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.
BOSCH Electronic Ignition System: Operation
Inside the distributor, a trigger wheel turns with the distributor shaft. The trigger wheel has one tooth or lug for each engine cylinder.
As the trigger wheel rotates past the pole of the magnetic pick-up coil, a magnetic field is created that continually builds and collapses. This produces a low voltage electrical signal.
This signal passes to the control module, which controls the dwell angle and at the same time interrupts the ignition coil's primary circuit. This induces the high secondary coil output voltage that fires 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.