0 ohms between the ground circuit terminal listed below and ground. E13 headlamp - terminal 1 E42 tail lamp assembly - terminal F E4 turn signal repeater lamp - terminal 2 If greater than the specified range, test the ground circuit for an open/high resistance.
  3. Connect a test lamp between the control circuit terminal listed below and ground. E13 headlamp - terminal 5 E42 tail lamp assembly - terminal B E4 turn signal repeater lamp - terminal 1
  4. Command the appropriate Turn Signal Lamp ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states. If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the K9 BCM. If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the K9 BCM.
  5. If all circuits test normal, replace the turn signal lamp.

Perform the Diagnostic Repair Verification after completing the repair.

  1. «Turn Signal Multifunction Switch Replacement»(/buick/regal/v-2009-2013/remont/steering-column-switches/#steering-wheel-and-steering-column)
  2. «Headlamp Replacement»(/buick/regal/v-2009-2013/remont/exterior-lights/#lighting-system)
  3. «Front Side Turn Signal Lamp Replacement»(/buick/regal/v-2009-2013/remont/exterior-lights/#lighting-system)
  4. «Front Turn Signal Lamp Bulb Replacement»(/buick/regal/v-2009-2013/remont/exterior-lights/#lighting-system)
  5. «Tail Lamp Replacement»(/buick/regal/v-2009-2013/remont/exterior-lights/#lighting-system)
  6. «Tail Lamp Bulb Replacement»(/buick/regal/v-2009-2013/remont/exterior-lights/#lighting-system)
  7. «Control Module References»(/buick/regal/v-2009-2013/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for BCM or instrument cluster replacement, programming and setup

Brake Pedal Position Sensor Calibration

Note. Brake system does not use a brake switch, stoplight switch or brakelight switch. System uses a Brake Pedal Position Sensor to control these functions.

Calibration Criteria

Note. Do not apply the brake pedal during the brake pedal position sensor calibration procedure. Any movement of the brake pedal during this procedure will cause the calibration procedure to fail. If this occurs, the brake pedal position sensor calibration must be repeated.

Brake pedal position sensor calibration must be performed after the brake pedal position sensor or body control module (BCM) have been serviced. The calibration procedure will set the brake pedal position sensor home value. This value is used by the BCM to determine the action of the driver applying the brake system and to provide this information to the vehicle subsystems via serial data.

Calibration Procedure

  1. Apply the parking brake.
  2. Place the transmission in the PARK position for automatic transmission or NEUTRAL position for manual transmission.
  3. Install a scan tool.
  4. Clear all BCM DTCs before proceeding.
  5. Navigate to the Configuration/Reset Functions menu of the BCM.
  6. Select the Brake Pedal Position Sensor Learn procedure and follow the directions displayed on the screen.

Brake Pedal Position Sensor Replacement

Note. Brake system does not use a brake switch, stoplight switch or brakelight switch. System uses a Brake Pedal Position Sensor to control these functions.

Scheme 15

Scheme 15: Brake Pedal Position Sensor Replacement
Scheme 15: Brake Pedal Position Sensor Replacement
CalloutComponent Name
Preliminary Procedure Remove the instrument panel lower trim panel insulator. Refer to Instrument Panel Lower Trim Panel Insulator Replacement .
1Brake Pedal Position Sensor Bolt CAUTION: Refer to Fastener Caution . Tighten 2 N.m (18 lb in)
2Brake Pedal Position Sensor Procedure Disconnect the electrical connector. Calibrate the brake pedal position sensor. Refer to Brake Pedal Position Sensor Calibration .
CAUTION
Refer to Fastener Caution .

Brake Pedal Position Sensor Replacement

Scheme 16

Scheme 16: Headlamp Switch Replacement
Scheme 16: Headlamp Switch Replacement
CalloutComponent Name
Preliminary Procedure Remove the instrument panel headlamp switch molding. Refer to Headlamp Switch Molding Replacement .
1Headlamp Switch Procedure Disconnect the electrical connector. TIP: Use a flat-bladed plastic trim tool in order to release the retaining clips.

Headlamp Switch Replacement

Scheme 17

Scheme 17: Hazard Warning Switch Replacement
Scheme 17: Hazard Warning Switch Replacement
CalloutComponent Name
Preliminary Procedures Remove the instrument panel upper center trim panel. Refer to Instrument Panel Upper Center Trim Panel Replacement . Disconnect the electrical connector.
1Hazard Warning Switch

Hazard Warning Switch Replacement

Scheme 18

Scheme 18: Headlamp Automatic Control Ambient Light Sensor Replacement
Scheme 18: Headlamp Automatic Control Ambient Light Sensor Replacement
CalloutComponent Name
1Windshield Defroster Nozzle Grille Retainer (Qty: 8) Procedure Disconnect the electrical connections. TIP: Use a flat-bladed plastic trim tool to aid in the removal of the windshield defroster nozzle grille.
2Headlamp Automatic Control Ambient Light Sensor

Headlamp Automatic Control Ambient Light Sensor Replacement

Scheme 19

Scheme 19: Windshield Outside Moisture and Headlamp Automatic Control Ambient Light Sensor Replacement
Scheme 19: Windshield Outside Moisture and Headlamp Automatic Control Ambient Light Sensor Replacement
CalloutComponent Name
Preliminary Procedure Remove the inside rearview mirror mount plate cover. Refer to Inside Rearview Mirror Mount Plate Cover Replacement
1Windshield Outside Moisture and Headlamp Automatic Control Ambient Light Sensor Retainer TIP: Use a small flat-bladed tool to release the locking retainer on the windshield outside moisture and headlamp automatic control ambient light sensor and push the cap upwards.
2Windshield Outside Moisture and Headlamp Automatic Control Ambient Light Sensor

Windshield Outside Moisture and Headlamp Automatic Control Ambient Light Sensor Replacement

Scheme 20

Scheme 20: Reading Lamp Bulb Replacement
Scheme 20: Reading Lamp Bulb Replacement
CalloutComponent Name
1Dome and Reading Lamp Lens TIP: Carefully use a flat-bladed tool, and release the tabs retaining the dome and reading lamp lens to the reading lamp.
2Reading Lamp Bulb CAUTION: Refer to Avoid Touching the Bulb Caution TIP: Service the bulb, as needed.

Reading Lamp Bulb Replacement

Scheme 21

Scheme 21: Reading Lamp Replacement
Scheme 21: Reading Lamp Replacement
CalloutComponent Name
1Reading Lamp Procedure Disconnect the electrical connector. TIP: Carefully use a flat-bladed tool, release the retainer from the reading lamp to the headliner.

Reading Lamp Replacement

Scheme 22

Scheme 22: Dome and Reading Lamp Replacement
Scheme 22: Dome and Reading Lamp Replacement
CalloutComponent Name
Preliminary Procedure Remove the roof console reading lamp bezel. Refer to Roof Console Reading Lamp Bezel Replacement .
1Dome and Reading Lamp TIP: Carefully use a flat-bladed tool to release the retainer from the dome and reading lamp to the roof console.

Dome and Reading Lamp Replacement

Scheme 23

Scheme 23: Dome and Reading Lamp Lens Replacement
Scheme 23: Dome and Reading Lamp Lens Replacement
CalloutComponent Name
Preliminary Procedure Remove the roof console reading lamp bezel. Refer to Roof Console Reading Lamp Bezel Replacement .
1Dome and Reading Lamp Lens TIP: Carefully use a flat-bladed tool to release the retainer from the dome and reading lamp lens to the dome and reading lamp.

Dome and Reading Lamp Lens Replacement

Scheme 24

Scheme 24: Front Side Door Courtesy Lamp Lens Replacement
Scheme 24: Front Side Door Courtesy Lamp Lens Replacement
CalloutComponent Name
1Front Side Door Courtesy Lamp Lens Procedure Release and pull off the front side door courtesy lamp lens. Disconnect the electrical connector. TIP: Carefully use a flat-bladed tool, and release the compartment lamp.

Front Side Door Courtesy Lamp Lens Replacement

Scheme 25

Scheme 25: Front Floor Flood Lamp Replacement
Scheme 25: Front Floor Flood Lamp Replacement
CalloutComponent Name
1Front Floor Flood Lamp Retainer TIP: Use a small flat-bladed tool to pull the right side down out from the front and rear side door sill trim plate opening.
2Front Floor Flood Lamp Procedure Disconnect the front floor flood lamp electrical connector.

Front Floor Flood Lamp Replacement

Scheme 26

Scheme 26: Instrument Panel Multifunction Switch Replacement
Scheme 26: Instrument Panel Multifunction Switch Replacement
CalloutComponent Name
Preliminary Procedure Remove the instrument panel lower center trim panel. Refer to Instrument Panel Lower Center Trim Panel Replacement .
1Instrument Panel Multifunction Switch Procedure Disconnect the electrical connector.

Instrument Panel Multifunction Switch Replacement

Scheme 27

Scheme 27: Instrument Panel Compartment Lamp Replacement
Scheme 27: Instrument Panel Compartment Lamp Replacement
CalloutComponent Name
1Instrument Panel Compartment Lamp Procedure Release and pull off the instrument panel compartment lamp. Disconnect the electrical connector. TIP: Carefully use a flat-bladed tool, and release the compartment lamp from the instrument panel compartment.

Instrument Panel Compartment Lamp Replacement

Scheme 28

Scheme 28: Dome Lamp Bulb Replacement
Scheme 28: Dome Lamp Bulb Replacement
CalloutComponent Name
1Dome and Reading Lamp Lens TIP: Use a small flat-bladed tool to remove the dome and reading lamp lens.
2Dome Lamp Bulb CAUTION: Refer to Avoid Touching the Bulb Caution . TIP: Service the bulb, as needed.
CAUTION
Refer to Avoid Touching the Bulb Caution .

Dome Lamp Bulb Replacement

Scheme 29

Scheme 29: Front Side Door Sill Courtesy Lamp Replacement
Scheme 29: Front Side Door Sill Courtesy Lamp Replacement
CalloutComponent Name
1Front Side Door Sill Courtesy Lamp Retainer TIP: Use a small flat-bladed tool to pull the right side down out from the front side door trim panel opening.
2Front Side Door Sill Courtesy Lamp Procedure Disconnect the front side door sill courtesy lamp electrical connector.

Front Side Door Sill Courtesy Lamp Replacement

Scheme 30

Scheme 30: Headlamp Replacement
Scheme 30: Headlamp Replacement
CalloutComponent Name
Preliminary Procedure Remove the front bumper fascia. Refer to Front Bumper Fascia Replacement . Remove the front bumper fascia support. Refer to Front Bumper Fascia Support Replacement (Right Side) , Front Bumper Fascia Support Replacement (Left Side) .
1Headlamp Screw (Qty: 4) CAUTION: Refer to Fastener Caution . Tighten 2.5 N.m (22 lb in)
2Headlamp Assembly (W/Front Side Marker and Park and Turn Signal Lamp) WARNING: Refer to Halogen Bulb Warning . Procedure Pull the headlamp assembly forward in order to access and disconnect the forward lamp harness electrical connector from the headlamp jumper harness connector. Remove the headlamp bulb accessory covers. Transfer the headlamp bulbs as needed. Aim the headlamps after the headlamps have been re-installed. Refer to Headlamp Aiming .
CAUTION
Refer to Fastener Caution .
WARNING
Refer to Halogen Bulb Warning .

Headlamp Replacement

Scheme 31

Scheme 31: Headlamp Bulb Replacement (TT4 Low Beam)
Scheme 31: Headlamp Bulb Replacement (TT4 Low Beam)
CalloutComponent Name
Preliminary Procedure Open and support the hood assembly.
1Headlamp Bulb Accessory Cover Assembly TIP: Disconnect the electrical connector from the headlamp bulb socket.
2Headlamp Bulb WARNING: Refer to Halogen Bulb Warning . Procedure Rotate the bulb socket a quarter turn counter-clockwise and remove.
WARNING
Refer to Halogen Bulb Warning .

Headlamp Bulb Replacement (TT4 Low Beam)

Scheme 32

Scheme 32: Headlamp Bulb Replacement (TT4 High Beam)
Scheme 32: Headlamp Bulb Replacement (TT4 High Beam)
CalloutComponent Name
Preliminary Procedure Open and support the hood assembly.
1Headlamp Bulb Accessory Cover Assembly TIP: Disconnect the electrical connector from the headlamp bulb socket.
2Headlamp Bulb WARNING: Refer to Halogen Bulb Warning . Procedure Rotate the bulb socket a quarter turn counter-clockwise and remove.
WARNING
Refer to Halogen Bulb Warning .

Headlamp Bulb Replacement (TT4 High Beam)

Scheme 33

Scheme 33: Headlamp Bracket Replacement
Scheme 33: Headlamp Bracket Replacement
CalloutComponent Name
Preliminary Procedure Remove the front bumper fascia. Refer to Front Bumper Fascia Replacement .
1Headlamp Bracket Fastener (Qty: 2) Procedure Hand tighten the fasteners only.
2Headlamp Bracket

Headlamp Bracket Replacement

Aiming Headlamps (Visual Aim)

Note. Some state and local laws specify requirements for headlamp aim. All of these laws must be complied with when performing any headlamp aiming operations.

Headlamp aim should be checked

  1. When a new headlamp capsule is installed.
  2. If service or repairs to the front end area have (or may have) disturbed the headlamps or their mounting.
  3. Suspension components have been replaced or repaired.
  1. The area will consist of a level surface large enough to allow for a vehicle and an additional 7.62 m (25 ft) measured from face of lamps to the front of the aiming screen.
  2. The screen will be 1.52 m (5 ft) high x 3.66 m (12 ft) wide with a matte white surface well shaded from extraneous light, and properly adjusted to the floor on which the vehicle stands. Provisions may be made for moving the screen so it can be aligned parallel with the vehicle.
  3. The screen shall be provided with a fixed vertical centerline, 2 laterally adjustable vertical tapes, and 1 vertically adjustable horizontal tape.
  4. If a regular commercial aiming screen is not available, the screen may consist of a vertical wall having a clear uninterrupted area approximately 1.83 m (6 ft) high and 3.66 m (12 ft) wide. The surface should be finished with a washable non-gloss white paint.
  5. After the aiming screen has been set up in its permanent location, it is necessary to paint a reference line on the floor directly under the lens of the lamps to indicate the proper location of the headlamps when they are being aimed: Distance between headlamps (1) Center line of screen (2) Adjustable vertical pointer (3) Adjustable horizontal tape (4) Diagram of light screen (5) Vertical center line ahead of right headlamp pointer position (6) 7.62 m (25 ft) (7) Car centerline axis (8)

Prior to aiming the headlamps, the following steps must be taken

  1. Remove any snow, ice or mud from the vehicle.
  2. The vehicle must have a full tank of gas.
  3. Stop all other work on the vehicle.
  4. If any service has been performed on the vehicle, make sure that all of the components are back in their original place.
  5. The vehicle must be on a level surface.
  6. The vehicle left tires must be aligned with the reference line extending from the screen with the headlamps aligned with the vertical reference line (2).
  7. Do not load any cargo in the vehicle.
  8. The vehicle must contain 1 person or 72.56 kg (160 lb) on the driver's seat.
  9. Inflate the tires to the proper pressure.
  10. Simulate the vehicle loads if the intended use of the vehicle is for hauling heavy loads or towing a trailer.
  11. Rock the vehicle in order to stabilize the suspension.
  12. Turn ON the headlamps to low beam and observe the left and the top edges of the high intensity zone on the screen. The edges of the high intensity zone should fall within the specifications.

Headlamp Aiming Procedure

  1. Open the hood.
  2. Measure from the floor to the center of the headlamp bulb, some headlamps have an aim dot marked on the headlamp lens.
  3. At the screen, measure from the floor and place the horizontal tape at the measured distance.
  4. Measure from the reference line on the floor to the left headlamp bulb centerline.
  5. At the screen, measure from the reference line and place the vertical tape at the measured distance.
  6. Measure from the reference line on the floor to the right headlamp bulb centerline.
  7. At the screen, measure from the reference line and place the vertical tape at the measured distance.
  8. Turn on the low beam headlamps and block the light from projecting onto the screen from the passenger side headlamp.
  9. Adjust the vertical aim of the headlamps to the specifications required by the state and the local authorities, or as shown in step number 8.
  10. Rotate the headlamp adjuster to change the vertical aim of the headlamp.
  11. Repeat the aiming procedure for the passenger side headlamp while blocking the light from projecting onto the screen from the driver side headlamp.
  12. Close the hood.

Scheme 34

Scheme 34: Headlamp Leveling Front Suspension Height Sensor Replacement
Scheme 34: Headlamp Leveling Front Suspension Height Sensor Replacement
CalloutComponent Name
Preliminary Procedure Raise and support the vehicle. Refer to Lifting and Jacking the Vehicle .
1Headlamp Leveling Front Suspension Height Sensor Fastener (Qty: 2) CAUTION: Refer to Fastener Caution . Tighten 5 N.m (44 lb in)
2Headlamp Leveling Front Suspension Height Sensor Procedure Disconnect the electrical connector. Set up and program the headlamp control module. Refer to Control Module References .
CAUTION
Refer to Fastener Caution .

Headlamp Leveling Front Suspension Height Sensor Replacement

Scheme 35

Scheme 35: Headlamp Leveling Rear Suspension Height Sensor Replacement
Scheme 35: Headlamp Leveling Rear Suspension Height Sensor Replacement
CalloutComponent Name
Preliminary Procedure Raise and support the vehicle. Refer to Lifting and Jacking the Vehicle .
1Headlamp Leveling Rear Suspension Height Sensor Fastener (Qty: 2) CAUTION: Refer to Fastener Caution . Tighten 5 N.m (44 lb in)
2Headlamp Leveling Rear Suspension Height Sensor Procedure Disconnect the electrical connector. Set up and program the headlamp control module. Refer to Control Module References .
CAUTION
Refer to Fastener Caution .

Headlamp Leveling Rear Suspension Height Sensor Replacement

Scheme 36

Scheme 36: Headlamp Control Module Replacement
Scheme 36: Headlamp Control Module Replacement
CalloutComponent Name
Preliminary Procedures Remove the instrument panel lower trim pad cover. Refer to Instrument Panel Lower Trim Panel Insulator Replacement . Remove the body control module. Refer to Body Control Module Replacement (Left Hand Drive) .
1Headlamp Control Module Procedure Disconnect the electrical connectors. Remove the headlamp control module. Set up and program the headlamp control module. Refer to Control Module References .

Headlamp Control Module Replacement

Scheme 37

Scheme 37: Front Fog Lamp Replacement
Scheme 37: Front Fog Lamp Replacement
CalloutComponent Name
Preliminary Procedure Remove the front wheelhouse liner. Refer to Front Wheelhouse Front Liner Replacement . Remove the windshield washer solvent container. Refer to Windshield Washer Solvent Container Replacement .
1Front Fog Lamp Screw (Qty: 2)
2Front Fog Lamp Package Procedure Release the front bumper fascia tab from the fog lamp assembly. Replace the fog lamp as an assembly. Aim the front fog lamps after installation. Refer to Fog Lamp Aiming .

Front Fog Lamp Replacement

Scheme 38

Scheme 38: Front Fog Lamp Bulb Replacement
Scheme 38: Front Fog Lamp Bulb Replacement
CalloutComponent Name
Preliminary Procedures Remove the front wheel house liner on the side the front fog lamp bulb will be serviced. Refer to Front Wheelhouse Front Liner Replacement Disconnect the front fog lamp bulb electrical connector.
1Front Fog Lamp Bulb WARNING: Refer to Halogen Bulb Warning . TIP: Rotate the bulb socket a quarter turn counter-clockwise in order to remove the bulb from the fog lamp projector.
WARNING
Refer to Halogen Bulb Warning .

Front Fog Lamp Bulb Replacement

Adjustment Procedure

Proper road illumination and safety require the fog lamps to be aimed. The front fog lamp aim should be checked when a new front fog lamp assembly is installed, or if any service repairs have been performed to the vehicle which disturb the front fog lamp mounting or the vehicle ride height.

There are no horizontal adjustments for aiming the front fog lamp assemblies on this vehicle.

  1. To ensure accurate vertical front fog lamp aiming, first perform the following steps to prepare the vehicle. Make sure that all the components are in place on the vehicle, the tires are properly inflated, and there is not any mud or snow clinging to the vehicle. Stop all other operations of work on the vehicle. Make sure the fuel level is 1/2 full or more. Jounce the vehicle to settle the suspension. Place the vehicle on a level surface 7.6 m (25 ft) from the target screen. Measure the distance from the floor to the center of the fog lamp (5). Using this measurement, mark the horizontal centerline of the fog lamp (1) on the target screen directly in front of the vehicle. Start the vehicle in order to level the electronic suspension. Turn off the vehicle.
  2. Turn the front fog lamps ON.
  3. Turn the adjusting screw located on the exterior lower outer insert molding assembly, bottom corner of the fog lamp projector and adjust the fog lamp projector aim beam.
  4. Adjust the fog lamp up or down until the top edge of the high intensity zone on the screen is 102 mm (4 in) below the horizontal centerline.
  5. Turn OFF the front fog lamps.

Scheme 39

Scheme 39: Front Side Marker Lamp Bulb Replacement
Scheme 39: Front Side Marker Lamp Bulb Replacement
CalloutComponent Name
Preliminary Procedure Open and support the hood assembly.
1Front Side Marker Lamp Bulb Socket TIP: Rotate the bulb socket counter-clockwise and remove the socket from the headlamp assembly.
2Front Side Marker Lamp Bulb

Front Side Marker Lamp Bulb Replacement

Scheme 40

Scheme 40: Front Side Turn Signal Lamp Replacement
Scheme 40: Front Side Turn Signal Lamp Replacement
CalloutComponent Name
Preliminary Procedures Remove the front wheelhouse rear liner. Refer to Front Wheelhouse Rear Liner Replacement . Disconnect the front side turn signal lamp electrical connector. Squeeze the lamp housing locking retainer and push outward in order to remove the front side turn signal lamp from the fender panel.
1Front Side Turn Signal Lamp TIP: Replace the bulb, as needed.

Front Side Turn Signal Lamp Replacement

Scheme 41

Scheme 41: Front Turn Signal Lamp Bulb Replacement
Scheme 41: Front Turn Signal Lamp Bulb Replacement
CalloutComponent Name
Preliminary Procedure Remove the front turn signal lamp bulb dust cover.
1Front Turn Signal Lamp Bulb Socket Bracket Procedure Unscrew the bulb socket bracket counterclockwise from the headlamp.
2Front Turn Signal Lamp Bulb WARNING: Refer to Halogen Bulb Warning . Procedure Remove the bulb from the lamp socket.
WARNING
Refer to Halogen Bulb Warning .

Front Turn Signal Lamp Bulb Replacement

Scheme 42

Scheme 42: High Mount Stop Lamp Replacement
Scheme 42: High Mount Stop Lamp Replacement
CalloutComponent Name
Preliminary Procedure Remove the rear compartment lid inner panel trim. Refer to Rear Compartment Lid Inner Panel Trim Replacement .
1High Mount Stop Lamp Fastener (Qty: 4) Procedure Press screwdriver onto the screw and unfasten it with about 4-5 rotations still pressing the screwdriver onto the screw. After that, push back the clip. To make sure the screw does not fall into the trunk lid, use a magnetic screwdriver.
2High Mount Stop Lamp Procedure Disconnect the electrical connector at the high mount stop lamp. Use a small flat-bladed tool to release the high mount stop lamp locking retainer starting at the left or right side of the lid compartment. Use new seal. Hand tighten only, no torque required.

High Mount Stop Lamp Replacement

Scheme 43

Scheme 43: Rear License Plate Lamp Replacement
Scheme 43: Rear License Plate Lamp Replacement
CalloutComponent Name
1Rear License Plate Lamp Tap TIP: Using a small flat-bladed tool, pull the right side down out from the rear bumper opening.
2Rear License Plate Lamp Procedure Disconnect the rear license lamp electrical connector.

Rear License Plate Lamp Replacement

Scheme 44

Scheme 44: Rear License Plate Lamp Bulb Replacement
Scheme 44: Rear License Plate Lamp Bulb Replacement
CalloutComponent Name
1Rear License Lamp Retainer TIP: Using a small flat-bladed tool, pull the right side down out from the rear bumper fascia opening.
2Rear License Lamp Socket TIP: Rotate the lamp socket counter clock wise and remove.
3Rear License Lamp Bulb CAUTION: Refer to Avoid Touching the Bulb Caution . TIP: Service the bulb, as needed.
CAUTION
Refer to Avoid Touching the Bulb Caution .

Rear License Plate Lamp Bulb Replacement

Scheme 45

Scheme 45: Tail Lamp Replacement
Scheme 45: Tail Lamp Replacement
CalloutComponent Name
Preliminary Procedure Open the service opening from the rear compartment side trim panel in order to expose the tail lamp fasteners.
1Tail Lamp Fastener (Qty: 4) Procedure Hand tighten the fasteners only.
2Tail Lamp WARNING: Refer to Halogen Bulb Warning . Procedure Lift front of lamp and pull lamp out and rearward. Disconnect the tail lamp electrical connector.
WARNING
Refer to Halogen Bulb Warning .

Tail Lamp Replacement

Scheme 46

Scheme 46: Tail Lamp Bulb Replacement
Scheme 46: Tail Lamp Bulb Replacement
CalloutComponent Name
Preliminary Procedure Open and support the rear compartment lid. Remove either the right or left rear tail lamp assembly. Refer to Tail Lamp Replacement .
1Tail Lamp Bulb Electrical Harness
2Back Up Bulb Socket (Qty: 2) TIP: Rotate the bulb socket counterclockwise and remove from the tail lamp housing.
3Back Up Bulb (Qty: 2) TIP: Pull the bulb from the bulb socket and replace.
4Stop / Tail / Turn Signal Bulb Socket (Qty: 2)
5Stop / Tail / Turn Signal Bulb (Qty: 2)

Tail Lamp Bulb Replacement

Scheme 47

Scheme 47: Rear Compartment Courtesy Lamp Replacement
Scheme 47: Rear Compartment Courtesy Lamp Replacement
CalloutComponent Name
1Rear Compartment Courtesy Lamp Procedure Release and pull off the rear compartment courtesy lamp. Disconnect the electrical connector. TIP: Carefully use a flat-bladed tool, and release the compartment lamp.

Rear Compartment Courtesy Lamp Replacement

Exterior Lamps

The exterior lighting system consist of the following lamps

  1. Headlamps
  2. Daytime running lamps (DRL)
  3. Front fog lamps
  4. Park, tail, license and marker lamps
  5. Turn signal lamps
  6. Hazard warning lamps
  7. Stop lamps
  8. Backup lamps

Low Beam Headlamps

The headlamps consist of 2 interchangeable single filament bulbs on each side of the vehicle which provide high and low beams. The lower bulb in the headlamp is the high beam and the upper bulb is the low beam.

The headlamps may be turned ON in 3 different ways

  1. When the headlamp switch is placed in the ON position, for normal operation.
  2. When the headlamp switch is placed in the AUTOMATIC LIGHT position, for automatic lamp control.
  3. When the headlamp switch is placed in the AUTOMATIC LIGHT position, with the windshield wipers ON in daylight conditions, after a 6 s delay.

The body control module (BCM) controls the headlamps based on the inputs explained above. When a low beam request is received, the BCM applies B+ to both low beam headlamps through the left low beam and right low beam control circuits, illuminating the low beam headlamps.

Automatic Lamp Control

Automatic Light is switched ON as default. It can be switched OFF by turning the headlamp switch to OFF position. It will be switched ON again by doing so again. Automatic Light is only available if a rain sensor or rain/light sensor module in installed in the car. The rain/light sensor module will send the actual ambient light state (day/night) to the BCM. If Automatic Light is enabled, BCM will react on the message received from the rain/light sensor module by switching ON/OFF low beams.

Flash to Pass

When the low beam headlamps are on and the turn signal/multifunction switch is momentarily placed in the flash to pass position, ground is applied to the turn signal/multifunction switch. The turn signal/multifunction switch applies ground to the BCM through the flash to pass switch signal circuit. The BCM then applies ground to the high beam relay control circuit. This energizes the high beam relay, closing the switch side contacts of the high beam relay, applying battery voltage to the left and right high beam fuses. Battery voltage is applied from the high beam fuses through the high beam voltage supply circuit to the high beam headlamp assemblies. This causes the high beam headlamps to illuminate at full brightness momentarily or until the flash to pass switch is released.

Daytime Running Lamps

The DRL bulbs are combined with the park lamps. One filament is for the DRL and one for the park lamps. The DRL will operate when the following conditions are met

  1. Engine is running.
  2. Headlamp switch in AUTOMATIC LIGHT position.
  3. The high and low beam headlamps are OFF.

By turning the headlamp switch in the OFF position the automatic light function and the DRL will be deactivated.

The ambient light sensor is used to monitor outside lighting conditions. The ambient light sensor provides a voltage signal that will vary between 0.2-4.9 V depending on outside lighting conditions. The HVAC control module provides a low reference ground and 5 V reference signals to the ambient light sensor. The BCM monitors the ambient light sensor signal circuit to determine if outside lighting conditions are correct for either DRL or low beam when the headlamp switch is in the AUTOMATIC LIGHT position. In daylight conditions, the BCM will command the DRL ON by applying battery voltage to the left and right DRL lamps. Any function or condition that turns on the headlamps will cancel DRL operation.

Front Fog Lamps

The front fog lamp relay is supplied with battery voltage at all times. The front fog lamp switch signal circuit is grounded momentarily by pressing the front fog lamp switch. The body control module (BCM) energizes the front fog lamp relay by applying ground to the front fog lamp relay control circuit. When the front fog lamp relay is energized, the relay switch contacts close and battery voltage is applied through the front fog lamp fuse to the front fog lamp supply voltage circuit which illuminates the front fog lamps.

Park, Tail, License and Marker Lamps

The rear tail, stop, and turn signal functions are performed by light emitting diodes (LED) in the tail lamp assemblies. The rear side marker lamps uses LEDs and are part of the tail lamp assemblies which wraps around the corner of the vehicle. The front park and side marker lamps are part of the front headlamp assembly. The front side markers uses LEDs the front position lamps use an incandescent bulb. The BCM sends out a PWM signal to illuminate all park, tail, license, and marker lamps as soon when the headlamp switch is placed in the PARK LAMP or HEADLAMP position or anytime the headlights are requested. The park lamps are also turned on with the front fog lamps.

Turn Signal Lamps

Ground is applied at all times to the turn signal/multifunction switch. The turn signal lamps may only be activated with the ignition switch in the ON or START position. When the turn signal/multifunction switch is placed in either the TURN RIGHT or TURN LEFT position, ground is applied to the BCM through either the right turn or left turn signal switch signal circuit. The BCM then applies a pulsating voltage to the front and rear turn signal lamps through their respective voltage supply circuits. When a turn signal request is received by the BCM, a serial data message is sent to the instrument cluster requesting the respective turn signal indicator be pulsed ON and OFF.

Hazard Flasher Lamps

The hazard flashers may be activated in any power mode. The hazard switch is permanently grounded. When the hazard switch is placed in the ON position, ground is applied through the hazard switch signal circuit to the BCM. The BCM supplies battery voltage to all turn signal lamps in an ON and OFF duty cycle. When the hazard switch is activated, the BCM sends a serial data message to the instrument cluster requesting both turn signal indicators to be cycled ON and OFF.

Stop Lamps

Note. Brake system does not use a brake switch, stoplight switch or brakelight switch. System uses a Brake Pedal Position Sensor to control these functions.

The brake pedal position (BPP) sensor is used to sense the action of the driver application of the brake pedal. The BPP sensor provides an analog voltage signal that will increase as the brake pedal is applied. The BCM provides a low reference signal and a 5 V reference voltage to the BPP sensor. When the variable signal reaches a voltage threshold indicating the brakes have been applied, the BCM will apply battery voltage to the stop lamp control circuit and center high mounted stop lamp control circuit. When the control circuit is energized the stop lamps are illuminated.

Backup Lamps

When the transmission is placed in the reverse position, the engine control module (ECM) sends a serial data message to the BCM. The message indicates that the gear selector is in the reverse position. The BCM applies battery voltage to the backup lamps. The backup lamps are permanently grounded. Once the driver moves the gear selector out of the reverse position, a message is sent by the ECM via serial data requesting the BCM to remove battery voltage from the backup lamp control circuit.

Battery Run Down Protection/Inadvertent Power

To provide battery run down protection, the exterior lamps will be deactivated automatically under certain conditions. The BCM monitors the state of the headlamp switch. If the park or headlamp switch is ON when the ignition switch is placed in either the CRANK or RUN position and then placed in the OFF position, the BCM initiates a 10 min timer. At the end of the 10 min, the BCM will turn OFF the control power output to the park and headlamp relay coils, deactivating the exterior lamps. This feature will be cancelled if any power mode other than OFF becomes active. The BCM will disable battery run down protection if any of the following conditions exist. The park or headlamp switch is placed in the ON to OFF position, and back to the ON position during battery run down protection. The BCM determined that the park or headlamp switch was not active when the ignition was turned OFF.

Interior Lamps

The interior lamps consist of 2 groups, those which can dim from the instrument panel cluster lamps dimmer switch and those that can not dim.

Courtesy/Illuminated Entry Lamps

The following lamps may be manually turned ON by placing the interior lamp switch in the ON position, or by opening a door while the switch is in the AUTO position.

  1. The dome lamp
  2. The liftgate lamps
  3. Courtesy lamps

The courtesy lamp supply voltage circuit of the body control module (BCM) supplies battery positive voltage to the dome lamp, the liftgate lamps and courtesy lamps. When any door is opened, the door jamb switch contacts close providing a door open input to the BCM. The BCM then provides a B+ to the interior lamps with the switch in the AUTO position. The interior lamps receive a ground when the switch is in the ON position.

Note. If the liftgate is opened after all the modules go to sleep, the dome light will not come on. The liftgate ajar switch input to the BCM will not wake up the BCM once it has gone to sleep, so the dome light will not come on. Once the BCM gets an input to wake it up, from remote keyless entry or a door handle, the dome light will turn on when the liftgate is opened.

If the driver inadvertently leaves any interior lamp ON, the BCM will turn it OFF after a 20 min time-out.

The courtesy lamps will turn OFF immediately if the ignition switch is turned to the ON position or approximately 20 s after all doors are closed.

Keyless Entry Interior Illumination

When the BCM receives a door unlock command from the remote keyless entry transmitter, the BCM will flash the park lamps several times, illuminate the courtesy and park lamps, and illuminate the low beam headlamps at low intensity. The lamps will remain on until the ignition key is turned from the OFF position, a keyless entry transmitter door lock command is received, or after an approximate 20 s delay.

Interior Lamps Dimming

This group includes lamps which may dim. This group may use a combination of vacuum fluorescent illumination, LEDs and incandescent lamps.

  1. HVAC control module, head assembly
  2. Rear HVAC control module, head assembly
  3. Radio
  4. Rear seat audio
  5. The instrument panel cluster
  6. The PRNDL lamp, with the exception of the current gear select position
  7. Power window switches
  8. Various switches

When the ignition switch is turned to the ON position, the vacuum fluorescent display, radio, turns ON at maximum brightness. When the park lamps or low beams are ON, all incandescent back lighting turn ON at the dimming level indicated by the instrument panel cluster dimmer switch. At the same time all fluorescent display displays dim to match the indicated dimming level. When the headlamp switch is placed in the PARK or in HEADLAMPS position, the headlamp switch supplies an input signal to the BCM. The BCM then supplies voltage to the instrument panel cluster dimmer switch through the dimming control circuit. The setting of the instrument panel cluster dimmer switch determines the amount of voltage that the instrument panel cluster dimmer switch supplies to the BCM. The BCM then sends a PWM voltage to all the interior lamps. All the fluorescent display and incandescent back lighting lamps are provided a specific voltage.

Note. For vehicles which are equipped with automatic light function, the interior backlighting can only be dimmed when the ambient light sensor detects night conditions.

When the headlight switch is turned to the park lamp or headlamp position, all incandescent back lighting turn ON at the dimming level indicated by the instrument panel cluster dimmer switch. When the instrument panel cluster dimmer switch is moved from minimum to maximum, all fluorescent display displays, as well as all incandescent back lighting respond from minimum intensity to maximum brightness in response to the instrument panel cluster dimmer switch.

Inadvertent Power

The BCM used in this vehicle controls the lighting system through circuits that enable the interior lamps. The BCM opens these enabling circuits shortly after the ignition switch is turned OFF with no lamp switch activity. If the ignition switch is turned to any position other than OFF, or if a lamp switch is activated during this period, the timer will reset itself.

See also:
• Diagnostic System Check - Vehicle
• Strategy Based Diagnosis
• Diagnostic Procedure Instructions
• COMPONENT CONNECTOR END VIEWS -- INDEX
• Circuit Testing
• Connector Repairs
• Testing for Intermittent Conditions and Poor Connections
• Wiring Repairs
• Control Module References
• Diagnostic Repair Verification
• Steering Wheel Secondary/Configurable Control Schematics
• Fuse Block Replacement
• Turn Signal Multifunction Switch Replacement
• Outside Rearview Mirror Replacement
• Backup Lamp Switch Replacement
• Cruise Control Schematics
• Cruise Control Description and Operation
• Checking Aftermarket Accessories
• Door Ajar Indicator Malfunction
• Instrument Panel Lower Trim Panel Insulator Replacement
• Fastener Caution
• Inside Rearview Mirror Mount Plate Cover Replacement
• Avoid Touching the Bulb Caution
• Front Bumper Fascia Replacement
• Halogen Bulb Warning
• Lifting and Jacking the Vehicle
• Body Control Module Replacement (Left Hand Drive)
• Front Wheelhouse Front Liner Replacement
• Windshield Washer Solvent Container Replacement
• DTC B096A
• Brake Pedal Position Sensor Calibration
• Brake Pedal Position Sensor Replacement