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Home >> Ford >> 2000 >> Taurus LX, 3.0 2, AX4N >> Repair and Diagnosis >> External Pages >> Different car >> Section 881 (Exterior Lighting System) >> Diagnostic Tests >> Stoplamps >> Pinpoint Tests >> Pinpoint Test I: The Stoplamps Are Inoperative >> Pinpoint Test I: The STOPLAMPS Are Inoperative

Pinpoint Test I: The STOPLAMPS Are Inoperative

WARNING: This page is about a different car, the 2007 Lincoln Mark LT and 2007 Ford Pickup. However, it is still accessible from the selected car via links, so may be relevant.
CAUTION: Use the correct probe adapter(s) when making measurements. Failure to use the correct probe adapter(s) may damage the connector.
  1. I1 CHECK THE VOLTAGE TO THE STOPLAMP SWITCH 
    • Key in OFF position.
    • Disconnect: Stoplamp Switch C278
    • Measure the voltage between the stoplamp switch C278-1, circuit 10 (LG/RD), harness side and ground.
      • Fig 1: Checking Voltage To Stoplamp Switch
      GF0004592Courtesy of FORD MOTOR CO.
    • Is the voltage greater than 10 volts? 
    1. YES  : Go to  I3.
    2. NO  : VERIFY the CJB fuse 2 (20A) is OK. If OK, go to  I2 .
  2. I2 CHECK CIRCUIT 10 (LG/RD) FOR AN OPEN 
    • Disconnect: CJB C270f
    • Measure the resistance between the CJB C270f-3, circuit 10 (LG/RD), harness side and the stoplamp switch C278-1, circuit 10 (LG/RD), harness side.
      • Fig 2: Checking Circuit 10 (LG/RD) For An Open
      GF0004593Courtesy of FORD MOTOR CO.
    • Is the resistance less than 5 ohms? 
    1. YES  : REPAIR or INSTALL a new CJB. TEST the system for normal operation.
    2. NO  : REPAIR the circuit. TEST the system for normal operation.
  3. I3 CHECK THE STOPLAMP SWITCH OPERATION 
    • Connect a fused (20A) jumper wire between the stoplamp switch C278-1, circuit 10 (LG/RD), harness side and the stoplamp switch C278-2, circuit 511 (LG), harness side.
      • Fig 3: Checking Stoplamp Switch Operation
      GF0004594Courtesy of FORD MOTOR CO.
    • Do the stoplamps illuminate? 
    1. YES  : INSTALL a new stoplamp switch. REFER to Stoplamp Switch  in this article. TEST the system for normal operation.
    2. NO  : REPAIR circuit 511 (LG). TEST the system for normal operation.
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