For 1990-2009 cars

### 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: Automatic Headlamp Leveling Control Module Front Axle Sensor Signal Circuit Short to Ground
DTC B3410 05: Automatic Headlamp Leveling Control Module Front Axle Sensor Signal Circuit Open or High Voltage
DTC B3410 08: Automatic Headlamp Leveling Control Module Front Axle Sensor Signal Circuit Performance or Signal Invalid
DTC B3420 02: Automatic Headlamp Leveling Control Module Rear Axle Sensor Signal Circuit Short to Ground
DTC B3420 05: Automatic Headlamp Leveling Control Module Rear Axle Sensor Signal Open Circuit or High Voltage
DTC B3420 08: Automatic Headlamp Leveling Control Module Rear Axle Sensor Signal Circuit Performance or Signal Invalid

### Diagnostic Fault Information

Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance
--- | --- | --- | --- | ---
Headlamp Leveling Sensor 5 V Reference - Front | B3415 02 | 1 | B3415 01 | --
Headlamp Leveling Sensor 5 V Reference - Rear | B3415 02 | 1 | B3415 01 | --
Headlamp Leveling Sensor Signal - Front | B3410 02 | B3410 05 | B3410 05 | B3410 08
Headlamp Leveling Sensor Signal - Rear | B3420 02 | B3420 05 | B3420 05 | B3420 08
Headlamp Leveling Sensor Low Reference - Front | -- | 1 | -- | --
Headlamp Leveling Sensor Low Reference - Rear | -- | 1 | -- | --
1. Headlamp Leveling Malfunction

### Circuit/System Description

The front and rear suspension position sensors provide the headlamp control module with front and rear 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 at 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 sensors to change. The headlamp control module compares the information from the front and rear suspension position sensors and adjusts the headlamp leveling as needed.

### Conditions for Running the DTC

• | Battery voltage must be between 9-16 V.

• | The ignition is in the ON or RUN position.

• | The headlamps are 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.

#### B3410 05 or B3420 05

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

#### B3410 08 or B3420 08

The DTC will set when the headlamp control module detects sensor frequency out of range or sensor signal implausible.

### Action Taken When the DTC Sets

• | The headlamp control module disables the headlamp leveling system.

• | service head light leveling indication ON.

• | Advanced front lighting system fault indication ON.

### Conditions for Clearing the DTC

The condition responsible for setting the DTC no longer exists.

### Reference Information

#### Schematic Reference

Headlight Leveling Schematics

#### Connector End View Reference

Component Connector End Views

#### 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 Verification

Verify that DTC B3415 is not present.

⇒ | If DTC is present, refer to DTC B3415

### Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the appropriate headlamp leveling sensor.
2. Ignition OFF, test for less than 5 Ω between the low reference circuit terminal 3 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 K26 Headlamp Control Module.

3. Ignition ON, test for 4.8-5.2 V between the 5 V reference circuit terminal 1 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 K26 Headlamp Control Module.

⇒ | If greater than the specified range, test the 5 V reference circuit for a short to voltage. If the circuit tests normal, replace the K26 Headlamp Control Module.

4. Verify the appropriate scan tool Leveling Position Sensor parameter is less than 0 mm.

⇒ | If greater than the specified range, test the signal circuit terminal 2 for a short to voltage. If the circuit tests normal, replace the K26 Headlamp Control Module.

5. Install a 3 A fused jumper wire between the signal circuit terminal 2 and the 5 V reference circuit terminal 1. Verify the appropriate scan tool Leveling Position Sensor parameter is greater than 0 mm.

⇒ | 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 K26 Headlamp Control Module.

6. If all circuits test normal, replace the appropriate headlamp leveling sensor.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Headlamp Leveling Front Suspension Height Sensor Replacement

• | Headlamp Leveling Rear Suspension Height Sensor Replacement

• | Control Module References for headlamp control module replacement, setup, and programming