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Home >> Ford >> 2002 >> Taurus SES, 3.0 S >> Repair and Diagnosis >> External Pages >> Different car >> Section 2479 (Exterior Lighting System) >> Diagnostic Tests >> Trailer Lamps >> Pinpoint Tests >> Pinpoint Test S: The Trailer Lamps Are Inoperative - Trailer Stop/Turn Lamp >> Pinpoint Test S: The Trailer Lamps Are Inoperative - Trailer Stop/Turn Lamp

Pinpoint Test S: The Trailer Lamps Are Inoperative - Trailer Stop/Turn Lamp

WARNING: This page is about a different car, the 2008 Ford RV Cutaway, 2008 Ford Econoline, 2008 Ford E450 Super Duty, and 2008 Ford Cutaway. 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. S1 VERIFY WHICH TRAILER STOP/TURN LAMP IS INOPERATIVE 
    • Apply the brake pedal while observing the trailer lamps.
    • Are both trailer stop/turn lamps inoperative? 
    1. YES  : Go to Pinpoint Test R .
    2. NO  : If both LH and RH trailer stop/turn lamps are inoperative, VERIFY the BJB fuse 26 (20A) is OK. If OK, REPAIR circuit 212 (DB) for an open. TEST the system for normal operation.

      For an inoperative LH trailer lamp, go to  S2.

      For an inoperative RH trailer lamp, go to  S3.

  2. S2 CHECK CIRCUIT 52 (YE) FOR VOLTAGE TO THE TRAILER TOW CONNECTOR 
    • Disconnect the trailer from the vehicle.
    • Key in OFF position.
      • Fig 1: Checking Circuit 52 (YE) For Voltage To Trailer Tow Connector - 4-Pin LH Trailer Stop/Turn Lamp
      GF0032303Courtesy of FORD MOTOR CO.
    • For the 4-pin LH trailer stop/turn lamp, while applying the brake pedal, measure the voltage between the trailer tow C4098-3, circuit 52 (YE), harness side and ground.
      • Fig 2: Checking Circuit 52 (YE) For Voltage To Trailer Tow Connector - 7-Pin LH Trailer Stop/Turn Lamp
      GF0041141Courtesy of FORD MOTOR CO.
    • For the 7-pin LH trailer stop/turn lamp, while applying the brake pedal, measure the voltage between the trailer tow C4099-1, circuit 52 (YE), harness side and ground.
    • Is the voltage greater than 10 volts? 
    1. YES  : The vehicle is operating correctly. SEND the trailer to an authorized camper/trailer repair facility.
    2. NO  : Go to  S4.
  3. S3 CHECK CIRCUIT 64 (DG) FOR VOLTAGE TO THE TRAILER TOW CONNECTOR 
      Fig 3: Checking Circuit 64 (DG) For Voltage To Trailer Tow Connector - 4-Pin RH Trailer Stop/Turn Lamp
      GF0032304Courtesy of FORD MOTOR CO.
    • For the 4-pin RH trailer stop/turn lamp, while applying the brake pedal, measure the voltage between the trailer tow C4098-4, circuit 64 (DG), harness side and ground.
      • Fig 4: Checking Circuit 64 (DG) For Voltage To Trailer Tow Connector - 7-Pin RH Trailer Stop/Turn Lamp
      GF0041143Courtesy of FORD MOTOR CO.
    • For the 7-pin RH trailer stop/turn lamp, while applying the brake pedal, measure the voltage between the trailer tow C4099-4, circuit 64 (DG), harness side and ground.
    • Is the voltage greater than 10 volts? 
    1. YES  : The vehicle is operating correctly. SEND the trailer to an authorized camper/trailer repair facility.
    2. NO  : Go to  S4.
  4. S4 CHECK THE TRAILER TOW TURN RELAY 
    • Disconnect: Suspect Trailer Tow Stop/Turn Relay
    • Substitute a know good relay and recheck the trailer stop/turn lamp operation.
    • Does the trailer stop/turn lamp operate correctly? 
    1. YES  : REMOVE the known good relay. INSTALL a new trailer tow stop/turn relay for the one in question. TEST the system for normal operation.
    2. NO  : REMOVE the known good relay. Go to  S5.
  5. S5 CHECK CIRCUIT 212 (DB) FOR AN OPEN 
      Fig 5: Checking Circuit 212 (DB) For An Open
      GF0012890Courtesy of FORD MOTOR CO.
    • Measure the voltage between the trailer tow LH stop/turn relay pin 3, circuit 212 (DB), relay box face side and ground; or between the trailer tow RH stop/turn relay pin 3, circuit 212 (DB), relay box face side and ground.
    • Is the voltage greater than 10 volts? 
    1. YES  : Go to  S6.
    2. NO  : REPAIR the circuit. TEST the system for normal operation.
  6. S6 CHECK CIRCUIT 57 (BK) FOR AN OPEN 
      Fig 6: Checking Circuit 57 (BK) For An Open
      GF0012891Courtesy of FORD MOTOR CO.
    • Measure the resistance between the trailer tow LH stop/turn relay pin 1, circuit 57 (BK), relay box face side and ground; or between the trailer tow RH stop/turn relay pin 1, circuit 57 (BK), relay box face side and ground.
    • Is the resistance less than 5 ohms? 
    1. YES  : Go to  S7.
    2. NO  : REPAIR the circuit. TEST the system for normal operation.
  7. S7 CHECK FOR VOLTAGE TO THE TRAILER STOP/TURN RELAY 
      Fig 7: Checking For Voltage To Trailer Stop/Turn Relay
      GF0012892Courtesy of FORD MOTOR CO.
    • While applying the brake pedal, measure the voltage between the trailer tow LH stop/turn relay pin 2, circuit 9 (LG/OG), relay box face side and ground; or between the trailer tow RH stop/turn relay pin 2, circuit 5 (OG/LB), relay box face side and ground.
    • Is the voltage greater than 10 volts? 
    1. YES  : REPAIR circuit 64 (DG) (RH stop/turn lamps) or circuit 52 (YE) (LH stop/turn lamps) for an open. TEST the system for normal operation.
    2. NO  : REPAIR circuit 5 (OG/LB) (RH turn/stoplamp) or circuit 9 (LG/OG) (LH turn/stoplamp). TEST the system for normal operation.
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