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.
Ignition System - BOSCH Hall Effect: Operation
The Hall Effect sending unit is mounted inside the distributor on a switch plate. A trigger wheel attached to the distributor shaft under the rotor, passes in and out of the air gap of the Hall Effect sending unit. There is 1 trigger wheel shutter for each cylinder of the engine. Shutter width determines dwell, which is not adjustable.
At speeds greater than 940 RPM, the Hall Effect sending unit signals the ignition control unit to make and break current flow in the primary circuit of the ignition coil.
As the ignition control unit breaks the primary circuit through the coil, secondary voltage is released through the high tension wiring, distributor cap and rotor to the spark plugs.
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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.