1. Communication With Scan Tool Impossible (Entire System)

CIRCUIT OPERATION
A battery positive voltage is applied on the data link connector power terminal (terminal 16). The ground terminals (terminal 4, 5) are grounded to the vehicle body.


COMMENT
The cause is probably a defect in power supply system (including ground) for the on-board diagnostic test mode line.

TROUBLESHOOTING HINTS
The most likely causes for this case:
- Malfunction of the data link connector.
- Damaged harness wire.


DIAGNOSIS






STEP 1. Check the power supply line at the data link connector C-23.

Measure voltage between terminal 16 and ground.
- Voltage should be approximately 12 volts (battery positive voltage).

If within specifications, go to Step 2.

If not within specifications, check the intermediate connectors C-66, C-78 and C-85 and repair or replace if needed. If the intermediate connectors C-66, C-78 and C-85 are in good condition, repair the harness wire between the data link connector C-23 and fusible link (6).

Then confirm that the malfunction symptom is eliminated.






STEP 2. Check the ground line at the data link connector C-23.

Check for the continuity between terminal 4, 5 and ground.
- There should be continuity (0 ohms).

If no continuity, repair the harness wire between the data link connector C-23 and the ground.

If continuity, replace the scan tool.

Then confirm that the malfunction symptom is eliminated.