Pinpoint Test F: No Communication With The Dual Automatic Temperature Control (DATC) Module

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

F1 CHECK CIRCUIT 729 (RD/WH) FOR AN OPEN
- Key in OFF position.
- Disconnect: DATC Module C228b.
- Measure the voltage between the DATC module C228b-13, circuit 729 (RD/WH) and ground.
  
  Fig 1: Measuring Voltage Between DATC Module C228b-13, Circuit 729 (RD/WH) And Ground
  Courtesy of FORD MOTOR CO.
- Is the voltage greater than 10 volts?
- Yes : GO to F2.
- No : REPAIR circuit 729 (RD/WH). TEST the system for normal operation.
F2 CHECK CIRCUIT 1050 (LG/VT) FOR AN OPEN
- Key in ON position.
- Measure the voltage between the DATC module C228b-3, circuit 1050 (LG/VT) and ground.
  
  Fig 2: Measuring Voltage Between DATC Module C228b-3, Circuit 1050 (LG/VT) And Ground
  Courtesy of FORD MOTOR CO.
- Is the voltage greater than 10 volts?
- Yes : GO to F3.
- No : REPAIR circuit 1050 (LG/VT). TEST the system for normal operation.
F3 CHECK CIRCUIT 1203 (BK/LB) FOR AN OPEN
- Key in OFF position.
- Measure the resistance between the DATC module C228b-2, circuit 1203 (BK/LB) and ground.
  
  Fig 3: Measuring Resistance Between DATC Module C228b-2, Circuit 1203 (BK/LB) And Ground
  Courtesy of FORD MOTOR CO.
- Is the resistance less than 5 ohms?
- Yes : GO to MODULE COMMUNICATIONS NETWORK to diagnose the network concern.
- No : REPAIR circuit 1203 (BK/LB). TEST the system for normal operation.