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.
1986 Honda Prelude Base, AutomaticFACTORY OEM SERVICE PROCEDURE
Hot Engine
- Ensure engine is at normal operating temperature. On Prelude models, disconnect hose No. 14 from control box No. 1 and install a plug in control box No. 1. See Fig 1 and Figure .
- On all models, start engine and check that frequency solenoid valves A and B are operating while running engine at 2500 RPM.
- Frequency valves should emit a clicking sound. It may be easier to place hand on each individual valve to feel movement. If either solenoid A or B is inoperable, replace valve and retest. If both solenoid valves operate properly, proceed to step 6).
- If either solenoid A or B are inoperable, check for voltage at terminal lead wires while engine is running at 2500 RPM. If voltmeter fluctuates between 12 volts and zero volts, replace solenoid valves and retest.
- If voltmeter indicates 12 volts and engine operating condition is normal, check vacuum lines of system for blockage, leaks or disconnected hoses. If there still is no problem, check each air control valve A and B.
- If voltmeter indicates zero volts, proceed to TROUBLE SHOOTING . If voltmeter indicates 12 volts and engine operating condition is abnormal, or the engine stops, proceed to TROUBLE SHOOTING .
- Reconnect vacuum hoses. Then, with A/C, radiator fan, heater blower motor, rear window defogger and headlights off, ensure that frequency solenoid valves are inoperable while engine is at idle speed.
- If solenoid valves are inoperable, the system is okay and testing is complete. If solenoid valves do operate, proceed to TROUBLE SHOOTING .
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.