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Test C: Transmission Control Module (TCM) Does Not Respond To NGS

  1. Turn ignition off. Disconnect TCM connector is located behind instrument cluster. Inspect connector for loose, damaged or corroded terminals. Repair connector as necessary and retest system for normal operation. If connector is okay, measure resistance of Yellow/Red wire between terminal No. 6 at TCM connector C277B and terminal No. 1 at Data Link Connector (DLC) C252. See Figure and Fig 1 . If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, go to step  3.
  2. Measure resistance of Yellow/Red wire between male side of in-line connector C255 terminal No. 4 and DLC C252 terminal No. 1. In-line connector C255 is located behind instrument cluster. See Fig 2. If resistance is less than 5 ohms, repair open Yellow/Red wire between TCM connector C277B and in-line connector C255. Retest system. If resistance is 5 ohms or more, repair open Yellow/Red wire between in-line connector C255 and DLC C252. Retest system.
  3. Measure resistance of Yellow/Black wire between terminal No. 7 at TCM connector C277B and terminal No. 2 at DLC C252. If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, replace TCM. Retest system.
  4. Measure resistance of Yellow/Black wire between male side of in-line connector C255 terminal No. 9 and DLC C252 terminal No. 2. In-line connector C255 is located behind instrument cluster. See Fig 2. If resistance is less than 5 ohms, repair open Yellow/Black wire between TCM connector C277B and in-line connector C255. Retest system. If resistance is 5 ohms or more, repair open Yellow/Black wire between in-line connector C255 and DLC C252. Retest system.
Fig 1: Identifying Transmission Control Module (TCM) Connector C277B Terminals
G99J02230Courtesy of FORD MOTOR CO.
Fig 2: Identifying Male Side Of In-Line Connector C255 Terminals
G99I08571Courtesy of FORD MOTOR CO.