NOTE: Federal Vanagon models use a Bosch single breaker distributor. The Audi Quattro uses the Bosch-Hitachi Digital Timing Control system. See appropriate article in the Computerized Engine Control section.

The Bosch Hall Effect electronic ignition system consists of a breakerless Hall Effect distributor, a Hall (ignition) control unit, ignition coil, ignition switch, and battery.

Closely allied with the ignition system on Audi, Porsche and Volkswagen models is an idle stabilizer, a solid state control unit located between the Hall (ignition) control unit and the distributor's Hall generator.

It replaces the distributor in sending signals to the ignition control unit when engine speeds fall below 940 RPM.

NOTE: Saab models do not use an idle stabilizer. On Audi 4000 (with 5-cylinder engines) and 5000 models, a gray-colored impedance transformer is installed in place of the idle stabilizer. Its purpose is to prevent interference and protect instruments from excessive voltage.

The Hall Effect distributor has normal centrifugal and vacuum advance mechanisms. See Figure and Figure.

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.

Safety Warning

BOSCH Hall Effect Electronic Ignition: Description

Use the Manual With the Right Hardware

When to See a Mechanic

Rather have a pro handle this?