Data Link Connector: Description and Operation

Fig. 2 Trouble Code Test Lead Identification:

The trouble code test lead is located under the dash in the Assembly Line Communications Link (ALCL), Fig. 2.
If the test lead is grounded with engine running, the ECM will control system operation as follows: No trouble codes will be set. The ``Open Loop'' timer will be deactivated and the system will operate in ``Closed Loop'' if oxygen sensor is above 600° F, regardless of coolant temperature. On models with EST, spark advance will be fixed.