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

WARNING: This page is about a different car, the 2005 Ford Pickup, 2005 Ford F550 Super Duty, 2005 Ford F450 Super Duty, and 2005 Ford Cab & Chassis. However, it is still accessible from the selected car via links, so may be relevant.

E1 CHECK CIRCUIT 676 (PK/OG) FOR AN OPEN
- Key in OFF position.
- Disconnect: EATC Module C228a.
- Measure the resistance between the EATC module C228a pin 2, circuit 676 (PK/OG) and ground.
  
  Fig 1: Checking Circuit 676 (PK/OG) For An Open
  Courtesy of FORD MOTOR CO.
- Is the resistance less than 25 ohms?
- Yes : GO to E2.
- No : REPAIR circuit 676 (PK/OG) for an open. TEST the system for normal operation.
E2 CHECK CIRCUIT 22 (LB/BK) FOR B+
- Disconnect: EATC module C228b.
- Measure the voltage between the EATC module C228b pin 11, circuit 22 (LB/BK) and ground.
  
  Fig 2: Checking Circuit 22 (LB/BK) For B+
  Courtesy of FORD MOTOR CO.
- Is the voltage B+?
- Yes : GO to E3.
- No : REPAIR circuit 22 (LB/BK) for an open. TEST the system for normal operation.
E3 CHECK CIRCUIT 296 (WH/VT) FOR B+
- Key in ON position.
- Measure the voltage between the EATC module C228b pin 22, circuit 296 (WH/VT) and ground.
  
  Fig 3: Checking Circuit 296 (WH/VT) For B+
  Courtesy of FORD MOTOR CO.
- Is the voltage B+?
- Yes : REFER to MODULE COMMUNICATIONS NETWORK to diagnose a network concern.
- No : REPAIR circuit 296 (WH/VT) for an open. TEST the system for normal operation.