1. Connect the voltmeter or a lamp sampler on 12 V between a wire of giving of food on glow plugs and the weight (metal of the power unit or a body of the car). Track that there was no short circuit of an electrical wiring of food on weight.
2. Ask the assistant to include ignition and make sure of serviceability of giving of food on candles. Record duration of the period of operation of a control lamp of system and time during which candles remain energized. Switch off ignition.
3. At air temperature in a motive compartment of 20 °C the control lamp has to remain included within 5 ÷ 6 seconds. On the expiration of the stipulated time food continues to move on candles within about 10 more seconds. With fall of temperature duration of burning of a lamp increases and vice versa.
4. If food does not move, it is necessary to check a condition of the relay of system of preheat and a connecting electrical wiring.
5. For identification of a defective glow plug perform the following operations: on the models equipped with a turbocompressor remove the built-in cooler (Intercooler), on models without turbo-supercharging with the D9B engine remove an air distributor casing. In case of need remove an inlet air duct and disconnect a ventilating hose from a jellied mouth of motive oil. For more details see the Power supply system - diesel models. Give fixing nuts, remove washers (if they are provided), then disconnect the main giving wire(s) and the tire of power supply from candles. Try not to drop nuts and washers.
5. By means of the ohmmeter connected to the positive plug of the battery or a lamp sampler check existence of conductivity between the plug of each of candles of an incandescence and weight for 12 V. Resistance of a serviceable candle has to be very little (less than 1 Ohm) therefore if the lamp sampler does not work, or the ohmmeter fixes higher resistance, the corresponding candle is subject to replacement.
7. In the presence of a possibility of use of the ampermeter it is possible to make check of current, the incandescence proceeding through each of candles. After initial jump in 15 ÷ 20 A, value has to be stabilized around 12 A. Otherwise the corresponding candle is faulty and is subject to replacement.
8. In conclusion remove candles and make visual check of their state (see further).