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.
1995 Geo Prizm Base, StandardFACTORY OEM SERVICE PROCEDURE
Power Circuit Checks
- Using a voltmeter, check for battery voltage between ECM constant battery power terminals and ground. See WIRING DIAGRAMS to determine ECM power terminals. If battery voltage is not present, check ECM power supply fuse. If fuse is okay, check for open in power supply or ECM wiring.
- Turn ignition switch to ON position. Using a voltmeter, check for battery voltage between ECM ignition power terminals and ground. If battery voltage is not present, check power supply fuse(s). If fuse is okay, check for an open in wiring between fuse and ECM, or check for a defective ignition switch.
- Connect voltmeter between ground and ECM start (crank) signal terminal. Turn ignition switch to the START position. Battery voltage should be present between ECM start terminal and ground ONLY when ignition switch is in START position. If voltage is not present, check fuse(s). If fuse is okay, check for an open in wiring between fuse and ECM, or check for a defective ignition switch.
Factory Service Tools
Use the Manual With the Right Hardware
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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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