Pinpoint Test E: No Communication With The Electronic Automatic Temperature Control (EATC) Module

WARNING: This page is about a different car, the 2004 Mercury Monterey and 2004 Ford Freestar. However, it is still accessible from the selected car via links, so may be relevant.

E1 CHECK CIRCUIT 1203 (BK/LB) FOR AN OPEN
- Key in OFF position.
- Disconnect: EATC Module C228a.
- Measure the resistance between the EATC module C228a-1, circuit 1203 (BK/LB) and ground.
  
  Fig 1: Checking Circuit 1203 (BK/LB) For An Open
  Courtesy of FORD MOTOR CO.
- Is the resistance less than 5 ohms?
Yes

GO to E2.

No

REPAIR circuit 1203 (BK/LB). TEST the system for normal operation.
E2 CHECK CIRCUITS 1001 (WH/YE) AND 1003 (GY/YE) FOR AN OPEN
- Key in ON position.
- Measure the voltage between the EATC module C228a-26, circuit 1001 (WH/YE), C228a-14, circuit 1003 (GY/YE) and ground.
  
  Fig 2: Checking Circuits 1001 (WH/YE) And 1003 (GY/YE) For An Open
  Courtesy of FORD MOTOR CO.
- Is the voltage greater than 10 volts?
Yes

GO to MODULE COMMUNICATIONS NETWORK to diagnose the network concern.

No

REPAIR circuit 1001 (WH/YE) or 1003 (GY/YE) for an open. TEST the system for normal operation.