Pinpoint Test A: No Communication With The Vehicle Security Module

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

A1 CHECK THE VOLTAGE TO THE VEHICLE SECURITY MODULE
- Key in OFF position.
- Disconnect: Vehicle Security Module C3203e.
- Key in ON position.
- Measure the voltage between the vehicle security module C3203e-3, circuit 645 (WH/LB), harness side and ground; and between the vehicle security module C3203e-1, circuit 456 (DG/OG), harness side and ground.
  
  Fig 1: Checking Voltage To Vehicle Security Module
  Courtesy of FORD MOTOR CO.
- Are the voltages greater than 10 volts?
- Yes : GO to A2.
- No : REPAIR the circuit in question. CLEAR the DTCs. REPEAT the self-test.
A2 CHECK CIRCUIT 1205 (BK) FOR AN OPEN
- Key in OFF position.
- Disconnect: Vehicle Security Module C3203d.
- Measure the resistance between the vehicle security module C3203d-14, circuit 1205 (BK), harness side and ground.
  
  Fig 2: Measuring Resistance Between Vehicle Security Module C3203d-14, Circuit 1205 Harness Side And Ground
  Courtesy of FORD MOTOR CO.
- Is the resistance less than 5 ohms?
- Yes : REFER to MODULE COMMUNICATIONS NETWORK to continue communication diagnosis.
- No : REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test.