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.
1989 Geo Prizm Base, AutomaticFACTORY OEM SERVICE PROCEDURE
Throttle Position Sensor/Idle Switch (Metro A/T)
- With battery disconnected, insert feeler gauge with a thickness of .012" (.3 mm) between throttle stop screw and throttle lever. Using an ohmmeter, check between terminals "A" and "B" (idle switch) to ensure there is continuity.
- Remove feeler gauge and replace with feeler gauge of .035" (.9 mm) thickness. Check between terminals "A" and "B" (idle switch) to ensure there is no continuity.
- Ensure there is 4370-8130 ohms of resistance between terminals "A" and "D". With throttle valve in idle position, ensure there is 240-1140 ohms of resistance between terminals "A" and "C". With throttle valve in fully open position, ensure there is 3170-6600 ohms of resistance between terminals "A" and "C".
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.