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.
1979 Honda Prelude Automatic TransFACTORY OEM SERVICE PROCEDURE
1976 Models
- Perform DASHPOT SYSTEM test. By-pass the speed sensor by applying battery voltage to Yellow/Black wire at emission control box connector.
- Squeeze vacuum hose shut between dashpot solenoid valve and carburetor. Raise engine speed to 3500 RPM and release throttle. Engine should return to idle in 2-8 seconds. If return time is out of limits, remove throttle control valve cover.
- Loosen lock nut on valve and turn adjusting nut clockwise to decrease return time or counterclockwise to increase return time. Tighten lock nut and retest. If return time cannot be increased, measure voltage at throttle positioner solenoid.
- If voltage (12 volts) exists, replace either throttle positioner solenoid or throttle control valve. To test throttle control valve, remove vacuum hose and check for vacuum. If vacuum exists, throttle control valve is 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.