Data Link Connector: Testing and Inspection

Diagnostic Circuit:

VOLTAGE CHECKS
1. With ignition "ON", connect test lead to socket 2 on diagnostic unit.
2. Check voltage across ECU terminals 55 (+) and 19 (-).
3. Voltmeter should indicate 12 VDC.
4. Press test button and check voltage.
5. Voltmeter should now indicate ) VDC.
6. If no voltage is present, check diagnostic connector.
7. If voltmeter indicates 12 VDC with test button depressed, check diagnostic unit.

Socket Test:

DIAGNOSTIC CONNECTOR
1. With ignition "ON", check voltage between Blue diagnostic connector lead and ground.
2. Voltmeter should indicate 12 VDC.

Socket Test:

3. With ignition "OFF", check resistance between Black diagnostic connector lead and ground
4. Ohmmeter should indicate 0 Ohms.

Socket Test:

DIAGNOSTIC UNIT
1. With ignition "OFF", check resistance between diagnostic terminal directly under test button and diagnostic test lead.
2. Ohmmeter should indicate infinite resistance.
3. Press test button and observe Ohmmeter.
4. Ohmmeter should now indicate 0 Ohms.

Socket Test:

5. Connect diode tester between diagnostic unit test lead (-) and terminal directly below LED (+).
6. If diode tester indicates bad diode, replace diagnostic unit.