B3440
DTC B3435 or B3440
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions Diagnostic Procedure Instructions provides an overview of each diagnostic category.
DTC Descriptors
DTC B3435 00
- AHLD Left Servo Driver Circuit
DTC B3435 03
- AHLD Left Servo Driver Circuit Short to Ground
DTC B3440 00
- AHLD Right Servo Driver Circuit
DTC B3440 03
- AHLD Right Servo Driver Circuit Short to Ground
Diagnostic Fault Information
Circuit/System Description
Each headlamp assembly contains a headlamp leveling actuator that is controlled by the headlamp leveling control module. The front and rear suspension position sensors provide the headlamp leveling control with suspension position information. Each sensor receives a 5 V reference, signal, and low reference circuits from the headlamp leveling 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 leveling control module compares the information from both suspension position sensors and adjusts the headlamp leveling as needed. The headlamp leveling control module communicates with the left and right headlamp leveling actuators via the LIN serial data circuit.
Conditions for Running the DTC
* Battery voltage must be between 9-16 V.
* Ignition ON.
* Headlamps ON.
Conditions for Setting the DTC
DTC B3435 00
* The headlamp leveling control module detects a short to ground or an open/high resistance in the left headlamp leveling actuator LIN bus circuit.
* The headlamp leveling control module detects an open/high resistance in the left headlamp leveling actuator ground circuit.
DTC B3435 03
* The headlamp leveling control module detects a short to ground or an open/high resistance in the left headlamp leveling actuator B+ circuit.
* The headlamp leveling control module detects an open/high resistance in the left headlamp leveling actuator ground circuit.
DTC B3440 00
* The headlamp leveling control module detects a short to ground or an open/high resistance in the right headlamp leveling actuator LIN bus circuit.
* The headlamp leveling control module detects an open/high resistance in the right headlamp leveling actuator ground circuit.
DTC B3440 03
* The headlamp leveling control module detects a short to ground or an open/high resistance in the right headlamp leveling actuator B+ circuit.
* The headlamp leveling control module detects an open/high resistance in the right headlamp leveling actuator ground circuit.
Actions Taken When the DTC Sets
* When DTC B3435 or DTC B3440 sets, the headlamp leveling control module will attempt to return the lamps to a nominal position and disable all requests to all headlamp actuators.
* The instrument cluster will display Headlamp Leveling Malfunction - Contact Service.
Conditions for Clearing the DTC
* The condition responsible for setting the DTC no longer exists and the ignition is cycled.
* A history DTC will clear once 50 consecutive malfunction-free ignition cycles have occurred.
Reference Information
Schematic Reference
Headlights/Daytime Running Lights (DRL) Schematics Headlights/Daytime Running Lights (DRL) Schematics
Connector End View Reference
Component Connector End Views Fuel Pump and Level Sensor Assembly
Description and Operation
Exterior Lighting Systems Description and Operation Exterior Lighting Systems
Electrical Information Reference
* Circuit Testing Circuit Testing
* Connector Repairs Connector Repairs
* Testing for Intermittent Conditions and Poor Connections Testing for Intermittent Conditions and Poor Connections
* Wiring Repairs Wiring Repairs
Scan Tool Reference
Control Module References Control Module References for scan tool information
Circuit/System Testing
1. Ignition OFF, exterior lamps OFF, disconnect the harness connector at the appropriate M29 headlamp leveling actuator.
2. Test for less than 5 ohms between the ground circuit terminal 2 and ground.
• If 5 ohms or greater
1. Ignition OFF.
2. Test for less than 2 ohms in the ground circuit end to end.
• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, repair the open/high resistance in the ground connection.
• If less than 5 ohms
3. Ignition ON.
4. Verify a test lamp illuminates between the B+ circuit terminal 1 and ground.
• If the test lamp does not illuminate
1. Ignition OFF, disconnect the X2 harness connector at the X50A fuse block - underhood.
2. Test for infinite resistance between the B+ circuit and ground.
• If less than infinite resistance, repair the short to ground on the circuit.
• If infinite resistance
3. Test for less than 2 ohms in the control circuit end to end.
• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, replace the X50A fuse block - underhood.
• If the test lamp illuminates
5. Test or replace the K26 headlamp control module.
6. Ignition ON.
7. Verify the appropriate headlamp operates to the UP and DOWN positions when commanding the DHL Motor Control UP and DOWN with a scan tool.
• If the appropriate headlamp does not operate UP and DOWN, test or replace the appropriate headlamp assembly.
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the repair.
* Headlamp Replacement Headlamp Replacement
* Control Module References Control Module References for headlamp leveling control module replacement, programming, and setup