Description
1. The swirl chambers of the engine are heated just before the engine is started by electric plugs, commonly referred to as glow plugs. When the ignition key is set to «ON», the warning lamp comes on to inform the driver that the heating process is in progress. When the lamp goes out, the engine is ready to start.
2. The glow plugs are energized through a relay mounted either on the bulkhead of the engine compartment or on/near the upper suspension strut mount (depending on the model). Health check
Note: The following information only applies to 11 volt glow plugs, make sure your vehicle is fitted with the correct type. Checking the health of 5-volt plugs requires special equipment - contact a specialist.
3. If the system is suspected to be faulty, verify that battery voltage is applied to the glow plug rail for a few seconds when the ignition key is set to «ON». If not, the wiring or relay is damaged. You can test the relay by substituting a known-good component.
4. If voltage is applied to the bus, but one or more glow plugs are suspected to be failing, the defective plug can be identified using a long range ammeter (0-50 A). Using an ohmmeter is unlikely to be able to distinguish a good candle (resistance less than 1 ohm) from faulty.
5. Connect an ammeter between the bus bar and the feed wire. Have an assistant turn the ignition key. The current flowing through the grounded plug in the first few seconds of the test is 8 9 A. Thus, if the ammeter reading is much higher or lower than 32-36 A, one or more plugs are faulty. Disconnect each spark plug in turn to identify the faulty one.
6. Alternatively, a 12V bulb can be used. Remove the busbar and connect the bulb between the positive battery terminal and each glow plug in turn. If the lamp is on, or the glow plug is good, or there is a short circuit. If the lamp does not light, the candle is faulty.
7. In addition to the above tests, a visual inspection of a suspected faulty glow plug can be performed. Proceed as follows:
8. Glow plug testers are commercially available, consisting of a housing in which the candle is clamped, an ammeter, 12-volt connecting wires and a simple timer that turns on LEDs at an interval of 5 seconds. Without removing the glow plug, connect it with wires to a 12-volt battery and determine the time required for the tip of the candle to glow, after which the current will drop.
9. Such a device can be made independently.
10. Connect to each terminal of an ammeter with a range of at least 30 A by wire. In the interest of safety, connect one of the wires through a 30A fuse.
11. Remove the presumably faulty glow plug from the cylinder head, clamp it with special pliers in a metal case and attach it to any ground-locked point on the engine. Connect the wire coming from the positive terminal of the ammeter to the glow plug terminal. Have an assistant keep time while you watch the tip of the glow plug.
12. Connect the wire coming from the negative terminal of the ammeter to the positive terminal of the battery and start counting. Pay close attention to the ammeter needle and the tip of the glow plug. The tip of the candle should heat up to red in about 5 seconds. After approximately 15 seconds, the current should drop from 25 A to 12 A.
13. Please note that the figures above are approximate. If the test current is close enough, the spark plug is probably good.
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