Ignition coils are designed to generate high voltage electric current to ignite the working mixture in the engine cylinders

Ignition coils (2 pcs.) are mounted on top of the engine. The ignition coil arrangement is shown in Figure 1

Engine ignition coil ZMZ-406 GAZ-2705

Fig. 1. Ignition coil: 1 - magnetic circuit; 2— body; 3 - coil; 4 - secondary winding; 5 - primary winding; 6 - high-voltage output; 7 - compound; 8— fastening bracket

The ignition coil is a transformer.

The primary winding 5 is wound on the magnetic circuit 1, and the secondary winding 3 is wound on top of it in sections.

The windings are enclosed in a plastic case 2. The space between the windings is filled with compound 7.

There are low and high voltage terminals on the case 6.

Low voltage electrical pulses are supplied to the ignition coil from the control unit.

In the ignition coil, they are transformed into high voltage electrical impulses, which are transmitted through wires to the candles.

Electric discharge occurs simultaneously in two candles of the first and fourth cylinders or the second and third cylinders.

For example, one electrical discharge occurs in the candle of the first cylinder when the compression stroke ends there; the second discharge occurs in the candle of the fourth cylinder when the exhaust stroke occurs there.

Electrical discharge in the spark plug of the fourth cylinder during the exhaust stroke does not affect the operation of the engine.

With further rotation of the crankshaft, an electrical discharge will occur in the fourth candle, causing high voltage leakage and insulation breakdown.

If oil gets on the wires, they should be wiped with a rag soaked in gasoline.

If necessary, check the condition of the current-carrying core of the wire with an ohmmeter.

The resistance of the wires to the 1st and 2nd cylinders should be no more than 1000 Ohms, and the wires to the 3rd and 4th cylinders - no more than 900 Ohms.

Removing the ignition coil

Disconnect the wire from the "negative" terminal of the battery.

Engine ignition coil ZMZ-406 GAZ-2705

Disconnect from coil 4 blocks 1 of low-voltage wires and high-voltage wires 5. Unscrew bolts 2, remove bar 3 and coil 4.

Remove the second coil in the same way.

Checking the ignition coil

Coils 30.3705 and 301.3705 are checked by a spark plug diagnostician 1AP975000 on a car. To do this, disconnect the high-voltage wires from the coil and connect the diagnostician instead.

Then crank the engine with a starter, while a spark should jump in the diagnostic spark gap in time with the operation of the cylinders.

Check the primary resistance of the ignition coil by connecting an ohmmeter between the low voltage terminals. The ohmmeter should show a resistance of 0.4 - 0.5 ohms.

Then check the resistance of the secondary winding by connecting an ohmmeter between the high voltage terminals of the ignition coil. The ohmmeter should show a resistance of 5 - 7 kOhm.

If the measured parameters differ from those indicated, the coil must be replaced.