Accessing and Reading Diagnostic Trouble Codes

There are two methods for reading trouble codes:

Monitor Connector:

Method 1: DLC Procedure

Using the four cavity Data Link Connector (DLC), located behind the passenger kick panel, ground terminal 3 to terminal 2. Refer to the accompanying image for DLC terminal locations.

Diagnosis Switch Terminal:

Method 2: Diagnosis Switch Terminal Procedure

Installing a fuse in the Diagnosis Switch Terminal, located in the main fuse block, activates the diagnostic mode.

The Electronic Control Module (ECM) will then toggle the "CHECK ENGINE" light to emit any trouble codes stored in the ECM. The output of Code 12 indicates that the "CHECK ENGINE" light is operating normally and will flash if no codes exist. If trouble code(s) exist the lowest numbered code will flash first after Code 12 has been flashed. Each code will flash 3 times. If no codes exist and a driveability problem is present, see DIAGNOSIS BY SYMPTOM. If codes are stored, see DIAGNOSTIC CHARTS.

To clear the codes from the memory of the ECM, either to determine if the malfunction will occur again or because repair has been completed, the ECM power feed must be disconnected for at least thirty (30) seconds. To remove power from the ECM, remove the 30A main fuse, from relay/fuse center under hood. The negative battery terminal may be disconnected, but this will erase memory in the clock and/or radio.

CAUTION: To prevent ECM damage, the key must be "OFF" when disconnecting or reconnecting ECM power.