Do not ground the ignition coil, otherwise the coil and / or pulse sensor may fail.
On models equipped with Motronic, a faulty ECU can cause damage to the ignition coil. Do not forget, if the engine does not start and there is a suspicion of an ECU malfunction, check the ignition coil.
1. Mark the wires and terminals, and then disconnect the high voltage wire and primary circuit wires from the ignition coil.
2. Remove the ignition coil mountings, then clean the outside of the coil and inspect for cracks or other damage.
3. Inspect the primary circuit terminals and ignition coil high voltage contact for corrosion. Remove any corrosion with a wire brush.
4. Check the resistance of the primary winding of the ignition coil by connecting an ohmmeter to its terminals. Some Motronic systems use a different type of coil. First, remove the coil cover and use an ohmmeter to measure the resistance between the primary terminals of the ignition coil.
5. Compare the measured resistance with the requirements Tables of sizes and adjustment data at the end of the Guide.
6. Check the resistance of the secondary winding of the ignition coil by connecting one probe of an ohmmeter to one of the terminals of the primary winding, and the second probe to the high voltage contact of the ignition coil.
7. On TCI systems, connect an ohmmeter between terminal 1 (-) ignition coils and central contact. On Motronic systems, connect an ohmmeter between terminal 15 () ignition coils and central contact. Compare measured resistance with requirements Tables of sizes and adjustment data at the end of the Guide.
8. If the measured resistances differ noticeably from those indicated, the coil is defective and must be replaced. Please note that the resistance depends on the temperature of the coil, so do not rush to reject the coil if the resistance differs slightly.
9. Dry and clean condition of the wires is essential for the correct operation of the ignition system.
10. Install the coil on its holder and connect the wires. Installation is reverse to removal.