Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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HOMESERVICE MANUALSCHEVROLET1985CHEVY VAN G20, 6.2 C, STANDARDREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 17 (ENGINE CONTROLS - TESTS W/CODES - 5.7L)SELF-DIAGNOSTIC SYSTEMDIAGNOSTIC PROCEDURE
1985 Chevrolet Chevy Van G20, 6.2 C, Standard
Diagnostic Procedure
1985 Chevrolet Chevy Van G20, 6.2 C, StandardSECTION Diagnostic Procedure
WARNING: This page does not describe the selected car, but rather 20 other vehicles, including the 1994 GMC Yukon, 1994 GMC Vandura Special, 1994 GMC Vandura, 1994 GMC Suburban, and 1994 GMC Rally Camper Special. However, it is still accessible from the selected car via links, so may be relevant.
Diagnosis of the computerized engine control system should be performed in the following order:
- Ensure all engine systems not related to the computer are operating properly. DO NOT
proceed with testing unless all other problems have been repaired. Perform diagnostic circuit check before using trouble code charts. See appropriate BASIC TESTING
article in this section. See below.
- BASIC TESTING - GASOLINE (for "C" & "K" Series)
- BASIC TESTING - GASOLINE (For "G" & "P" Series)
- If trouble codes were displayed (other than Code 12), determine whether codes are hard or intermittent. Hard codes cause Malfunction Indicator Light (MIL) to illuminate continuously with engine running. See HARD OR INTERMITTENT TROUBLE CODE DETERMINATION . For diagnosing hard codes, proceed to appropriate trouble code chart. For diagnosing intermittent codes, proceed to INTERMITTENTS in appropriate TESTS W/O CODES
article in this section. See below. Exceptions are Code 13, 15, 24, 44 and 45 charts, which can help diagnose intermittent codes.
- TESTS W/O CODES - GASOLINE (for "C" & "K" Series)
- TESTS W/O CODES - GASOLINE (For "G" & "P" Series)
- If trouble codes were not displayed and a driveability problem exists, refer to SYMPTOMS in appropriate TESTS W/O CODES
article in this section above. From there you will be sent to the appropriate area in appropriate I - SYS/COMP TESTS article in this section. See below.
- SYSTEM/COMPONENT TESTS - GASOLINE (for "C" & "K" Series)
- SYSTEM/COMPONENT TESTS - GASOLINE (For "G" & "P" Series)
- After repairs are made, clear trouble codes and perform FIELD SERVICE MODE CHECK in appropriate BASIC TESTING
article in this section. See below.
- BASIC TESTING - GASOLINE (for "C" & "K" Series)
- BASIC TESTING - GASOLINE (For "G" & "P" Series)
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.