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.
1990 Chevrolet Corvette Base, 2D Convertible, StandardFACTORY OEM SERVICE PROCEDURE
Trouble Code Definition
ECM/PCM TROUBLE CODE DEFINITION
| Code No. | Circuit Affected | ||
|---|---|---|---|
| 12 (1) | No RPM Reference Pulse | ||
| 13 | Open Oxygen Sensor Circuit | ||
| 14 | CTS Signal Voltage Low | ||
| 15 | CTS Signal Voltage High | ||
| 21 | TPS Signal Voltage High | ||
| 22 | TPS Signal Voltage Low | ||
| 23 | MAT Sensor Signal Voltage High | ||
| 24 | Vehicle Speed Sensor Circuit | ||
| 25 | (IAT) MAT Sensor Signal Voltage Low | ||
| 33 | MAP Sensor Signal Voltage High | ||
| 34 | MAP Sensor Signal Voltage Low | ||
| 41 | Cylinder select Error | ||
| 42 | EST Circuit Open Or Grounded | ||
| 43 | ESC Error | ||
| 44 | Lean Exhaust Indication | ||
| 45 | Rich Exhaust Indication | ||
| 46 | Anti-Theft System Fault | ||
| 51 | Faulty PROM, MEM-CAL or ECM/PCM | ||
| 52 | Low Engine Oil Temperature | ||
| 53 | System Overvoltage | ||
| 54 | Fuel Pump Voltage Low | ||
| 62 | High Engine Oil Temperature | ||
|
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NOTE:
Trouble code charts should only be used if SERVICE ENGINE SOON light is illuminated (indicating a current problem exists). Exceptions are Code 13, 15, 24, 44 and 45 charts, which may be used to help diagnose intermittent codes. Anytime control module-related Codes 51, 52 or 55 are displayed with another code, start with 50-series code first, then proceed to low profile numbered codes.
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.