Reading and Clearing Diagnostic Trouble Codes

When trying to verify a speed control system electronic malfunction, one of two methods may be used; the Diagnostic Readout Box (DRB) or by reading the Malfunction Indicator Lamp (MIL) on the instrument cluster.

USING DIAGNOSTIC TOOL
If a DRB Diagnostic Tool is available, plug tool into six way diagnostic connector located at righthand side of steering column, at lower edge of knee bolster, and verify that either a diagnostic trouble code 15 or 34 is indicated, then refer to the appropriate Diagnostic Chart.

READING MALFUNCTION INDICATOR
1. With key inserted in ignition switch, cycle switch to ON position three times. On third cycle, leave switch in ON position.
2. Observe the MIL on the instrument cluster. If a diagnostic trouble code is present, the lamp will flash in a series which will indicate the problem. For example, a series of three flashes in rapid succession, a slight pause, then four flashes in rapid succession would indicate diagnostic trouble code 34.
3. If no diagnostic trouble code appears or diagnostic trouble code 15 or 34 is observed, refer to Diagnostic Charts.