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 Cavalier Base, 4D Wagon, 3.1 T, Automatic, 125C/MD9FACTORY OEM SERVICE PROCEDURE
Output Signals
NOTE:
Each vehicle may be equipped with different combinations of computer controlled components. The following listed components may NOT be used on all models. For theory and operation on each output component, refer to the system indicated in brackets, to the right of each component.
- Air Injection Control Solenoid (Emission Systems)
- Canister Purge Valve (Emission Systems)
- SERVICE ENGINE SOON Light (Self-Diagnostic System)
- Computer Controlled Coil Ignition - C(3)I (Ignition System)
- Direct Ignition System - DIS (Ignition System)
- EGR Control Solenoid Valve (Emission Systems)
- ESC Timing Retard (Ignition System)
- Fuel Injectors (Fuel Control)
- Fuel Pump & Fuel Pump Relay (Fuel Delivery)
- HEI-EST Ignition (Ignition System)
- Idle Air Control (IAC) Valve (Fuel Injected - Idle Speed)
- Idle Speed Control (ISC) Motor (Fuel Injected Cadillac - Idle Speed)
- Idle Load Compensator (Carbureted - Idle Speed)
- Integrated Direct Ignition - DIS (Ignition System)
- Mixture Control (M/C) Solenoid - Carbureted 5.0L (VIN Y) (Fuel Control)
- Self-Diagnostics (Self-Diagnostic System)
- Serial Data (Self-Diagnostic System)
- Converter Clutch (Miscellaneous ECM Controls)
- Wastegate Solenoid (Air Induction Systems)
Factory Service Tools
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
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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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