Pinpoint Test I: One Or More STOPLAMPS 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.

I1 CHECK THE VOLTAGE TO THE STOPLAMP
- Disconnect: Inoperative Stoplamp.
- Engage the brake pedal.
- Measure the voltage between inoperative stoplamp connector circuit 9 (LG/OG) (LH) or circuit 5 (OG/LB) (RH), harness side and ground; or between inoperative high mounted stoplamp, circuit 511 (LG), harness side and ground.
  
  Fig 1: Checking Voltage To Stoplamp
  Courtesy of FORD MOTOR CO.
- Is the voltage greater than 10 volts?
- Yes : REPAIR circuit 57 (BK). TEST the system for normal operation.
- No : If high mounted stoplamp, REPAIR circuit 511 (LG). TEST the system for normal operation.
  If rear stoplamp, GO to I2.
I2 CHECK CIRCUIT 511 (LG) FOR VOLTAGE
- Disconnect: Multifunction Switch C202a.
- Engage the brake pedal.
- Measure the voltage between multifunction switch C202a-1, circuit 511 (LG), harness side and ground.
  
  Fig 2: Checking Circuit 511 (LG) For Voltage
  Courtesy of FORD MOTOR CO.
- Is the voltage greater than 10 volts?
- Yes : If both rear stoplamps are inoperative, INSTALL a new multifunction switch. REFER to STEERING COLUMN SWITCHES . TEST the system for normal operation.
  If one rear stoplamp is inoperative, GO to I3.
- No : REPAIR the circuit. TEST the system for normal operation.
I3 CHECK THE MULTIFUNCTION SWITCH
- Carry out the multifunction switch component test. Refer to COMPONENT TESTING .
- Is the multifunction switch OK?
- Yes : REPAIR circuit 5 (OG/LB) (RH stoplamp) or 9 (LG/OG) (LH stoplamp) as necessary. TEST the system for normal operation.
- No : INSTALL a new multifunction switch. REFER to STEERING COLUMN SWITCHES . TEST the system for normal operation.