It is possible, however, that one or even several damaged glow plugs will go unnoticed during warm weather. However, after the first cool nights, everything will open: the engine starts with great difficulty or does not start at all.
System troubleshooting
1. First check if there is voltage in the red positive wire of the preheater control.
2. If there is voltage, then check whether electric current is supplied to the glow plugs.
3. If the power to the candles is supplied properly, then it is necessary to check whether the glow plugs are working.
Checking for electricity
1. Connect a test lamp between the ground and the connector of the wire that supplies current to the glow plugs.
2. Turn the ignition key to position «heating». The test lamp should light up. This means that the supply of glow plugs with electric current is in order.
3. If the test lamp does not come on, the preheater control, ignition switch, or lead wire is defective.
Checking glow plugs
A faulty glow plug can be identified as follows:
1. Disconnect wires from cylinders 1 and 2.
2. Disconnect the wires from the glow plugs.
3. Connect the test lamp wire to the positive pole of the battery.
4. With the test tip of the lamp, in turn, touch each thread of the glow plugs. Where the lamp fails to light, there is a broken candle.
5. In this way, you can only determine a completely faulty glow plug, but at the same time you will not be able to determine a candle that heats up weakly or does not heat up at all. Therefore, checking glow plugs by external inspection remains the most reliable type of control:
6. Remove the nozzles as described in the section Diesel injection system.
7. Leave the glow plug wire connected.
8. Turn the ignition key to the preheat position.
9. Through the hole in the cylinder head, see which of the candles glowed weakly or did not glow at all.
10. Replace faulty glow plugs, or if you want to be on the safe side, replace the entire set of glow plugs.
Checking the preheater control device
If it is suspected that the preheater control is the cause of the engine not starting, then you should first check that its connectors are connected correctly and that there is no oxide on them. Often they are the cause of a malfunction due to a loss of voltage. The figure shows:
1 - plug connection for switched positive, full load microswitch, thermal switch, starter (+), preheating indicator lamp, cold start movement solenoid valve and ground;
2 - power supply for glow plugs No. 1 and 2, as well as 3 and 4; direct battery connection (+).
1. Disconnect the wire from the glow plugs.
2. Connect a test lamp between the end of the unscrewed wire and ground.
3. Turn the ignition key to the preheat position and watch the test lamp: it should be on until the preheat control lamp goes out.
4. Briefly turn on the starter. When the starter is cranking, the test lamp should be on, otherwise the wire to the preheater control may be broken.
5. If the test lamp does not light, then the control device is faulty. It is also possible that one of the lead wires, the shut-off valve, or the entire ignition lock is also faulty.