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Pinpoint Test J: The Electronic Automatic Temperature Control (EATC) Module Does Not Respond To The Diagnostic Tool

WARNING: This page is about a different car, the 2004 Mercury Mountaineer and 2004 Ford Explorer. However, it is still accessible from the selected car via links, so may be relevant.
  1. J1 CHECK THE EATC MODULE C228b FOR DAMAGE 
    • Key in OFF position.
    • Disconnect: EATC Module C228b.
    • Inspect the EATC module C228b for damage.
    • Is the EATC module C228b OK? 

    Yes 

    GO to J2.

    No 

    REPAIR the EATC module C228b. CARRY OUT the data link diagnostics test.

  2. J2 CHECK CIRCUITS 3125 (RD/YE) AND 3126 (TN/YE) FOR AN OPEN 
    • Measure the resistance between the EATC module C228b-11, circuit 3126 (TN/YE), harness side and the DLC C251-6, circuit 3126 (TN/YE), harness side.
      Fig 1: Measuring in Between EATC Module C228B-11, Circuit 3126 (TN/YE) Harness Side And DLC C251-6, Circuit 3126 (TN/YE), Harness Side
      G03183441Courtesy of FORD MOTOR CO.
    • Measure the resistance between the EATC module C228b-1 circuit 3125 (RD/YE), harness side and the DLC C251-14, circuit 3125 (RD/YE), harness side.
      Fig 2: Measuring Resistance Between EATC Module C228B-1 Circuit 3125 (RD/YE), Harness Side And DLC C251-14, Circuit 3125 (RD/YE), Harness Side
      G03183442Courtesy of FORD MOTOR CO.
    • Are the resistances less than 5 ohms? 

    Yes 

    GO to J3.

    No 

    REPAIR the circuit in question. CLEAR the DTCs. REPEAT the self-test. CARRY OUT the data link diagnostics test.

  3. J3 CHECK FOR CORRECT EATC MODULE OPERATION 
    • Disconnect all the EATC module connectors.
    • Check for:
      • corrosion
      • push-out pins
    • Connect all the EATC module connectors and make sure they seat correctly.
    • Operate the system and verify the concern is still present.
    • Is the concern still present? 

    Yes 

    INSTALL a new EATC module. REFER to CLIMATE CONTROL SYSTEM . CLEAR the DTCs. REPEAT the self-test. CARRY OUT the data link diagnostics test.

    No 

    The system is operating correctly at this time. Concern may have been caused by a loose or corroded connector. CLEAR the DTCs. REPEAT the self-test. CARRY OUT the data link diagnostics test.