Reading and Clearing Diagnostic Trouble Codes

When trying to verify a speed control system electronic malfunction, one of two methods may be used and are described as follows:

USING DIAGNOSTIC TOOL
If a Diagnostic Readout Box (DRB) is available, plug tool into diagnostic connector and verify that either a diagnostic trouble code 15 or 34 is indicated, then refer to the appropriate diagnostic chart. Follow tool manufacturers instructions for proper installation of the tool prior to testing speed control system.

If no problems were found, replace engine controller.

USING VOLTMETER
If a DRB Diagnostic tool is not available, check for diagnostic trouble codes as follows:

1. Cycle ignition switch to On position three times. On third cycle, leave switch in On position.
2. Observe Check Engine indicator on instrument cluster. If a diagnostic trouble code is present, indicator lamp will flash (blink) in a series which will show which diagnostic trouble code is the problem.
3. If diagnostic trouble code 34 is observed, determine source of problem by performing component tests.
4. If diagnostic trouble code 15 is present, testing of the distance sensor is required. Testing of the distance sensor requires the use of the DRB diagnostic tool.
5. If no problems were found, replace engine controller.