Car glow plug relay

How to detect the glow plug relay failure

Malfunction of the glow plug relay is simple to check on your own. For this purpose you need a multimeter or a test lamp.

You have to connect the tester probes or the lamp contacts to the relay control pins and apply 12 volts to it. If the relay is operating correctly, the lamp will light up and the tester's readings will change. Besides, you will hear a distinctive click. Absent light from the light bulb, no click and the unchanged tester readings indicate that the relay contacts do not close.

After that, switch the multimeter into resistance mode and measure the resistance between the relay coil winding pins. If the gauge shows a breakage, the component requires replacement.

Two-stage glow system relays are installed on many modern cars. In this case, you should test the resistance between the two pairs of control contacts as described above.

You may identify that the glow plug relay requires to be inspected by the following symptoms:

• there is no click when you turn the key in the ignition lock during the cold season;
• the glow plug indicator light stays on or does not turn on;
• the on-board computer signals an error;
• the engine starts with problems at low environmental temperatures.

Causes of the glow plug relay failure

In most cases, the failure of the relay is due to violation of its housing tightness and the ingress of dirt and moisture inside the relay, which causes the contacts to oxidize. Besides, accumulated deposits can lead to jamming of the movable armature. In such a case, the relay control contacts do not open the circuit even after power is supplied, which results in their overheating and burning.

Dirt, moisture and high temperatures are hazardous for the relay winding too, since they have a disruptive impact on its insulating layer and can promote coil-winding short circuit or breakage of the turns.

Quite often the component overheating occurs due to mechanical wear of the movable contacts, because of which their connection reliability is broken or due to cracking of the connectors.

If the relay fails too often, you have to check if the voltage is stable in the electrical circuit, and if the component parameters comply with the car technical requirements.

Repair and replacement of the glow plug relay

Sometimes the component performance can be restored by cleaning the contacts and tightening the fasteners. But usually the relay is subject to replacement. You can install a new part on your own. For this purpose, use the following instructions:

1. Turn off the ignition.
2. Disconnect the negative terminal from the battery.
3. Unscrew the ECU cover lid bolts.
4. Remove the lid.
5. Disconnect the wire harness from the relay.
6. Take the part out of the seat.
7. Install a new one in its place.
8. Diagnose the system.