Inspection Procedure 2

INSPECTION PROCEDURE 2: Scan Tool Communication with ECM or PCM Is Not Possible.

Data Link Connector Circuit Part 1:

Data Link Connector Circuit Part 2:

CIRCUIT OPERATION
- A diagnostic output is made from the ECM or the PCM (terminal No. 15) to the diagnostic output terminal (terminal No. 7) of the data link connector.

COMMENT
- No power supply to ECM or PCM .
- Defective ground circuit of ECM or PCM .
- Defective ECM or PCM .
- Improper communication line between ECM or PCM and scan tool.

TROUBLESHOOTING HINTS (The most likely causes for this case)
- Malfunction of ECM or PCM power supply circuit.
- Malfunction of the ECM or the PCM .
- Open circuit between ECM or PCM and data link connector.

DIAGNOSIS

STEP 1. Check harness connector B-18 at ECM or PCM for damage.

Q: Is the harness connector in good condition?

YES: Go to Step 2.

NO: Repair or replace it. Then confirm that the malfunction symptom is eliminated.

STEP 2. Check for open circuit, short circuit to ground and harness damage between data link connector C-125 (terminal No. 7) and ECM or PCM connector B-18 (terminal No. 15).

NOTE: Check harness after checking intermediate connectors C-21. If intermediate connector C-21 is damaged, repair or replace it. Then check that the malfunction is eliminated.

Q: Is the harness wire in good condition?

YES: Refer to INSPECTION PROCEDURE 28 - Power Supply System and Ignition Switch-IG System. Inspection Procedure 28

NO: Repair it. Then confirm that the malfunction symptom is eliminated.