Volkswagen Front Wheel Drive 1974-1989 Repair Guide

Ignition System Precautions


See Figure 1

Make sure the ignition switch is OFF before connecting or disconnecting any wiring or test equipment.
When cranking the engine without starting, as for a compression test, disconnect the high tension coil wire from distributor and ground it to the engine block or head.
DO NOT install a standard ignition coil in the system.
DO NOT connect a condenser/suppressor or powered test light to the negative terminal (1) of the ignition coil.
DO NOT connect any 12-volt test instruments to the positive terminal (15) of the ignition coil. The electronic control unit will be permanently damaged.
When jump starting with a booster, DO NOT connect a quick-charger for more than 1 minute, nor exceed 16.5 volts with the booster.
An adaptor must be used when connecting a conventional tachometer to carbureted engines with electronic ignitions. Use the illustration as a guide to construct your own. The components should be available at your local electronics store. Connect the positive wire of the tachometer to the adapter and the negative wire to ground.
Always switch the multimeter to the appropriate measuring range BEFORE making the test connections. Use a high-impedance digital multimeter which is designed for testing computerized electrical components.
Do not use a standard test light (electric bulb type) on electronic circuits. The high electrical consumption of these test lights can lead to electronic component damage.
Unless otherwise noted, always disconnect the main fuel injection harness on Digifant II engines if you must crank the engine during ignition system testing.

Click image to see an enlarged view

Fig. Fig. 1: Tachometer adaptor for carbureted engines with electronic ignitions