Pinpoint Test H: THE POWERTRAIN CONTROL MODULE (PCM) DOES NOT RESPOND TO THE DIAGNOSTIC TOOL

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

H1 CHECK THE PCM C175B FOR DAMAGE
- Key in OFF position.
- Disconnect: PCM C175b.
- Inspect the PCM C175b for damage.
- Is the PCM C175b OK?
- Yes : GO to H2.
- No : REPAIR the PCM C175b as necessary. TEST the system for normal operation.
H2 CHECK FOR AN OPEN BETWEEN THE DATA LINK CONNECTOR (DLC) C251 AND THE PCM C175B
- Measure the resistance between the PCM C175b-53, circuit 4-EC7 (GY/RD), harness side and the DLC C251-6, circuit 4-EC7 (GY/RD), harness side.
  
  Fig 1: Measuring The Resistance Between The PCM C175b-53, Circuit 4-EC7 (GY/RD), Harness Side And The DLC C251-6, Circuit 4-EC7 (GY/RD)
  Courtesy of FORD MOTOR CO.
- Measure the resistance between the PCM C175b-54, circuit 5-EC7 (BU/RD), harness side and the DLC C251-14, circuit 5-EC7 (BU/RD), harness side.
  
  Fig 2: Measuring The Resistance Between The PCM C175b-54, Circuit 5-EC7 (BU/RD), Harness Side And The DLC C251-14, Circuit 5-EC7 (BU/RD)
  Courtesy of FORD MOTOR CO.
- Are the resistances less than 5 ohms?
- Yes : GO to H3.
- No : REPAIR the circuit in question. TEST the system for normal operation.
H3 CHECK FOR CORRECT PCM OPERATION
- Disconnect all the PCM connectors.
- Check for:
- corrosion
- push-out pins
- Connect all the PCM connectors and make sure they seat correctly.
- Operate the system and verify the concern is still present.
- Is the concern still present?
- Yes : INSTALL a new PCM. REFER to ELECTRONIC ENGINE CONTROLS . TEST the system for normal operation. CARRY OUT the diagnostic tool data link 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.