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.
1987 Honda Prelude Si, StandardFACTORY OEM SERVICE PROCEDURE
Speed Sensor
- Raise and support front of vehicle. Connect voltmeter positive probe into Yellow/Black wire terminal at control box No. 1 connector. Connect negative probe to ground. Start engine.
- Select second gear (man. trans.) or position "2" (auto. trans.) and accelerate slowly, while observing voltmeter. Voltage should be battery voltage below 11 MPH and no voltage above 16 MPH. If so, sensor is okay. If not, install a new sensor and retest.
- If there is no voltage during speed sensor test, check for bad electrical connection, fuse or faulty speed sensor. Repair or replace as necessary and retest.
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.
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