Buick Regal: DTC B3410 or B3420

Diagnostic Instructions

• Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
• Review Strategy Based Diagnosis for an overview of the diagnostic approach.
• Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptors

DTC B3410 02

Headlamp Leveling Control Module Front Axle Sensor Signal Circuit Short to Ground

DTC B3410 05

Headlamp Leveling Control Module Front Axle Sensor Signal Circuit High Voltage/Open

DTC B3410 08

Headlamp Leveling Control Module Front Axle Sensor Signal Circuit Performance - Signal Invalid

DTC B3420 02

Automatic Headlamp Leveling Control Module Rear Axle Sensor Signal Circuit Short to Ground

DTC B3410 05

Headlamp Leveling Control Module Rear Axle Sensor Signal Circuit High Voltage/Open

DTC B3420 08

Headlamp Leveling Control Module Rear Axle Sensor Signal Circuit Performance - Signal Invalid

Diagnostic Fault Information

1. Headlamp Leveling Malfunction

Circuit/System Description

Each headlamp assembly contains a headlamp leveling motor that is controlled by the headlamp control module. The front and rear suspension position sensors provide the headlamp control module with suspension position information. Each sensor receives a 5 V reference, signal, and low reference circuits from the headlamp control module. The sensors are connected to the control arms of the front and rear suspension. As the vehicle travels, the suspension compresses and rebounds moving the suspension position sensor arms. This causes the signal output of the sensor to change. The headlamp control module compares the information from both suspension position sensors and adjusts the headlamp leveling as needed.

Conditions for Running the DTC

• Battery voltage must be between 9 - 16 V.
• Engine RUNNING.
• Headlamps ON.

Conditions for Setting the DTC

B3410 02 or B3420 02

The DTC will set when the headlamp control module detects no signal and low voltage on the sensor signal line.

Actions Taken When the DTC Sets

• The headlamp control module disables the headlamp leveling system.
• The driver information center will display AFL Lamps Need Service.
• On vehicles equipped with both AFL and headlamp leveling, the AFL system will remain active.

Conditions for Clearing the DTC

• The condition responsible for setting the DTC no longer exists.
• A history DTC will clear once 50 consecutive malfunction-free ignition cycles have occurred.

Reference Information

Schematic Reference

Headlights/Daytime Running Lights (DRL) Wiring Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

Exterior Lighting Systems Description and Operation

Electrical Information Reference

• Circuit Testing
• Connector Repairs
• Testing for Intermittent Conditions and Poor Connections
• Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information.

Circuit/System Testing

NOTE: When replacing a headlamp leveling sensor it is necessary to perform the Suspension Position Sensor Calibration.

1. Ignition OFF, disconnect the harness connector at the appropriate B51 Suspension Height Sensor, ignition ON.

2. Verify a test lamp illuminates between the low reference circuit terminal 2 and B+.

• If the test lamp does not illuminate

1. Ignition OFF, disconnect the harness connector at the K26 Headlamp Control Module.
2. Test for less than 2 Ω in the low reference circuit end to end.
   • If 2 Ω or greater, repair the open/high resistance in the circuit.
   • If less than 2 Ω, replace the K26 Headlamp Control Module.

• Go to next step: If the test lamp illuminates

3. Ignition ON.

4. Test for 4.8 - 5.2 V between the 5 V reference circuit terminal 1 and ground.

• If less than 4.8 V

1. Ignition OFF, disconnect the harness connector at the K26 Headlamp Control Module.
2. Test for infinite resistance between the 5 V reference circuit and ground.
   • If less than infinite resistance, repair the short to ground on the circuit.
   • Go to next step: If infinite resistance
3. Test for less than 2 Ω in the 5 V reference circuit end to end.
   • If 2 Ω or greater, repair the open/high resistance in the circuit.
   • If less than 2 Ω, replace the K26 Headlamp Control Module.

• If greater than 5.2 V

1. Ignition OFF, disconnect the harness connector at the K26 Headlamp Control Module, ignition ON.
2. Test for less than 1 V between the 5 V reference circuit and ground.
   • If 1 V or greater, repair the short to voltage on the circuit.
   • If less than 1 V, replace the K26 Headlamp Control Module.

• Go to next step: If between 4.8 - 5.2 V

5. Verify the appropriate scan tool Leveling Position Sensor Signal parameter is less than 5 %.

• If 5 % or greater

1. Ignition OFF, disconnect the harness connector at the K26 Headlamp Control Module, ignition ON.
2. Test for less than 1 V between the signal circuit terminal 3 and ground.

• If 1 V or greater, repair the short to voltage on the circuit.
• If less than 1 V, replace the K26 Headlamp Control Module.

• Go to next step: If less than 5 %

6. Install a 3 A fused jumper wire between the 5 V reference circuit terminal 1 and the signal circuit terminal 3.

7. Engine RUNNING, verify the appropriate scan tool Leveling Position Sensor Signal parameter is greater than 90 %.

• If less than 90 %

1. Ignition OFF, disconnect the harness connector at the K26 Headlamp Control Module.
2. Test for infinite resistance between the signal circuit and ground.
   • If less than infinite resistance, repair the short to ground on the circuit.
   • Go to next step: If infinite resistance
3. Test for less than 2 Ω in the signal circuit end to end.
   • If 2 Ω or greater, repair the open/high resistance in the circuit.
   • If less than 2 Ω, replace the K26 Headlamp Control Module.

• Go to next step: If 90 % or greater

8. Test or replace the appropriate B51 Suspension Height Sensor.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

• Suspension Position Sensor Calibration
• Control Module References for headlamp control module replacement, programming, and setup

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