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

WARNING: This page is about a different car, the 2005 Mercury Sable and 2005 Ford Taurus. However, it is still accessible from the selected car via links, so may be relevant.

B1 CHECK EATC MODULE C228 FOR DAMAGE
- Key in OFF position.
- Disconnect: EATC Module C228.
- Inspect the EATC module C228 for damage.
- Is the EATC module C228 OK?
- Yes : GO to B2.
- No : REPAIR the EATC module C228. CARRY OUT the diagnostic tool data link test.
B2 CHECK MEDIUM SPEED CAN CIRCUITS 1827 (WH/LG) AND 1828 (PK/LG) BETWEEN DLC C251 AND EATC MODULE C228 FOR OPEN
- Measure the resistance between the EATC module C228 pin 7, circuit 1827 (WH/LG), harness side and the DLC C251 pin 3, circuit 1827 (WH/LG), harness side; and between the EATC module C228 pin 8, circuit 1828 (PK/LG), harness side and the DLC C251 pin 11, circuit 1828 (PK/LG), harness side.
  
  Fig 1: Checking Medium Speed CAN Circuits 1827 (WH/LG) And 1828 (PK/LG) Between DLC C251 And EATC Module C228 For Open
  Courtesy of FORD MOTOR CO.
- Are the resistances less than 5 ohms?
- Yes : GO to B3.
- No : REPAIR the circuit in question. CLEAR the DTCs. REPEAT the self-test. CARRY OUT the diagnostic tool data link test.
B3 CHECK FOR CORRECT EATC MODULE OPERATION
- Disconnect all the EATC module connectors.
- Check for:
  - corrosion
  - 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?
- Yes : INSTALL a new EATC module. REFER to CLIMATE CONTROL SYSTEM-GENERAL INFORMATION . CLEAR the DTCs. REPEAT the self-test. CARRY OUT the diagnostic tool data link 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 diagnostic tool data link test.