Pinpoint Test A: No Communication With The Audio Unit

WARNING: This page is about a different car, the 2006 Mercury Milan, 2006 Lincoln Zephyr, and 2006 Ford Fusion. However, it is still accessible from the selected car via links, so may be relevant.

CAUTION: For vehicles built through 8/2005, whenever power is disconnected (through the battery or through disconnecting the connector) from the CD6 audio unit, then reconnected, the power must be continuous for a minimum of 25 seconds. Failure to follow this instruction may result in permanent damage to the audio unit.

A1 CHECK CIRCUITS SBP11 (BU/RD) AND CBP02 (GN) FOR VOLTAGE
- Key in OFF position.
- Disconnect: Audio Unit C290a or C240a.
- Key in ON position.
- Measure the voltage between the audio unit C290a-1 or C240a-1, circuit SBP11 (BU/RD), harness side and ground; and between the audio unit C290a-2 or C240a-2, circuit CBP02 (GN), harness side and ground.
  
  Fig 1: Checking Circuits SBP11 (BU/RD) And CBP02 (GN) 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 12 (7.5A) or fuse 18 (20A) is OK. If OK, REPAIR the circuit in question. TEST the system for normal operation.
A2 CHECK CIRCUIT GD114 (BK/BU) FOR AN OPEN
- Key in OFF position.
- Measure the resistance between the audio unit C290a-13 or C240a-13, circuit GD114 (BK/BU), harness side and ground.
  
  Fig 2: Checking Circuit GD114 (BK/BU) For Open
  Courtesy of FORD MOTOR CO.
- Is the resistance less than 5 ohms?
Yes : REFER to MODULE COMMUNICATIONS NETWORK to continue diagnosis of the communication network.

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