Pinpoint Test A: No Communication With The Navigation System Module

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.

A1 CHECK CIRCUITS 720 (RD/YE) AND 194 (PK) FOR VOLTAGE
- Key in OFF position.
- Disconnect: Navigation System Module C2279a.
- Key in ON position.
- Measure the voltage between the navigation system module C2279a pin 1, circuit 720 (RD/YE), harness side and ground; and measure the voltage between the navigation system module C2279a pin 2, circuit 194 (PK), harness side and ground.
  
  Fig 1: Measuring Voltage Between Navigation System Module C2279A Pin 1 Circuit 720 (RD/YE)
  Courtesy of FORD MOTOR CO.
- Are the voltages greater than 10.5 volts?
- Yes : GO to A2.
- No : REPAIR the circuit in question. CLEAR the DTCs. REPEAT the self-test.
A2 CHECK CIRCUIT 694 (BK/LG) FOR AN OPEN
- Key in OFF position.
- Measure the resistance between the navigation system module C2279a pin 13, circuit 694 (BK/LG), harness side and ground.
  
  Fig 2: Measuring Resistance Between Navigation System Module C2279A Pin 13 Circuit 694 (BK/LG)
  Courtesy of FORD MOTOR CO.
- Is the resistance less than 5 ohms?
- Yes : REFER to MODULE COMMUNICATIONS NETWORK to continue communication diagnostics.
- No : REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test.