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

E1 CHECK CIRCUIT 57 (BK) FOR AN OPEN
- Disconnect: EATC Module C228a.
- Measure the resistance between EATC module C228a-3, circuit 57 (BK) and ground.
  
  Fig 1: Measuring Resistance Between EATC Module C228A-3, Circuit 57 (BK) And Ground
  Courtesy of FORD MOTOR CO.
- Is the resistance less than 5 ohms?
- Yes : GO to E2.
- No : REPAIR circuit 57 (BK). TEST the system for normal operation.
E2 CHECK CIRCUIT 1566 (RD/YE) FOR B+
- Measure the voltage between EATC module C228a-2, circuit 1566 (RD/YE) and ground.
  
  Fig 2: Measuring Voltage Between EATC Module C228A-2, Circuit 1566 (RD/YE) And Ground
  Courtesy of FORD MOTOR CO.
- Is the voltage reading B+?
- Yes : GO to E3.
- No : REPAIR circuit 1566 (RD/YE). TEST the system for normal operation.
E3 CHECK CIRCUIT 1812 (BN/WH) FOR B+
- Key in ON position.
- Measure the voltage between EATC module C228a-16, circuit 1812 (BN/WH) and ground.
  
  Fig 3: Measuring Voltage Between EATC Module C228A-16, Circuit 1812 (BN/WH) And Ground
  Courtesy of FORD MOTOR CO.
- Is the voltage reading B+?
- Yes : REFER to Module Communication Network Diagnostics in MODULE COMMUNICATIONS NETWORK to diagnose the network concern.
- No : REPAIR circuit 1812 (BN/WH). TEST the system for normal operation.