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Home >> Ford >> 2003 >> Excursion 7.3 F, RWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 1765 (Auxiliary Brake System) >> Diagnostic Tests >> Auxiliary Brake System - Trailer Brake Control (TBC) Module >> Pinpoint Tests >> Pinpoint Test E: The TBC Module LED Display Does Not Illuminate And The Trailer Brakes Are Inoperative >> Pinpoint Test E: The TBC Module Led Display Does Not Illuminate And The Trailer Brakes Are Inoperative
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Pinpoint Test E: The TBC Module Led Display Does Not Illuminate And The Trailer Brakes Are 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 flex probe kit for all test connections to prevent damage to the wiring terminals. Do not use standard multimeter probes.
NOTE: Make sure the trailer brakes are electric-magnet actuated drum type brakes before proceeding with this pinpoint test.
  1. E1 CHECK FOR ANY ANTI-LOCK BRAKE SYSTEM (ABS) MODULE DIAGNOSTIC TROUBLE CODES (DTCs) 
    • Key in OFF position.
    • Carry out the ABS module self-test. Retrieve and record any ABS module DTCs.
    • Are any ABS module DTCs retrieved? 
    1. YES  : REFER to VEHICLE DYNAMIC SYSTEMS article to continue diagnosis of the ABS.
    2. NO  : Go to  E2.
  2. E2 CHECK THE VOLTAGE TO THE TBC MODULE 
    • Disconnect: TBC Module C2142a
    • Disconnect: TBC Module C2142b
    • Key in ON position.
    • Measure the voltage between the TBC module, harness side and ground as follows:
      • TBC module C2142a-1, circuit 50 (RD), harness side.
      • TBC module C2142b-3, circuit 298 (VT/OG), harness side.
      • Fig 1: Checking Voltage To TBC Module
      GF0006739Courtesy of FORD MOTOR CO.
    • Are the voltages greater than 10 volts? 
    1. YES  : Go to  E3.
    2. NO  : VERIFY CJB fuse 101 (30A) is OK. If OK, REPAIR circuit 50 (RD).

      VERIFY CJB fuse 28 (10A) is OK. If OK, REPAIR circuit 298 (VT/OG).

      CLEAR the DTCs. REPEAT the self-test.

  3. E3 CHECK CIRCUIT 206 (WH) FOR AN OPEN 
    • Key in OFF position.
    • Measure the resistance between TBC module C2142a-4, circuit 206 (WH), harness side and ground.
      • Fig 2: Checking Ground Circuit 206 (WH) For Open
      GF0006738Courtesy of FORD MOTOR CO.
    • Is the resistance less than 5 ohms? 
    1. YES  : Go to  E4.
    2. NO  : REPAIR circuit 206 (WH). CLEAR the DTCs. REPEAT the self-test.
  4. E4 CHECK CIRCUIT 43 (DB) FOR AN OPEN 
    • Disconnect: Trailer Tow C4099
    • Measure the resistance between trailer tow C4099-3, circuit 43 (DB), harness side and TBC C2142a-3, circuit 43 (DB), harness side.
    • Is the resistance less than 5 ohms? 
      • Fig 3: Checking Circuit 43 (DB) For Open
      GF0006754Courtesy of FORD MOTOR CO.
    1. YES  : Go to  E5.
    2. NO  : REPAIR circuit 43 (DB). CLEAR the DTCs. REPEAT the self-test.
  5. E5 CHECK CIRCUIT 43 (DB) FOR VOLTAGE 
    NOTE: Battery voltage must be greater than 10 volts.
    • Key in OFF position.
    • Connect: TBC Module C2142a
    • Connect: TBC Module C2142b
    • Key in ON position.
    • Have an assistant press the manual slider switch fully to the left with a gain of 10 on the TBC module.
    • Measure the voltage between trailer tow C4099-3, circuit 43 (DB), harness side and ground.
    • Is the voltage greater than 10-12 volts? 
    1. YES  : The TBC module is operating correctly. SEND the trailer to an authorized camper/trailer repair center for an overload condition.
    2. NO  : Go to  E6.
  6. E6 CHECK FOR CORRECT TBC MODULE OPERATION 
    • Disconnect all the TBC module connectors.
    • Check for:
      • corrosion.
      • pushed-out pins.
      • spread terminals.
    • Connect all the TBC module connectors and make sure that they are seated correctly.
    • Operate the system and verify the concern is still present.
    • Is the concern still present? 
    1. YES  : INSTALL a new TBC module. REFER to Trailer Brake Control (TBC) Module  in this article. TEST the system for normal operation.
    2. NO  : The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector. TEST the system for normal operation.
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