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

WARNING: This page is about a different car, the 2007 Lincoln Mark LT and 2007 Ford Pickup. However, it is still accessible from the selected car via links, so may be relevant.
CAUTION: Use the correct probe adapter(s) when making measurements. Failure to use the correct probe adapter(s) may damage the connector.
  1. D1 CHECK THE EATC MODULE VOLTAGE SUPPLY CIRCUITS FOR AN OPEN 
    • Key in OFF position.
    • Disconnect: EATC Module C228a
    • Key in ON position.
    • Measure the voltage between the EATC module, harness side and ground as follows:
      Connector-Pin Circuit
      C228a-14 296 (WH/VT)
      C228a-26 729 (RD/WH)
    • Are the voltages greater than 10 volts? 
    1. YES  : Go to  D2.
    2. NO  : VERIFY the central junction box (CJB) fuse 5 (7.5A) or 13 (10A) are OK. If OK, REPAIR the circuit in question. CLEAR the DTCs. REPEAT the network test with the scan tool.
  2. D2 CHECK THE EATC MODULE GROUND CIRCUIT 875 (BK/LB) FOR AN OPEN 
    • Key in OFF position.
    • Measure the resistance between the EATC module C228a-1, circuit 875 (BK/LB) and ground.
      • Fig 1: Checking EATC Module Ground Circuit 875 (BK/LB) For An Open
      GF0004704Courtesy of FORD MOTOR CO.
    • Is the resistance less than 5 ohms? 
    1. YES  : Go to  D3.
    2. NO  : REPAIR the circuit. CLEAR the DTCs. REPEAT the network test with the scan tool.
  3. D3 CHECK THE UBP NETWORK CIRCUIT 1906 (VT) BETWEEN THE DATA LINK CONNECTOR (DLC) AND THE EATC MODULE FOR AN OPEN 
    • Disconnect: EATC Module C228b
    • Measure the resistance between the EATC module C228b-12, circuit 1906 (VT), harness side and the DLC C251-3, harness side.
      • Fig 2: Checking UBP Network Circuit 1906 (VT) Between Data Link Connector (DLC) And EATC Module For An Open
      GF0004705Courtesy of FORD MOTOR CO.
    • Is the resistance less than 5 ohms? 
    1. YES  : Go to  D4.
    2. NO  : REPAIR the circuit. CLEAR the DTCs. REPEAT the network test with the scan tool.
  4. D4 CHECK FOR CORRECT EATC MODULE OPERATION 
    • Disconnect all the EATC module connectors.
    • Check for:
      • corrosion
      • damaged pins
      • pushed-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? 
    1. YES  : INSTALL a new EATC module. REFER to CLIMATE CONTROL article. CLEAR the DTCs. REPEAT the network test with the scan tool.
    2. NO  : The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector. CLEAR the DTCs. REPEAT the network test with the scan tool.
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