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.
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HOMESERVICE MANUALSTOYOTA1990TERCEL BASE, 2D COUPE, STANDARDREPAIR AND DIAGNOSIS (SINGLE PAGE)ENGINE PERFORMANCESYSTEMENGINE CONTROLS - SYSTEM/COMPONENT TESTS - EFIIDLE CONTROL SYSTEMSIDLE-UP SYSTEM
1990 Toyota Tercel Base, 2D Coupe, Standard
Idle-Up System
1990 Toyota Tercel Base, 2D Coupe, StandardSECTION Idle-Up System
- Inspect coolant temperature sensor for correct operation. See ENGINE SENSORS & SWITCHES . For idle-up vacuum switching valve location see Figure. Using ohmmeter, measure resistance between idle-up vacuum switching valve connector terminals. See Fig 1. Resistance should be 30-36 ohms. Ensure no continuity exists between vacuum switching valve case (body) and each terminal. If not as specified, replace vacuum switching valve.
- Ensure air DOES NOT flow between pipe "E" and pipe "F". If okay, apply battery voltage across vacuum switching valve terminals. See Fig 1. Air should now flow between pipe "E" and pipe "F". If air does not flow as indicated, replace vacuum switching valve.
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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.