Pinpoint Test E: The STOPLAMPS Are Inoperative

WARNING: This page is about a different car, the 2005 Ford RV Cutaway, 2005 Ford Econoline, 2005 Ford E450 Super Duty, and 2005 Ford Cutaway. However, it is still accessible from the selected car via links, so may be relevant.

E1 CHECK CIRCUIT 10 (LG/RD) FOR AN OPEN
- Key in OFF position.
- Disconnect: Stoplamp Switch C278.
- Measure the voltage between the stoplamp switch C278 pin 1, circuit 10 (LG/RD), harness side and ground.
  
  Fig 1: Measuring Voltage Between Stoplamp Switch Pin 1 And Ground
  Courtesy of FORD MOTOR CO.
- Is the voltage greater than 10 volts?
- Yes : GO to E2.
- No : REPAIR the circuit. TEST the system for normal operation.
E2 CHECK THE STOPLAMP SWITCH
- Connect a fused (10A) jumper wire between the stoplamp switch C278 pin 2, circuit 10 (LG/RD), harness side and the stoplamp switch C278 pin 1, circuit 569 (DG), harness side.
  
  Fig 2: Connecting Fused Jumper Wire Between Stoplamp Switch Pin 2 And Pin 1
  Courtesy of FORD MOTOR CO.
- Do the stoplamps illuminate?
- Yes : INSTALL a new stoplamp switch. REFER to LAMP SWITCH - BRAKE PEDAL POSITION . TEST the system for normal operation.
- No : LEAVE the jumper wire connected. GO to E3.
E3 CHECK FOR VOLTAGE TO THE CJB FUSE 39 (10A)
- Measure the voltage between the CJB fuse 39 and ground.
  
  Fig 3: Measuring Voltage Between CJB Fuse 39 And Ground
  Courtesy of FORD MOTOR CO.
- Is the voltage greater than 10 volts?
- Yes : REPAIR circuit 511 (LG). TEST the system for normal operation.
- No : REPAIR circuit 569 (DG). TEST the system for normal operation.