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.
1991 Geo Prizm LSi, StandardFACTORY OEM SERVICE PROCEDURE
Circuit Opening Relay
- Circuit opening relay is located behind center console of instrument panel. Relay is mounted on bracket attached to the ECM. Relay contains a 6-pin Black connector.
- Disconnect electrical connector from circuit opening relay. Using ohmmeter, ensure continuity exists between Black and White/Black wire terminals and Black/Red and Green/Red wire terminals.
- Ensure no continuity exists between Black/Red and Blue/Black wire terminals. Replace circuit opening relay if continuity is not as specified.
- Apply battery voltage to Black wire terminal and ground White/Black wire terminal. Ensure continuity exists between Black/Red and Blue/Black wire terminals. Disconnect battery voltage.
- Apply battery voltage to Black/Red wire terminal and ground Green/Red wire terminal. Ensure continuity exists between Black/Red and Blue/Black wire terminals. Disconnect battery voltage. Replace circuit opening relay if defective.
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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