LEMON Manuals: Even more car manuals for everyone
Home >> Ford >> 2012 >> Mustang Base, 2D Coupe, Automatic Trans >> Repair and Diagnosis >> External Pages >> Different car >> Section 552 (Exterior Lighting System) >> Diagnosis And Testing >> Trailer Lamps >> Pinpoint Tests >> Pinpoint Test Z: The Trailer Parking Lamps Are Inoperative >> Pinpoint Test Z: The Trailer Parking Lamps Are Inoperative

Pinpoint Test Z: The Trailer Parking Lamps Are Inoperative

WARNING: This page is about a different car, the 2014 Ford F-150. 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.
NOTE: Before beginning diagnostics, visually inspect the trailer tow connector for signs of corrosion or damage. Repair or install a new trailer tow connector as required.
  1. Z1 CHECK FOR VOLTAGE THROUGH THE TRAILER TOW CONNECTOR 
    • Ignition OFF.
    • Place the headlamp switch in the PARKING LAMPS ON position.
    • For the 4-pin connector, measure the voltage between the trailer tow C439B-3  , circuit CAT17 (BN), harness side and ground.
      Fig 1: Measuring Voltage Between Trailer Tow C439B-3, Circuit CAT17 (BN) And Ground
      G06099234Courtesy of FORD MOTOR CO.
    • For the 7-pin connector, measure the voltage between the trailer tow connector pin 6, circuit CAT17 (BN), component side and ground.
      Fig 2: Measuring Voltage Between Trailer Tow Connector Pin 6, Circuit CAT17 (BN), Component Side And Ground
      G06133864Courtesy of FORD MOTOR CO.

    Is the voltage greater than 10 volts? 

    • Yes  : The vehicle is operating correctly. SEND the trailer to an authorized camper/trailer repair facility.
    • No  : For the 4-pin connector, GO to  Z3.

      For the 7-pin connector, GO to Z2  .

  2. Z2 CHECK FOR VOLTAGE TO THE TRAILER TOW CONNECTOR (7-PIN) 
    • Disconnect: Trailer Tow C439A  .
    • Measure the voltage between the trailer tow C439A-6  , circuit CAT17 (BN), harness side and ground.
      Fig 3: Measuring Voltage Between Trailer Tow C439A-6, Circuit CAT17 (BN) And Ground
      G06065330Courtesy of FORD MOTOR CO.

    Is the voltage greater than 10 volts? 

    • Yes  : INSTALL a new trailer tow connector. TEST the system for normal operation.
    • No  : GO to Z3  .
  3. Z3 CHECK THE TRAILER TOW PARKING LAMP RELAY 
    • Place the headlamp switch in the OFF position.
    • Disconnect: Trailer Tow Parking Lamp Relay.
    • Substitute a known good relay.
    • Place the headlamp switch in the PARKING LAMPS ON position.
    • For the 4-pin connector, measure the voltage between the trailer tow C439B-3  , circuit CAT17 (BN), harness side and ground.
      Fig 4: Measuring Voltage Between Trailer Tow C439B-3, Circuit CAT17 (BN) And Ground
      G09545946Courtesy of FORD MOTOR CO.
    • For the 7-pin connector, measure the voltage between the trailer tow C439A-6  , circuit CAT17 (BN), harness side and ground.
      Fig 5: Measuring Voltage Between Trailer Tow C439A-6, Circuit CAT17 (BN) And Ground
      G06065330Courtesy of FORD MOTOR CO.

    Is the trailer tow parking lamp relay OK? 

    • Yes  : REMOVE the known good relay. GO to Z4  .
    • No  : REMOVE the known good relay. INSTALL a new trailer tow parking lamp relay. TEST the system for normal operation.
  4. Z4 CHECK FOR VOLTAGE TO THE TRAILER TOW PARKING LAMP RELAY COIL 
    • Measure the voltage between the trailer tow parking lamp relay pin 1, circuit CBP40 (YE/GN), BJB  face side and ground.
      Fig 6: Measuring Voltage Between Trailer Tow Parking Lamp Relay Pin 1, Circuit CBP40 (YE/GN), BJB Face Side And Ground
      G06141879Courtesy of FORD MOTOR CO.

    Is the voltage greater than 10 volts? 

    • Yes  : GO to Z5  .
    • No  : REPAIR circuit CBP40 (YE/GN) for an open. TEST the system for normal operation.
  5. Z5 CHECK THE VOLTAGE SUPPLY CIRCUIT TO THE TRAILER TOW PARKING LAMP RELAY 
    • Place the headlamp switch in the OFF position.
    • Measure the voltage between the trailer tow parking lamp relay pin 3, circuit SBB67 (BU/RD), BJB  face side and ground.
      Fig 7: Measuring Voltage Between Trailer Tow Parking Lamp Relay Pin 3, Circuit SBB67 (BU/RD), BJB Face Side And Ground
      G06141880Courtesy of FORD MOTOR CO.

    Is the voltage greater than 10 volts? 

    • Yes  : GO to Z6  .
    • No  : VERIFY the BJB  fuse 67 (20A) is OK. If OK, REPAIR circuit SBB67 (BU/RD) for an open. TEST the system for normal operation. If not OK, REFER to the OEM WIRING DIAGRAMS to identify the possible causes of the circuit short.
  6. Z6 CHECK THE TRAILER TOW PARKING LAMP RELAY GROUND CIRCUIT FOR AN OPEN 
    • Measure the voltage between the trailer tow parking lamp relay pin 3, circuit SBB67 (BU/RD), BJB  face side and the trailer tow parking lamp relay pin 2, circuit GD123 (BK/GY), BJB  face side.
      Fig 8: Checking Trailer Tow Parking Lamp Relay Ground Circuit For Open
      G06141854Courtesy of FORD MOTOR CO.

    Is the voltage greater than 10 volts? 

    • Yes  : REPAIR circuit CAT17 (BN) for an open. TEST the system for normal operation.
    • No  : REPAIR circuit GD123 (BK/GY) for an open. TEST the system for normal operation.
scientia non olet · About LEMON Manuals