The rear suspension position sensor provides the headlamp leveling modules with rear suspension position information. The sensor is permanently grounded and has voltage supplied with the ignition in the ON or CRANK position. The sensor arm is connected to the control arm of the rear suspension. As the vehicle travels, the suspension compresses and rebounds moving the suspension position sensor arm. This causes the signal output of the sensor to change. The headlamp leveling modules compare this information with the front suspension position sensor information and adjusts the headlamp leveling as needed. For more detailed information concerning headlamp leveling operation, refer to Exterior Lighting Systems Description and Operation .

DTC B3420 00 will set when the headlamp leveling module detects a fault, an internal counter in each of the headlamp leveling modules is increased by 1. When the counter reaches 5 the DTC is set as current.

When DTC B3410 00 is present, the headlamp leveling modules use an internal offset of the headlamp leveling sensor front in order to keep the leveling system active.

Important: When one of the suspension position sensor voltage reference or sensor signal circuits are shorted to ground, it may not be possible to determine which suspension position sensor voltage reference or sensor signal circuits, front or rear, has failed. If this condition occurs, all suspension position sensor voltage reference and sensor signal circuits will have to be tested for a short to ground.

Schematic Reference

Headlight Leveling Schematics

Connector End View Reference

Lighting Systems Connector End Views

Electrical Information Reference

Scan Tool Reference

1. Ignition OFF, disconnect the harness connector at the rear headlamp leveling sensor.
2. Ignition OFF, test for less than 1.0 ohm of resistance between the ground circuit terminal C and ground.

⇒	If greater than the specified range, test the ground circuit for an open/high resistance.

3. Ignition ON, test for B+ between the voltage reference circuit terminal A and ground.

⇒	If less than the specified range, test the voltage reference circuit for a short to ground or an open/high resistance.

4. Disconnect the C 112 harness connector at the right headlamp assembly.
5. Ignition ON, verify that a test lamp does not illuminate between the rear headlamp leveling switch signal circuit terminal B and ground.

⇒	If the test lamp illuminates, test the signal circuit for a short to voltage. If the circuit tests normal, test or replace the left headlamp assembly.

6. Disconnect the C 111 harness connector at the left headlamp assembly.
7. Ignition OFF, verify that a test lamp does not illuminate between the rear headlamp leveling switch signal circuit terminal B and B+.

⇒	If the test lamp illuminates, test the signal circuit terminal B for a short to ground.

8. Ignition OFF, verify that a test lamp does not illuminate between the rear headlamp leveling switch signal circuit terminal E and B+.

⇒	If the test lamp illuminates, test the signal circuit terminal E for a short to ground.

9. Disconnect the harness connector at the front headlamp leveling sensor.
10. Ignition OFF, verify that a test lamp does not illuminate between the front headlamp leveling switch signal circuit terminal 4 and B+.

⇒	If the test lamp illuminates, test the signal circuit terminal 4 for a short to ground.

11. Connect the C 111 harness connector at the left headlamp assembly.
12. Verify with a DMM that continuity is present between the rear headlamp leveling switch signal circuit terminal B and terminal E at the C 112 harness connector at the right headlamp assembly.

⇒	If continuity is not present, test the signal circuit for an open/high resistance. If the circuit tests normal, test or replace the left headlamp assembly.

13. If all circuits test normal, test or replace the rear headlamp leveling sensor.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.