Pinpoint Test C: One Low Beam Headlamp Is Inoperative: Testing

WARNING: This page is about a different car, the 2005 Mercury Montego, 2005 Ford Freestyle, and 2005 Ford Five Hundred. However, it is still accessible from the selected car via links, so may be relevant.

C1 CHECK CIRCUIT 1205 (BK) FOR AN OPEN

Key in OFF position.
Disconnect: Inoperative Headlamp.

Measure the resistance between the inoperative headlamp, harness side and ground as follows:

CONNECTOR-PIN REFERENCE

Vehicle	Inoperative Headlamp	Connector-Pin	Circuit
Freestyle	LH	C1021-2	1205 (BK)
Freestyle	RH	C1041-2	1205 (BK)
Five Hundred	LH	C1020-1	1205 (BK)
Five Hundred	RH	C1112-1	1205 (BK)
Montego	LH	C1284-4	1205 (BK)
Montego	RH	C1285-4	1205 (BK)

Is the resistance less than 5 ohms?

Yes : For Montego, GO to C2.
For Freestyle or Five Hundred, GO to C3.
No : REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test.

C2 CHECK CIRCUIT 1336 (LG/WH) OR CIRCUIT 1338 (WH) FOR VOLTAGE
- Place the headlamp switch in the HEADLAMPS ON position.
- Measure the voltage between the LH headlamp C1284-1, circuit 1338 (WH), harness side and ground; or between the RH headlamp C1285-1, circuit 1336 (LG/WH), harness side and ground.
  
  Fig 1: Checking Circuit 1336 (LG/WH) Or Circuit 1338 (WH) For Voltage
  Courtesy of FORD MOTOR CO.
- Is the voltage greater than 10 volts?
- Yes : TURN the headlamps off. GO to C4.
- No : TURN the headlamps off. GO to C3.

C3 CHECK CIRCUIT 1336 (LG/WH) OR CIRCUIT 1338 (WH) FOR AN OPEN

Disconnect: SJB C2280a.

Measure the resistance between the inoperative headlamp, harness side and the SJB, harness side as follows:

SJB CONNECTOR-PIN REFERENCE

Vehicle	Inoperative Headlamp Connector-Pin	SJB Connector-Pin	Circuit
Freestyle	LH C1021-1	C2280a-9	1338 (WH)
Freestyle	RH C1041-1	C2280a-l	1336 (LG/WH)
Five Hundred	LH C1020-2	C2280a-9	1338 (WH)
Five Hundred	RH C1112-2	C2280a-l	1336 (LG/WH)
Montego	LH C1284-1	C2280a-9	1338 (WH)
Montego	RH C1285-1	C2280a-l	1336 (LG/WH)

Is the resistance less than 5 ohms?

Yes : GO to C7.
No : REPAIR the circuit in question. CLEAR the DTCs. REPEAT the self-test.

C4 CHECK CIRCUIT 1779 (DB/LG) OR CIRCUIT 1724 (WH/LG) FOR AN OPEN
- Measure the voltage between the LH headlamp C1284-6, circuit 1724 (WH/LG), harness side and ground; or between the RH headlamp C1285-6, circuit 1779 (DB/LG), harness side and ground.
  
  Fig 2: Checking Circuit 1779 (DB/LG) Or Circuit 1724 (WH/LG) For Open
  Courtesy of FORD MOTOR CO.
- Is the voltage greater than 10 volts?
- Yes : GO to C5.
- No : VERIFY the BJB fuse 31 (20A) (LH headlamp) or fuse 20 (20A) (RH headlamp) is OK. If OK, REPAIR the circuit in question. CLEAR the DTCs. REPEAT the self-test.
C5 CHECK THE BALLAST
- Substitute a known good ballast.
- Place the headlamp switch in the HEADLAMPS ON position
- Does the inoperative low beam now illuminate?
- Yes : INSTALL a new ballast. REFER to BALLAST . CLEAR the DTCs. REPEAT the self-test.
- No : TURN the headlamps off. INSTALL the original ballast. GO to C6.
C6 CHECK THE HID BULB
- Substitute a known good HID bulb.
- Place the headlamp switch in the HEADLAMPS ON position.
- Does the inoperative low beam now illuminate?
- Yes : INSTALL a new HID bulb. REFER to HEADLAMP BULB . CLEAR the DTCs. REPEAT the self-test.
- No : INSTALL a new headlamp assembly. REFER to HEADLAMP ASSEMBLY - FIVE HUNDRED, MONTEGO . CLEAR the DTCs. REPEAT the self-test.
C7 CHECK FOR CORRECT SJB OPERATION
- 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 MULTIFUNCTION ELECTRONIC MODULES . 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.