Pinpoint Test B: One Low Beam Headlamp Is Inoperative

WARNING: This page is about a different car, the 2004 Mercury Monterey and 2004 Ford Freestar. However, it is still accessible from the selected car via links, so may be relevant.

B1 USE THE RECORDED DTCs FROM THE SJB SELF-TEST
- Key in OFF position.
- Using the recorded results from the SJB self-test:
- Were any DTCs recorded?
Yes

If DTC B2501 or B2503, GO to B2.

Any other DTCs, refer to the SMART JUNCTION BOX (SJB) DIAGNOSTIC TROUBLE CODE (DTC) INDEX for correct diagnostics.

No

GO to B7.
B2 CHECK CIRCUIT 1205 (BK) FOR AN OPEN
- Place the headlamp switch to the headlamps ON position.
- Place the multifunction switch to the high beam position.
- Does the inoperative headlamp now illuminate?
Yes

TURN the headlamp switch OFF. GO to B5.

No

If RH headlamp, REPAIR the circuit. CLEAR any DTCs. TEST the system for normal operation.

If LH headlamp, TURN the headlamp switch OFF. GO to B3.
B3 CHECK THE LH HEADLAMP GROUND CIRCUIT
- Key in OFF position.
- Disconnect: LH Headlamp C1021.
- Measure the resistance between LH headlamp C1021-2, circuit 1205 (BK), harness side and ground.
- Is the resistance less than 5 ohms?
Yes

GO to B7.

No

GO to B4.
B4 CHECK CIRCUIT 1205 (BK) FOR AN OPEN (LH HEADLAMP)
- Disconnect: BEC C1035c.
- Measure the resistance between LH headlamp C1021-2, circuit 1205 (BK), harness side and BEC C1035c-E1, circuit 1205 (BK), harness side.
  
  Fig 2: Measuring Resistance Between LH Headlamp C1021-2, Circuit 1205 (BK), Harness Side And BEC C1035C-E1, Circuit 1205 (BK), Harness Side
  Courtesy of FORD MOTOR CO.
- Is the resistance less than 5 ohms?
Yes

REPAIR or INSTALL a new BEC. CLEAR any DTCs. TEST the system for normal operation.

No

REPAIR the circuit. CLEAR any DTCs. TEST the system for normal operation.
B5 CHECK CIRCUIT 1336 (LG/WH) (RH HEADLAMP) OR 1338 (WH) (LH HEADLAMP) FOR AN OPEN
- Key in OFF position.
- Disconnect: Inoperative Headlamp.
- Measure the resistance between SJB C2280d-48, circuit 1336 (LG/WH) (RH headlamp), harness side and RH headlamp C1041-1, circuit 1336 (LG/WH), harness side; or between SJB C2280d-51, circuit 1338 (WH) (LH headlamp), harness side and LH headlamp C1021-1, circuit 1338 (WH), harness side.
  
  Fig 3: Checking Circuit 1336 (LG/WH) (RH Headlamp) Or 1338 (WH) (LH Headlamp) For An Open
  Courtesy of FORD MOTOR CO.
- Is the resistance less than 5 ohms?
Yes

GO to B6.

No

REPAIR the circuit in question. CLEAR any DTCs. TEST the system for normal operation.
B6 CHECK CIRCUIT 1336 (LG/WH) (RH HEADLAMP) OR 1338 (WH) (LH HEADLAMP) FOR A SHORT TO GROUND
- Measure the resistance between SJB C2280d-48, circuit 1336 (LG/WH) (RH headlamp), harness side and ground; or between SJB C2280d-51, circuit 1338 (WH) (LH headlamp), harness side and ground.
  
  Fig 4: Check Circuit 1336 (LG/WH) (RH Headlamp) Or 1338 (WH) (LH Headlamp) For A Short To Ground
  Courtesy of FORD MOTOR CO.
- Is the resistance greater than 10,000 ohms?
Yes

GO to B7.

No

REPAIR the circuit in question. CLEAR any DTCs. TEST the system for normal operation.
B7 CHECK FOR SJB OPERATION
- Key in OFF position.
- Disconnect all the SJB connectors.
- Check for:
  - Corrosion
  - 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 SMART JUNCTION BOX (SJB) . TEST the system for normal operation.

No

The system is operating correctly at this time. Concern may have been caused by a loose or corroded connector. CLEAR any DTCs. REPEAT the self-test.