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 MANUALSCHEVROLET1987STEP VAN P20, 6.2 J, STANDARDREPAIR AND DIAGNOSIS (SINGLE PAGE)ENGINE PERFORMANCESYSTEMCCC TBI TESTS W/CODESDIAGNOSTIC CHARTSCODE 55 - ECM PROBLEM
1987 Chevrolet Step Van P20, 6.2 J, Standard
Code 55 - ECM Problem
1987 Chevrolet Step Van P20, 6.2 J, StandardSECTION Code 55 - ECM Problem
Be sure ECM grounds are okay and that MEM-CAL, PROM, and/or CALPAK are properly latched. If okay, replace ECM. Clear codes, confirm "Closed Loop" operation, and no "SERVICE ENGINE SOON" light.
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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.