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Home >> Chevrolet >> 1997 >> C3500 HD 7.4 J, Automatic >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 3 (Engine Controls - Tests W/Codes - 6.5L) >> Diagnostic Trouble Codes >> DTC P0568 - Cruise Set Circuit >> Diagnostic Procedures

Diagnostic Procedures

WARNING: This page is about a different variant/trim than selected.
  1. Perform Powertrain ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK. See the BASIC TESTING - 6.5L DIESEL article. Then go to next step.
  2. Install scan tool. Turn ignition on, with engine off. Turn cruise switch off. If scan tool displays set switch is on, go to next step. If scan tool does not display that set switch is on, go to step 4).
  3. Turn ignition off. Disconnect PCM harness connector. Turn ignition on. Using a test light connected to ground, probe set switch signal circuit of PCM connector. If test light illuminates, go to step 5). If test light does not illuminate, go to step 6).
  4. DTC is intermittent. If no additional DTCs are set, see DIAGNOSTIC AIDS. If any additional DTCs are set, go to applicable DTC test.
  5. Check for short to voltage in set switch signal circuit or set switch stuck in ON position. Repair as necessary. After repairs, go to step 8).
  6. Replace PCM. After replacing PCM, go to next step.
  7. Using scan tool, select DTC, CLEAR INFO. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter DTC P0568. Operate vehicle within the conditions for setting this DTC. If scan tool indicates that this test ran and passed, go to next step. If scan tool does not indicate that this test ran and passed, repeat step 2).
  8. Using scan tool, select CAPTURE INFO, REVIEW INFO. If any undiagnosed DTC(s) are displayed, go to applicable DTC test.
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