Pinpoint Test H: No Communication With The Dual Automatic Temperature Control Module

WARNING: This page is about a different car, the 2005 Lincoln Town Car. However, it is still accessible from the selected car via links, so may be relevant.

H1 CHECK CIRCUIT 676 (PK/OG) FOR AN OPEN
- Key in OFF position.
- Disconnect: DATC Module C228a.
- Measure the resistance between the DATC module C228a-2, circuit 676 (PK/OG) and ground.
  
  Fig 1: Measuring Resistance Between DATC Module C228a-2, Circuit 676 (PK/OG) And Ground
  Courtesy of FORD MOTOR CO.
- Is the resistance less than 5 ohms?
- Yes : GO to H2.
- No : REPAIR circuit 676 (PK/OG) for an open. TEST the system for normal operation.
H2 CHECK CIRCUIT 729 (RD/WH) FOR B+
- Disconnect: DATC module C228b.
- Measure the voltage between the DATC module C228b-11, circuit 729 (RD/WH) and ground.
  
  Fig 2: Measuring Voltage Between DATC Module C228b-11, Circuit 729 (RD/WH) And Ground
  Courtesy of FORD MOTOR CO.
- Is the voltage B+?
- Yes : GO to H3.
- No : REPAIR circuit 729 (RD/WH) for an open. TEST the system for normal operation.
H3 CHECK CIRCUIT 1040 (RD/BK) FOR B+
- Key in ON position.
- Measure the voltage between the DATC module C228b-22, circuit 1040 (RD/BK) and ground.
  
  Fig 3: Measuring Voltage Between DATC Module C228b-22, Circuit 1040 (RD/BK) And Ground
  Courtesy of FORD MOTOR CO.
- Is the voltage B+?
- Yes : REFER to MODULE COMMUNICATIONS NETWORK to diagnose a network concern.
- No : REPAIR circuit 1040 (RD/BK) for an open. TEST the system for normal operation.