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Home >> Ford >> 2004 >> Mustang Mach 1, Standard >> Repair and Diagnosis (Single Page) >> Electrical >> Gauges >> Instrument Cluster System And Panel Illumination >> Diagnosis And Testing >> Instrument Cluster and Panel Illumination >> Pinpoint Tests >> Pinpoint Test D: The Audio System Illumination Is Inoperative

Pinpoint Test D: The Audio System Illumination Is Inoperative

  1. D1 CHECK VOLTAGE TO AUDIO UNIT 
    • Disconnect: Audio Unit C290a.
    • Place the headlamp switch in the ON position.
    • Rotate the instrument panel dimmer switch to the full illumination position.
    • Measure the voltage between the audio unit C290a pin 1, circuit 19 (LB/RD), harness side and ground.
      Fig 1: Checking Voltage To Audio Unit
      G03242507Courtesy of FORD MOTOR CO.
    • Is the voltage greater than 10 volts? 
    1. Yes:  GO to D2.
    2. No:  REPAIR the circuit. TEST the system for normal operation.
  2. D2 CHECK GROUND TO AUDIO UNIT 
    • Measure the resistance between the audio unit C290a pin 2, circuit 1205 (BK), harness side and ground.
      Fig 2: Checking Ground To Audio Unit
      G03242508Courtesy of FORD MOTOR CO.
    • Is the resistance less than 5 ohms? 
    1. Yes:  REMOVE the audio unit and SEND it to an authorized Ford audio systems repair facility. TEST the system for normal operation.
    2. No:  REPAIR the circuit. TEST the system for normal operation.
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