Pinpoint Test O: The Exterior Lamps Are Inoperative

WARNING: This page is about a different car, the 2005 Ford Pickup, 2005 Ford F550 Super Duty, 2005 Ford F450 Super Duty, and 2005 Ford Cab & Chassis. However, it is still accessible from the selected car via links, so may be relevant.

O1 CHECK VOLTAGE TO THE HEADLAMP SWITCH
- Disconnect: Headlamp Switch C205a.
- Measure the voltage between headlamp switch C205a-10, circuit 195 (TN/WH), harness side and ground.
  
  Fig 1: Checking Voltage To Headlamp Switch
  Courtesy of FORD MOTOR CO.
- Is the voltage greater than 10 volts?
- Yes : GO to O3.
- No : GO to O2.
O2 CHECK CIRCUIT 195 (TN/WH) FOR AN OPEN
- Disconnect: Central Junction Box (CJB) C270b.
- Measure the resistance between headlamp switch C205a-10, circuit 195 (TN/WH), harness side and central junction box (CJB) C270b-10, circuit 195 (TN/WH), harness side.
  
  Fig 2: Checking Circuit 195 (TN/WH) For Open
  Courtesy of FORD MOTOR CO.
- Is the resistance less than 5 ohms?
- Yes : INSTALL a new CJB. TEST the system for normal operation.
- No : REPAIR the circuit. TEST the system for normal operation.
O3 CHECK THE HEADLAMP SWITCH
- Carry out the headlamp component test. Refer to COMPONENT TESTING .
- Is the headlamp switch OK?
- Yes : GO to O4.
- No : INSTALL a new headlamp switch. REFER to LAMP SWITCH - HEADLAMP . TEST the system for normal operation.
O4 CHECK CIRCUIT 14 (BN) FOR AN OPEN
- Disconnect: Central Junction Box (CJB) C270b.
- Measure the resistance between headlamp switch C205a-12, circuit 14 (BN), harness side and CJB C270b-5, circuit 14 (BN), harness side.
  
  Fig 3: Checking Circuit 14 (BN) For Open
  Courtesy of FORD MOTOR CO.
- Is the resistance less than 5 ohms?
- Yes : INSTALL a new CJB. TEST the system for normal operation.
- No : REPAIR the circuit. TEST the system for normal operation.