Glow Plugs — Checking (Mitsubishi Colt 4)

When checking the glow plugs, the battery must be fully charged, its voltage must be at least 12 V. The engine is cold.

If the temperature is above 55°C, disconnect the coolant temperature sensor connector.

The power supply can be checked without removing the glow plugs. To do this:

Connect the voltmeter to the glow plug current bus and to the glow plug body.

Turn on the ignition and warm up the engine (preheat). The voltmeter should show battery voltage (9 V or higher) for a few seconds.

After starting the engine, let it idle. During and after starting, the voltmeter should show battery voltage (9 V or higher) for several minutes.

If there is no reading on the device, the preheater control unit must be checked.

Checking glow plugs consists of the following:

Check and clean the current busbar from corrosion or replace it.

Check the glow plug for visible damage.

Disconnect the connection wire and the current bus.

Measure the resistance between the glow plug contact and the spark plug body. The required value is about 0 Ohm. If the resistance is infinity, replace the spark plug.

Also check all glow plugs.

Connect the wire and the current bus.

If disconnected, reconnect the coolant temperature sensor connector.

If the engine continues to have trouble starting and no fault is found, the injectors should be removed and the glow plugs should be observed through the holes.

Glow plugs with burnt heating rods cannot be simply replaced. In this case, the injection nozzles must also be checked for injection pressure and tightness.