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Home >> Ford >> 2012 >> Mustang Base, 2D Coupe, Automatic Trans >> Repair and Diagnosis >> External Pages >> Different car >> Section 343 (Exterior Lighting System) >> Diagnosis And Testing >> Stoplamps >> Pinpoint Tests >> Pinpoint Test I: All The Stoplamps Are Inoperative >> Pinpoint Test I: All The STOPLAMPS Are Inoperative

Pinpoint Test I: All The STOPLAMPS Are Inoperative

WARNING: This page is about a different car, the 2013 Ford F-550 Super Duty, 2013 Ford F-450 Super Duty, 2013 Ford F-350 Super Duty, and 2013 Ford F-250 Super Duty. However, it is still accessible from the selected car via links, so may be relevant.
NOTE: Use the correct probe adapter(s) when making measurements. Failure to use the correct probe adapter(s) may damage the connector.
  1. I1 CHECK FOR VOLTAGE TO THE STOPLAMP SWITCH 
    • Ignition OFF.
    • Disconnect: Stoplamp Switch C278.
    • Measure the voltage between the stoplamp switch C278-1, circuit SBP21 (GY/RD), harness side and ground.
      Fig 1: Measuring Voltage Between Stoplamp Switch C278-1, Circuit SBP21 (GY/RD) And Ground
      G06099159Courtesy of FORD MOTOR CO.
    • Is the voltage greater than 10 volts? 
    • Yes  : GO to I2.
    • No  : VERIFY the BCM fuse 21 (10A) is OK. If OK, GO to  I4. If not OK, REFER to the SYSTEM WIRING DIAGRAMS to identify the possible causes of the circuit short.
  2. I2 BYPASS THE STOPLAMP SWITCH 
    • Connect a fused jumper wire between the stoplamp switch C278-1, circuit SBP21 (GY/RD), harness side and the stoplamp switch C278-4, circuit CCB08 (VT/WH), harness side.
      Fig 2: Connecting Fused Jumper Wire Between Stoplamp Switch C278-1, Circuit SBP21 (GY/RD) And Stoplamp Switch C278-4, Circuit CCB08 (VT/WH), Harness Side
      G06099160Courtesy of FORD MOTOR CO.
    • Are the stoplamps illuminated? 
    • Yes  : REMOVE the jumper wire. INSTALL a new stoplamp switch. REFER to STOPLAMP SWITCH .

      TEST the system for normal operation.

    • No  : LEAVE the jumper wire connected. GO to I3.
  3. I3 CHECK THE STOPLAMP SWITCH SIGNAL TO THE BCM 
    • Disconnect: BCM C2280b.
    • Measure the voltage between the BCM C2280b-28, circuit CCB08 (VT/WH), harness side and ground.
      Fig 3: Measuring Voltage Between BCM C2280B-28, Circuit CCB08 (VT/WH) And Ground
      G07399328Courtesy of FORD MOTOR CO.
    • Is the voltage greater than 10 volts? 
    • Yes  : REMOVE the jumper wire. GO to  I5.
    • No  : REMOVE the jumper wire. REPAIR circuit CCB08 (VT/WH) for an open. TEST the system for normal operation.
  4. I4 CHECK THE STOPLAMP SWITCH VOLTAGE SUPPLY CIRCUIT FOR AN OPEN 
    • Disconnect: BCM C2280d.
    • Measure the resistance between the stoplamp switch C278-1, circuit SBP21 (GY/RD), harness side and the BCM C2280d-9, circuit SBP21 (GY/RD), harness side.
      Fig 4: Measuring Resistance Between Stoplamp Switch C278-1, Circuit SBP21 (GY/RD) And BCM C2280D-9, Circuit SBP21 (GY/RD)
      G07485048Courtesy of FORD MOTOR CO.
    • Is the resistance less than 5 ohms? 
    • Yes  : GO to I5.
    • No  : REPAIR circuit SBP21 (GY/RD) for an open. TEST the system for normal operation.
  5. I5 CHECK FOR CORRECT BCM OPERATION 
    • Disconnect all the BCM connectors.
    • Check for:
      • corrosion
      • damaged pins
      • pushed-out pins
    • Connect all the BCM 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 BCM. 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.
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