Pinpoint Test D: One Low Beam Headlamp Is Inoperative

WARNING: This page is about a different car, the 2006 Ford F550 Super Duty, 2006 Ford F450 Super Duty, and 2006 Ford Cab & Chassis. However, it is still accessible from the selected car via links, so may be relevant.

D1 CHECK THE VOLTAGE TO THE INOPERATIVE HEADLAMP

Key in OFF position.
Disconnect: Inoperative Headlamp.
Place the headlamp switch in the headlamps ON position.
Place the multifunction switch in the LOW BEAM position.

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

CONNECTOR-PIN CIRCUIT

Inoperative Headlamp (Type)	Connector-Pin	Circuit
LH headlamp (aerodynamic)	C1021-3	160 (DB/WH)
RH headlamp (aerodynamic)	C1041-3	161 (DG/OG)
LH headlamp (sealed beam)	C1284-3	160 (DB/WH)
RH headlamp (sealed beam)	C1285-3	161 (DG/OG)

Fig 1: Checking Voltage To Inoperative Headlamp

Courtesy of FORD MOTOR CO.

Is the voltage greater than 10 volts?

Yes : REPAIR circuit 57 (BK). TEST the system for normal operation.

No : PLACE the headlamp switch in the OFF position, GO to D2.

D2 CHECK THE CJB
- Disconnect: CJB C270f.
- Place the headlamp switch in the headlamps ON position.
- Measure the voltage between the CJB C270f pin 2, circuit 161 (DG/OG), component side and ground; or between the CJB C270f pin 3, circuit 160 (DB/WH), component side and ground.
  
  Fig 2: Checking CJB
  Courtesy of FORD MOTOR CO.
- Is the voltage greater than 10 volts?
Yes : REPAIR the circuit in question. TEST the system for normal operation.

No : VERIFY the CJB fuse 46 (10A) (LH headlamp) or 47 (10A) (RH headlamp) is OK. If OK, INSTALL a new CJB. TEST the system for normal operation.