Circuit Description
The headlamp leveling module receives inputs from the front and rear suspension position sensors to determine vehicle pitch. The suspension position sensors send an output to the headlamp leveling module as the vehicle suspension compresses and rebounds. The headlamp leveling module calculates the difference in vehicle pitch and sends a command to the headlamp leveling actuators. The headlamp leveling actuators drive the headlamps to the position commanded by the headlamp leveling module. The headlamp leveling module monitors the headlamp leveling actuator motor control circuits for proper circuit continuity and for shorts to ground or voltage. If a malfunction is detected, a DTC will be stored in memory.
DTC Descriptors
This diagnostic procedure supports the following DTC:
DTC B1458 AHLD Left Servo Driver Terminal 4 Circuit
DTC Symptom | DTC Symptom Descriptor |
|---|---|
02 | Short to Ground |
05 | Short to Battery or Open |
Conditions for Running the DTC
The headlamp leveling module performs this diagnostic test mode every 0.8 millisecond when the following conditions are met:
| • | The ignition is in the ON or CRANK position. |
| • | The headlamps are ON. |
Conditions for Setting the DTC
DTC B1458 02
Will set when the headlamp leveling module detects a short to ground in the left headlamp leveling actuator motor 4 control circuit after 4 consecutive monitoring cycles.
DTC B1458 05
Will set when the headlamp leveling module detects an open or short to voltage in the left headlamp leveling actuator motor 4 control circuit after 4 consecutive monitoring cycles.
Action Taken When the DTC Sets
When DTC B1458 sets, the headlamp leveling module will disable all requests to both headlamp leveling actuators.
Conditions for Clearing the DTC
| • | The condition responsible for setting the DTC no longer exists. |
| • | You issue a scan tool CLEAR DTCs command. |
| • | A history DTC will clear once 40 consecutive malfunction-free ignition cycles have occurred. |
Diagnostic Aids
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 .
Step | Action | Yes | No |
|---|---|---|---|
Schematic Reference: Headlight Leveling Schematics Connector End View Reference: Lighting Systems Connector End Views | |||
1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | |
2 | Is DTC B1458 02 present? | Go to Step 3 | Go to Step 6 |
3 | Test the left headlamp leveling motor 4 circuit for a short to ground. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | Go to Step 13 | Go to Step 4 |
4 |
Does the scan tool indicate DTC B1458 02 is current? | Go to Step 5 | Go to Step 9 |
5 | Test the left headlamp leveling motor low reference circuit for a short to ground. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | Go to Step 13 | Go to Step 10 |
6 | Test the left headlamp leveling motor 4 circuit for an open or short to voltage. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | Go to Step 13 | Go to Step 7 |
7 |
Does the scan tool indicate DTC B1458 05 is current? | Go to Step 8 | Go to Step 9 |
8 | Test the left headlamp leveling motor low reference circuit for an open or short to voltage. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | Go to Step 13 | Go to Step 10 |
9 | Inspect for poor connections at the harness connector of the headlamp leveling control module. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | Go to Step 13 | Go to Step 12 |
10 | Inspect for poor connections at the harness connector of the left headlamp leveling actuator. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | Go to Step 13 | Go to Step 11 |
11 | Replace the left headlamp leveling actuator. Refer to Headlamp Replacement . Did you complete the replacement? | Go to Step 13 | -- |
12 | Replace the headlamp leveling control module. Refer to Control Module References for replacement, setup, and programming. Did you complete the replacement? | Go to Step 13 | -- |
13 |
Does the DTC reset? | Go to Step 2 | System OK |
