How to Troubleshoot the Ignition System in a VW Beetleby Contributor; Updated November 07, 2017
Items you will need
Spark plug gapping tool
Replacement ignition coil
How to Troubleshoot the Ignition System in a VW Beetle. The next generation of the Beetle came with the next generation of ignition systems. Much of the system is controlled by its Powertrain Control Module. Objects like the fuses and spark plugs are still okay for you to check, but everything else should be looked over by a specialist.
Switch off everything that uses electricity on the Beetle. This includes the lights, air conditioner and rear window defroster.
Engage the parking brake to keep the daylight driving lights off. Place the selector lever (gear shift) into "Park."
Make sure the fuses for the ignition coils are okay. The fuse box should be behind an access panel on the side of the dashboard near the driver's door.
Check the battery's voltage with a digital multimeter. It needs to be at least 11.5 volts.
Look over the ground connections between the engine and chassis. Make sure they are clean and free of any corrosion.
Inspect the spark plugs. Check them for wear or deposits and clean them with a stiff brush. Use a round-wire type gapping tool to ensure the gap between the electrodes is correct.
Replace the ignition coil. Disconnect the negative battery cable and four-pin connector from the coil, then remove mounting bolts and the coil vertically from the spark plug. Push the new coil by hand onto the spark plug and connect everything in reverse order.
You can monitor the ignition timing on a scan tool by connecting it to the DLC in the vehicle. However, Volkswagen does not give out the timing specification, and you can't adjust it. You can adjust a new spark plug's side electrode if the gap is wrong. The gapping tool should have a bending tool attached. However, don't adjust the gap on a used platinum spark plug. Replace the ignition coil sealing ring when changing a coil if it is damaged.
The power output stage is part of the Beetle's ignition coil and cannot be separated.