Pinpoint Test D: One Low Beam Headlamp Is Inoperative
Headlamps
Pinpoint Test
Pinpoint Test D: One Low Beam Headlamp Is Inoperative
Refer to Wiring Diagram Set 85, Headlamps/Autolamps for schematic and connector information. Diagrams By Number
Normal Operation
When the headlamp switch is placed in the HEADLAMPS ON position, the Smart Junction Box (SJB) routes voltage to the LH and RH low beams. Each headlamp has a dedicated ground circuit.
This pinpoint test is intended to diagnose the following:
- Fuse
- Wiring, terminals or connectors
- SJB
PINPOINT TEST D: ONE LOW BEAM HEADLAMP IS INOPERATIVE
NOTICE: Use the correct probe adapter(s) when making measurements. Failure to use the correct probe adapter(s) may damage the connector.
-------------------------------------------------
D1 CHECK THE HEADLAMP GROUND CIRCUIT FOR AN OPEN
- Ignition OFF.
- Place the headlamp switch in the HEADLAMPS ON position.
- Place the multifunction switch in the HIGH BEAM position.
- Does the headlamp with the inoperative low beam illuminate?
Yes
VERIFY the SJB fuse 4 (10A) (LH low beam) or fuse 3 (10A) (RH low beam) is OK. If OK, GO to D2. If not OK, REFER to the Wiring Diagrams to identify the possible causes of the circuit short. Diagrams By Number
No
REPAIR circuit GD121 (BK/YE) (LH headlamp) or circuit GD123 (BK/GY) (RH headlamp) for an open. TEST the system for normal operation.
-------------------------------------------------
D2 CHECK THE SJB LOW BEAM OUTPUT CIRCUIT FOR AN OPEN
- Place the headlamp switch in the OFF position.
- Disconnect: Inoperative Headlamp.
- Disconnect: SJB C2280a.
- Measure the resistance between the LH headlamp C1021-1, circuit CBP04 (VT), harness side and the SJB C2280a-16, circuit CBP04 (VT), harness side; or between the RH headlamp C1041-1, circuit CBP03 (GY), harness side and the SJB C2280a-20, circuit CBP03 (GY), harness side.
- Is the resistance less than 5 ohms?
Yes
GO to D3.
No
REPAIR circuit CBP04 (VT) or circuit CBP03 (GY) for an open. TEST the system for normal operation.
-------------------------------------------------
D3 CHECK FOR CORRECT SJB OPERATION
- Disconnect all the SJB connectors.
- Check for:
- corrosion
- damaged pins
- pushed-out pins
- Connect all the SJB connectors and make sure they seat correctly.
- Operate the system and verify the concern is still present.
- Is the concern still present?
Yes
INSTALL a new SJB. REFER to Body Control Systems. TEST the system for normal operation.
No
The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector.
-------------------------------------------------