B2126

B2126-00-SENSOR SUPPLY VOLTAGE LOW





For a complete wiring diagram, refer to the Wiring Information.

Theory of Operation

The Front and Rear Headlamp Level Sensors monitor changes in the relative distance between the vehicle body and the front or rear suspension members. In vehicles with High Intensity Discharge (HID) Headlamps but without the air suspension system, the sensor circuitry is energized by the Automatic Headlamp Leveling Module (AHLM) and both sensors provide hard wired inputs back to the AHLM. The AHLM uses these sensor inputs as logic for calculating when and how much to adjust the headlamp beams as part of the Automatic Headlamp Leveling feature.

- When Monitored:
With the ignition on.

- Set Condition:
The Auto Headlamp Leveling Module (AHLM) detects a low condition on the (L961) Headlamp Leveling Sensor 5 Volt Supply Circuit.





1. CHECK FOR AN ACTIVE DTC
1. Turn the ignition on.
2. With the scan tool, read DTCs.

Does the scan tool display this DTC as active?

Yes

- Go To 2

No

- Test complete, the condition or conditions that originally set this DTC are not present at this time. Using the wiring diagrams as a guide, check all related splices and connectors for signs of water intrusion, corrosion, pushed out or bent terminals, and correct pin tension.
- Perform the BODY VERIFICATION TEST. Body Verification Test.

2. FRONT HEADLAMP LEVEL SENSOR
1. Turn the ignition off.
2. Disconnect Front Headlamp Level Sensor.
3. Turn the ignition on.
4. With the scan tool, read DTCs.

Does the scan tool display this DTC as active?

Yes

- Go To 3

No

- Replace Front Headlamp Level Sensor. Front.
- Perform the BODY VERIFICATION TEST. Body Verification Test.

3. REAR HEADLAMP LEVELING SENSOR
1. Turn the ignition off.
2. Disconnect Rear Headlamp Level Sensor.
3. Turn the ignition on.
4. With the scan tool, read DTCs.

Does the scan tool display this DTC as active?

Yes

- Go To 4

No

- Replace Rear Headlamp Level Sensor. Rear.
- Perform the BODY VERIFICATION TEST. Body Verification Test.

4. (L961) HEADLAMP LEVELING SENSOR 5 VOLT SUPPLY CIRCUIT SHORTED TO GROUND




1. Turn the ignition off.
2. Disconnect the Right Front Headlamp Assembly C2 harness connector.
3. Measure the resistance between ground and the (L961) Headlamp Leveling Sensor 5 Volt Supply circuit.

Is the resistance below 10K Ohms?

Yes

- Repair the short to ground on the (L961) Headlamp Leveling Sensor 5 Volt Supply circuit.
- Perform the BODY VERIFICATION TEST. Body Verification Test.

No

- Replace the Auto Headlamp Leveling Module (AHLM). Headlamp Leveling Module - Removal.
- Perform the BODY VERIFICATION TEST. Body Verification Test.