Pinpoint Test C: One Low Beam Headlamp Is Inoperative - Halogen Headlamps
Headlamps
Pinpoint Tests
Pinpoint Test C: One Low Beam Headlamp Is Inoperative - Halogen Headlamps
Refer to Wiring Diagram Set 85, Headlamps for schematic and connector information. Diagrams By Number
Refer to Wiring Diagram Set 11, Fuse and Relay Information for schematic and connector information. Diagrams By Number
Normal Operation
When the Smart Junction Box (SJB) receives a request for the low beams, the SJB provides voltage to circuits 1338 (WH) and 1336 (LG/WH), through the Bussed Electrical Center (BEC)), to the LH and RH low beams, respectively. Ground for the low beams is provided through circuit 1205 (BK), which is routed through the BEC.
- DTC B2501 (LF Lamp Low Beam Circuit Failure) - a continuous and on-demand DTC that sets when the SJB detects an open or short to ground from the LH headlamp voltage supply circuit.
- DTC B2503 (RF Lamp Low Beam Circuit Failure) - a continuous and on-demand DTC that sets when the SJB detects an open or short to ground from the RH headlamp voltage supply circuit.
This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- BEC
- SJB
PINPOINT TEST C: ONE LOW BEAM HEADLAMP IS INOPERATIVE - HALOGEN HEADLAMPS
NOTICE: Use the correct probe adapter(s) when making measurements. Failure to use the correct probe adapter(s) may damage the connector.
NOTE: Make sure the bulb is good before continuing diagnostics.
NOTE: Failure to disconnect the battery when instructed will result in false resistance readings. Refer to Battery.
-------------------------------------------------
C1 CHECK THE HEADLAMP GROUND CIRCUIT
- Ignition OFF.
- Disconnect: Negative Battery Cable.
- Disconnect: Inoperative Headlamp.
- Measure the resistance between the LH headlamp C1021-2, circuit 1205 (BK), harness side and ground; or between the RH headlamp C1041-2, circuit 1205 (BK), harness side and ground.
- Is the resistance less than 5 ohms?
Yes
GO to C4.
No
GO to C2.
-------------------------------------------------
C2 CHECK CIRCUIT 1205 (BK) FOR AN OPEN (HEADLAMP TO BEC)
- Disconnect: BEC C1035c.
- Measure the resistance between the LH headlamp C1021-2, circuit 1205 (BK), harness side and the BEC C1035c-D5, circuit 1205 (BK), harness side; or between the RH headlamp C1041-2, circuit 1205 (BK), harness side and the BEC C1035c-D11, circuit 1205 (BK), harness side.
- Is the resistance less than 5 ohms?
Yes
GO to C3.
No
REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test.
-------------------------------------------------
C3 CHECK CIRCUIT 1205 (BK) FOR AN OPEN (BEC TO GROUND)
- Measure the resistance between the BEC C1035c-F5 (LH headlamp), circuit 1205 (BK), harness side and ground; or between the BEC C1035c-E11 (RH headlamp), circuit 1205 (BK), harness side and ground.
- Is the resistance less than 5 ohms?
Yes
INSTALL a new BEC. CLEAR the DTCs. REPEAT the self-test.
No
REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test.
-------------------------------------------------
C4 CHECK CIRCUIT 1336 (LG/WH) OR CIRCUIT 1338 (WH) FOR A SHORT TO GROUND
- Connect: Negative Battery Cable.
- Disconnect: SJB C2280d.
- Measure the resistance between the LH headlamp C1021-1, circuit 1338 (WH), harness side and ground; or between the RH headlamp C1041-1, circuit 1336 (LG/WH), harness side and ground.
- Is the resistance greater than 10,000 ohms?
Yes
GO to C7.
No
GO to C5.
-------------------------------------------------
C5 CHECK CIRCUIT 1336 (LG/WH) OR CIRCUIT 1338 (WH) FOR A SHORT TO GROUND (SJB TO BEC)
- Disconnect: BEC C1035a.
- Measure the resistance between the LH headlamp C1021-1, circuit 1338 (WH), harness side and ground; or between the RH headlamp C1041-1, circuit 1336 (LG/WH), harness side and ground.
- Is the resistance greater than 10,000 ohms?
Yes
REPAIR the circuit in question. CLEAR the DTCs. REPEAT the self-test.
No
GO to C6.
-------------------------------------------------
C6 CHECK CIRCUIT 1336 (LG/WH) OR CIRCUIT 1338 (WH) FOR A SHORT TO GROUND (BEC TO HEADLAMP)
- Disconnect: BEC C1035c.
- Measure the resistance between the LH headlamp C1021-1, circuit 1338 (WH), harness side and ground; or between the RH headlamp C1041-1, circuit 1336 (LG/WH), harness side and ground.
- Is the resistance greater than 10,000 ohms?
Yes
INSTALL a new BEC. CLEAR the DTCs. REPEAT the self-test.
No
REPAIR the circuit in question. CLEAR the DTCs. REPEAT the self-test.
-------------------------------------------------
C7 CHECK CIRCUIT 1336 (LG/WH) OR CIRCUIT 1338 (WH) FOR AN OPEN (BEC TO HEADLAMP)
- Disconnect: BEC C1035c.
- Measure the resistance between the BEC C1035c-A6, circuit 1338 (WH), harness side and the LH headlamp C1021-1, circuit 1338 (WH), harness side; or between the BEC C1035c-A2, circuit 1336 (LG/WH), harness side and the RH headlamp C1041-1, circuit 1336 (LG/WH), harness side.
- Is the resistance less than 5 ohms?
Yes
GO to C8.
No
REPAIR the circuit in question. CLEAR the DTCs. REPEAT the self-test.
-------------------------------------------------
C8 CHECK FOR VOLTAGE TO THE BEC
- Disconnect: BEC C1035a.
- Connect: SJB C2280d.
- Place the headlamp switch in the HEADLAMPS ON position.
- Measure the voltage between the BEC C1035a-F6 (LH headlamp), circuit 1338 (WH), harness side and ground; or between the BEC C1035a-F2 (RH headlamp), circuit 1336 (LG/WH), harness side and ground.
- Is the voltage greater than 10 volts?
Yes
INSTALL a new BEC. CLEAR the DTCs. REPEAT the self-test.
No
GO to C9.
-------------------------------------------------
C9 CHECK CIRCUIT 1336 (LG/WH) OR CIRCUIT 1338 (WH) FOR AN OPEN (SJB TO BEC)
- Place the headlamp switch in the OFF position.
- Disconnect: SJB C2280d.
- Measure the resistance between the BEC C1035a-F6 (LH headlamp), circuit 1338 (WH), harness side and the SJB C2280d-51, circuit 1338 (WH), harness side.
- Measure the resistance between the BEC C1035a-F2 (RH headlamp), circuit 1336 (LG/WH), harness side and the SJB C2280d-48, circuit 1336 (LG/WH), harness side.
- Is the resistance less than 5 ohms?
Yes
GO to C10.
No
REPAIR the circuit in question. CLEAR the DTCs. REPEAT the self-test.
-------------------------------------------------
C10 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. 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. CLEAR the DTCs. REPEAT the self-test.
-------------------------------------------------