PINPOINT TEST A: NO COMMUNICATION WITH THE AUDIO UNIT-CDX6 AND DM1 00i ONLY

WARNING: This page is about a different car, the 2004 Lincoln LS. However, it is still accessible from the selected car via links, so may be relevant.

A1 CHECK THE VOLTAGE TO THE AUDIO UNIT
- Key in OFF position.
- Disconnect: Audio Unit C290b.
- Key in ON position.
- Measure the voltage between the audio unit C290b-1, circuit 29-MD15 (OG/BK), harness side and ground; and between the audio unit C290b-2, circuit 75-MD15 (YE/GN), harness side and ground.
  
  Fig 1: Checking Voltage To Audio Unit
  Courtesy of FORD MOTOR CO.
- Are the voltages greater than 10 volts?
1. Yes : GO to A2.
2. No : REPAIR the circuit in question. REPEAT the data link diagnostic test.
A2 CHECK THE GROUND TO THE AUDIO UNIT
- Key in OFF position.
- Measure the resistance between the audio unit C290b-13, circuit 31 -MD15 (BK/GN), harness side and ground.
  
  Fig 2: Measuring Resistance Between Audio Unit C290B-13, Circuit 31 -MD15 (BK/GN), Harness Side And Ground
  Courtesy of FORD MOTOR CO.
- Is the resistance less than 5 ohms?
1. Yes : REFER to MODULE COMMUNICATIONS NETWORK to continue diagnosis of the audio unit.
2. No : REPAIR the circuit in question. REPEAT the data link diagnostic test.