Pinpoint Test G: The Powertrain Control Module (PCM) Does Not Respond To The Diagnostic Tool

WARNING: This page is about a different car, the 2004 Mercury Mountaineer and 2004 Ford Explorer. However, it is still accessible from the selected car via links, so may be relevant.

G1 CHECK THE PCM C175b
- Key in OFF position.
- Disconnect: PCM C175b
- Inspect the PCM C175b for damage.
- Is the PCM C175b OK?
Yes

GO to G2.

No

REPAIR the PCM C175b. CARRY OUT the data link diagnostics test.
G2 CHECK CIRCUITS 3125 (RD/YE) AND 3126 (TN/YE) BETWEEN THE PCM C175b AND THE DLC C251 FOR AN OPEN
- Measure the resistance between PCM C175b-23, circuit 3125 (RD/YE), harness side and the DLC C251-14, circuit 3125 (RD/YE), harness side.
  
  Fig 1: Check Circuits 3125 (RD/YE) And 3126 (TN/YE) Between PCM C175B And DLC C251 For An Open (1 Of 2)
  Courtesy of FORD MOTOR CO.
  
  Fig 2: Check Circuits 3125 (RD/YE) And 3126 (TN/YE) Between PCM C175B And DLC C251 For An Open (2 Of 2)
  Courtesy of FORD MOTOR CO.
- Are the resistances less than 5 ohms?
Yes

GO to G3.

No

REPAIR the circuit in question. CLEAR the DTCs. REPEAT the self-test. CARRY OUT the data link diagnostics test.
G3 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 POWERTRAIN CONTROL MODULE (PCM) for 4.0L or POWERTRAIN CONTROL MODULE (PCM) for 4.6L CLEAR the DTCs. REPEAT the self-test. CARRY OUT the data link diagnostics test.

No

The system is operating correctly at this time. Concern may have been caused by a loose or corroded connector. CLEAR the DTCs. REPEAT the self-test. CARRY OUT the data link diagnostics test.