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.
1985 Chevrolet Step Van P30, 7.4 W, StandardFACTORY OEM SERVICE PROCEDURE
Trouble Code Identification
ECM TROUBLE CODE IDENTIFICATION
| Code | Circuit Affected | ||
|---|---|---|---|
| 12 | (1) | ||
| 21 | TPS signal voltage high. | ||
| 22 | TPS signal voltage low. | ||
| 24 | VSS circuit. | ||
| 31 | MAP sensor signal voltage low. | ||
| 32 | EGR vacuum circuit. | ||
| 33 | MAP sensor signal voltage high. | ||
| 51 | PROM faulty or improperly installed. | ||
| 52 | Fault in ECM circuit. | ||
| 53 | 5-volt reference circuit overloaded (grounded). | ||
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Factory Service Tools
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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.
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