Computers and Control Systems: Testing and Inspection

Fig. 2 Coil negative terminal jumper wire:

BE SURE THERE ARE NO FUEL LEAKS BEFORE PERFORMING THIS TEST.

1. Disconnect high tension lead from distributor and hold end of cable 3/16-3/8 inch from good engine ground. Crank engine and check for spark at end of high tension lead.
2. If spark is present, continue cranking engine while slowly moving coil high tension lead away from engine ground. If arcing occurs at coil tower, replace coil. If no spark is present at coil high tension lead or spark is weak, turn ignition On and check voltage at coil negative terminal using suitable voltmeter.
3. If voltage reading obtained is the same as battery voltage, system is operating satisfactorily. If reading is three volts or less, the distributor is defective and must be checked further. If zero reading is obtained, check for open circuit in ignition wiring and repair as necessary.
4. Connect special jumper wire, Fig. 2, to coil negative terminal. Turn ignition On, position coil high tension lead as described in step 1, then momentarily touch other end of jumper wire to a good ground.
5. If no spark is observed at coil high tension lead, check for presence of voltage at coil positive terminal. If battery voltage reading is obtained at coil positive terminal, replace coil. If proper voltage cannot be obtained, check for loose connections or damaged wiring and repair as necessary.