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 Geo Prizm Base, 4D Hatchback, AutomaticFACTORY OEM SERVICE PROCEDURE
Cold Start Switch
- With engine temperature at less than 95°F (35°C), disconnect cold start switch Brown connector, located below distributor. Using an ohmmeter, ensure resistance across cold start switch terminals is 20-60 ohms.
- Ensure resistance between Black/White wire on cold start switch and ground is 20 ohms or less. Replace cold start switch if resistance is not as specified.
Factory Service Tools
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
Disclosure: Verified tool recommendations may earn an affiliate commission at no cost to you.
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.