Pinpoint Test A: No Communication With The Audio Unit

WARNING: This page is about a different car, the 2006 Mercury Montego, 2006 Ford Freestyle, and 2006 Ford Five Hundred. However, it is still accessible from the selected car via links, so may be relevant.

A1 CHECK CIRCUITS 1006 (DG/WH) AND 1111 (VT) FOR VOLTAGE
- Key in OFF position.
- Disconnect: Audio Unit C290a.
- Measure the voltage between the audio unit C290a-1, circuit 1111 (VT), harness side and ground; and between the audio unit C290a-2, circuit 1006 (DG/WH), harness side and ground.
  
  Fig 1: Checking Circuits 1006 (DG/WH) & 1111 (VT) For Voltage
  Courtesy of FORD MOTOR CO.
- Are the voltages greater than 10 volts?
Yes : GO to A2.

No : VERIFY the smart junction box (SJB) fuse 11 (20A) or fuse 15 (10A) is OK. If OK, repair the circuit in question. TEST the system for normal operation.
A2 CHECK CIRCUIT 1204 (BK/OG) FOR AN OPEN
- Key in OFF position.
- Measure the resistance between the audio unit C240a-13, circuit 1204 (BK/OG), harness side and ground.
  
  Fig 2: Measuring Resistance Between connector And Ground
  Courtesy of FORD MOTOR CO.
- Is the resistance less than 5 ohms?
Yes: REFER to COMMUNICATIONS NETWORK to continue diagnosis of the communication network.

No: REPAIR the circuit. TEST the system for normal operation.