Verification conditions
The voltage of the car's on-board network must be at least 11.5 V.
The engine management system must be in good working order.
Circuit breakers in the voltage supply circuit to the glow plugs must be in good order.
Examination
Switch off the ignition.
Disconnect the electrical connector from the coolant temperature sensor. In this state, the engine management system assumes that the engine is cold and will preheat the engine when the ignition is turned on.
Disconnect the electrical wire connectors from the glow plugs.
Connect a voltmeter with the positive lead to the glow plug wire, the negative lead to «mass». Turn on the ignition and make sure that the voltage to the candles is supplied at the appropriate time.
At an air temperature of 20°C, the time intervals for applying voltage to the glow plugs (control lamp on) should be 5 s. The burn time of the test lamp increases at lower temperatures and decreases when it rises. If voltage is applied to the glow plugs, then the relay and wiring are OK.
Checking glow plugs
Pic. 5.2–1. Diesel Engine Glow Plug
Check each glow plug (pic. 5.2–1) for mechanical damage. Burnt or shattered glow plug tips indicate poor atomization of fuel by the injector. In this case, the injectors must be checked and replaced if necessary.
If there is no mechanical damage on the glow plugs, check their electrical resistance, which should be less than 1 ohm.
The performance of glow plugs can be checked by applying a voltage of 12 V to them. At the same time, they should heat up evenly over the required time interval. In doing so, the following precautions must be observed:
1. Hold the glow plug with a special clamp or pliers.
2. The glow plug circuit must have a fuse.
3. After checking, the glow plug should cool down for a few minutes.
A good glow plug heats up until the bottom of the electrode turns red within 5 seconds. With longer heating or heating not in the lower, but in the middle part, the candle is faulty and must be replaced.
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