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Home >> Ford >> 2000 >> Contour SE, 2.5 L, Standard >> Repair and Diagnosis >> External Pages >> Different car >> Section 1928 (Exterior Lighting System (F250-F550)) >> Diagnostic Tests >> Trailer Lamps >> Pinpoint Tests >> Pinpoint Test AC: The Trailer Battery Charging Is Inoperative >> Pinpoint Test Ac: The Trailer Battery Charging Is Inoperative

Pinpoint Test Ac: The Trailer Battery Charging Is Inoperative

WARNING: This page is about a different car, the 2007 Ford Pickup, 2007 Ford F550 Super Duty, 2007 Ford F450 Super Duty, and 2007 Ford Cab & Chassis. However, it is still accessible from the selected car via links, so may be relevant.
CAUTION: Use the correct probe adaptor(s) when making measurements. Failure to use the correct probe adaptor(s) may damage the connector.
  1. AC1 CHECK VOLTAGE FOR THE BATTERY CHARGE AT THE TRAILER TOW CONNECTOR 
    • Key in OFF position.
    • Disconnect: Trailer Tow C4099 (7-Pin)
    • Key in ON position.
      • Fig 1: Checking Circuit For Voltage
      GF0004643Courtesy of FORD MOTOR CO.
    • Measure the voltage between the trailer tow C4099-5, circuit 49 (OG) 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  AC2.
  2. AC2 CHECK THE TRAILER TOW BATTERY CHARGE RELAY 
    • Key in OFF position.
    • Disconnect: Trailer Tow Battery Charge Relay C2110
    • Carry out the trailer tow battery charge relay component test. Refer to COMPONENT TESTING article.
    • Is the trailer tow battery charge relay OK? 
    1. YES  : Go to  AC3.
    2. NO  : INSTALL a new trailer tow battery charge relay. TEST the system for normal operation.
  3. AC3 CHECK FOR VOLTAGE TO THE TRAILER TOW BATTERY CHARGE RELAY 
    • Disconnect: Trailer Tow Battery Charge Relay C2110
    • Key in ON position.
      • Fig 2: Checking Circuit For Voltage
      GF0008342Courtesy of FORD MOTOR CO.
    • Measure the voltage between the trailer tow battery charge relay C2110-86, circuit 295 (LB/PK), harness side and ground.
    • Is the voltage greater than 10 volts? 
    1. YES  : Go to  AC5.
    2. NO  : VERIFY the CJB fuse 27 (15A) is OK. If OK, go to  AC4 .
  4. AC4 CHECK CIRCUIT 295 (LB/BK) FOR AN OPEN 
    • Key in OFF position.
    • Disconnect: CJB C270a
      • Fig 3: Checking Circuit For Open
      GF0008343Courtesy of FORD MOTOR CO.
    • Measure the resistance between the CJB C270a-12, circuit 295 (LB/PK), harness side and the CJB C270a-21, circuit 295 (LB/PK), harness side.
    • Is the resistance less than 5 ohms? 
    1. YES  : INSTALL a new CJB. TEST the system for normal operation.
    2. NO  : REPAIR the circuit. TEST the system for normal operation.
  5. AC5 CHECK THE GROUND TO THE TRAILER TOW BATTERY CHARGE RELAY 
    • Key in OFF position.
      • Fig 4: Checking Circuit For Voltage
      GF0008344Courtesy of FORD MOTOR CO.
    • Measure the resistance between the trailer tow battery charge relay C2110-85, circuit 57 (BK), harness side and ground.
    • Is the resistance less than 5 ohms? 
    1. YES  : Go to  AC7.
    2. NO  : Go to  AC6.
  6. AC6 CHECK CIRCUIT 57 (BK) FOR AN OPEN 
    • Disconnect: CJB C270a
      • Fig 5: Checking Circuit For Open
      GF0008345Courtesy of FORD MOTOR CO.
    • Measure the resistance between the CJB C270a-11, circuit 57 (BK), harness side and ground.
    • Is the resistance less than 5 ohms? 
    1. YES  : INSTALL a new CJB. TEST the system for normal operation.
    2. NO  : REPAIR the circuit. TEST the system for normal operation.
  7. AC7 CHECK THE CJB 
      Fig 6: Checking Circuit For Voltage
      GF0008346Courtesy of FORD MOTOR CO.
    • Measure the voltage between the trailer tow battery charge relay C2110-30, harness side and ground.
    • Is the voltage greater than 10 volts? 
    1. YES  : Go to  AC8.
    2. NO  : VERIFY the CJB fuse 107 (20A) is OK. If OK, INSTALL a new CJB. TEST the system for normal operation.
  8. AC8 CHECK CIRCUIT 49 (OG) FOR AN OPEN 
    • Disconnect: CJB C270g
      • Fig 7: Checking Circuit For Open
      GF0008347Courtesy of FORD MOTOR CO.
    • Measure the resistance between the trailer tow C4099-5, circuit 49 (OG), harness side and the CJB C270g-6, circuit 49 (OG), harness side.
    • Is the resistance less than 5 ohms? 
    1. YES  : INSTALL a new CJB. TEST the system for normal operation.
    2. NO  : REPAIR the circuit. TEST the system for normal operation.
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