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.
Engine Speed Sensor
The engine speed signal comes from the Hall Effect Unit mounted above the distributor on the 2.5L engine and from terminal "R" of the conventional HEI module in the distributor on all other models. Pulses from the distributor are sent to the ECM where the time between these pulses is used to calculate engine speed. The ECM adds spark advance modifications to the signal and sends the signal back to the distributor.
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Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
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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.