Reading and Clearing Diagnostic Trouble Codes

Data Link Connector Location:

When trying to verify a speed control system electronic malfunction: Connect a DRB scan tool if available to the data link connector. The connector is located at left side of the steering column, and at lower edge of the panel.

1. A speed control malfunction may occur without either diagnostic code being indicated. If no diagnostic code appears conduct test in the following paragraphs depending on failure mode. If a code is observed, refer to the appropriate Powertrain Diagnostic for the electrical circuit diagnostic.

Speed Control Slows Down By Itself
Test vehicle speed sensor. If sensor fails replace sensor, if it passes perform the following test:
1. Perform the speed control switch test on the SET/COAST switch, if it fails replace switch.
2. If the switch passes, conduct the vacuum supply test.
3. If it passes, conduct the servo vacuum test. If it fails replace servo.
4. If servo passes, replace the PCM.

NOTE: The pinion factor must be set for all new transmission control modules. If the pinion factor is not set or if it is set incorrectly, any speed-related accessories will not operate or will operate inaccurately. This includes the speedometer, speed control, rolling door locks, and other devices that are operated by the powertrain and body control modules. For instructions on setting the pinion factor, see the appropriate transmission diagnostic procedures or the service procedures.