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Home >> Ford >> 2012 >> Mustang Base, 2D Coupe, Automatic Trans >> Repair and Diagnosis >> External Pages >> Different car >> Section 434 (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 Mustang. 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 SBB24 (VT/RD), harness side and ground.
      Fig 1: Measuring Voltage Between Stoplamp Switch C278-1, Circuit SBB24 (VT/RD) And Ground
      G06099159Courtesy of FORD MOTOR CO.
    • Is the voltage greater than 11 volts? 
    • Yes  : GO to I2.
    • No  : VERIFY the BJB fuse 24 (10A) is OK. If OK, REPAIR circuit SBB24 (VT/RD) for an open. If not OK, REFER to the OEM 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 SBB24 (VT/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 SBB24 (VT/RD) And Stoplamp Switch C278-4, Circuit CCB08 (VT/WH)
      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  : REMOVE the jumper wire. GO to I3.
  3. I3 CHECK FOR VOLTAGE TO THE BCM-B 
    • Connect: Stoplamp Switch C278.
    • Disconnect: BCM-B C4368a.
    • While applying the brake pedal, measure the voltage between the BCM-B C4368a-19, circuit CCB08 (VT/WH), harness side and ground.
      Fig 3: Measuring Voltage Between BCM-B C4368A-19, Circuit CCB08 (VT/WH) And Ground
      G06403759Courtesy of FORD MOTOR CO.
    • Is the voltage greater than 11 volts? 
    • Yes  : GO to I4.
    • No  : REPAIR circuit CCB08 (VT/WH) for an open. TEST the system for normal operation.
  4. I4 CHECK FOR CORRECT BCM-B OPERATION 
    • Disconnect all the BCM-B connectors.
    • Check for:
      • corrosion
      • damaged pins
      • pushed-out pins
    • Connect all the BCM-B 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-B. 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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