Pinpoint Test L: Navigation System Will Not Switch On

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

L1 CHECK CIRCUIT 194 (PK) FOR VOLTAGE
- Key in OFF position.
- Disconnect: Audio Unit C2123a.
- Key in ON position.
- Measure the voltage between the audio unit C2123a pin 3, circuit 194 (PK), harness side and ground.
  
  Fig 1: Measuring Voltage Between Audio Unit C2123A Pin 3 Circuit 194 (PK)
  Courtesy of FORD MOTOR CO.
- Is the voltage greater than 10 volts?
- Yes : GO to L2.
- No : REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test.
L2 CHECK CIRCUIT 1000 (RD/BK) FOR VOLTAGE
- Key in OFF position.
- Disconnect: Audio Unit C2123c.
- Key in START position.
- Measure the voltage between the audio unit C2123c pin 7, circuit 1000 (RD/BK), harness side and ground.
  
  Fig 2: Measuring Voltage Between Audio Unit C2123C Pin 7 Circuit 1000 (RD/BK)
  Courtesy of FORD MOTOR CO.
- Is the voltage greater than 10 volts?
- Yes : GO to L3.
- No : REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test.
L3 CHECK CIRCUIT 797 (LG/VT) FOR VOLTAGE
- Measure the voltage between the audio unit C2123a pin 1, circuit 797 (LG/VT), harness side and ground.
  
  Fig 3: Measuring Voltage Between Audio Unit C2123A Pin 1 Circuit 797 (LG/VT)
  Courtesy of FORD MOTOR CO.
- Is the voltage greater than 10 volts?
- Yes : GO to L4.
- No : REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test.
L4 CHECK CIRCUIT 694 (BK/LG) FOR AN OPEN
- Key in OFF position.
- Measure the resistance between the audio unit C2123a pin 6, circuit 694 (BK/LG), harness side and ground.
  
  Fig 4: Measuring Resistance Between Audio Unit C2123A Pin 6 Circuit 694 (BK/LG)
  Courtesy of FORD MOTOR CO.
- Is the resistance less than 5 ohms?
- Yes : GO to L5.
- No : REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test.
L5 CHECK FOR CORRECT AUDIO UNIT OPERATION
- Disconnect all the audio unit connectors.
- Check for:
  - corrosion
  - pushed-out pins
- Connect all the audio unit connectors and make sure they seat correctly.
- Operate the system and verify the concern is still present.
- Is the concern still present?
- Yes : REMOVE the audio unit and SEND it to an authorized audio system repair facility. REFER to AUDIO UNIT . CLEAR the DTCs. REPEAT the self-test.
- No : The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector. CLEAR the DTCs. REPEAT the self-test.