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

F1 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: Measuring Resistance Between EATC Module C228A-1, Circuit 1203 (BK/LB) And Ground
  Courtesy of FORD MOTOR CO.
- Is the resistance less than 5 ohms?
- Yes : GO to F2.
- No : REPAIR circuit 1203 (BK/LB). TEST the system for normal operation.
F2 CHECK CIRCUITS 483 (RD) AND 1566 (RD/YE) FOR AN OPEN
- Key in ON position.
- Measure the voltage between the EATC module C228a-26, circuit 483 (RD), C228a-14, circuit 1566 (RD/YE) and ground.
  
  Fig 2: Measuring Voltage Between EATC Module C228A-26, Circuit 483 (RD), C228A-14, Circuit 1566 (RD/YE) And Ground
  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 483 (RD) or 1566 (RD/YE) for an open. TEST the system for normal operation.