The test is performed on a cold engine (ambient temperature) and a fully charged battery (output voltage not less than 11.5 V), the glow plugs must remain in their regular places.
Checking the power supply
1. Remove the powertrain trim panels.
2. Using a suitable tool such as HAZET 4760-5, disconnect the electrical wiring from the glow plugs.
3. Connect a test lamp between the spark plug wire contact and ground.
4. Turn on the ignition, leave the ignition key in the pre-glow activation position and watch the lamp - it should light up, confirming that the power supply to the spark plug is working properly.
5. Using a similar procedure, check the wiring of the remaining spark plugs.
6. Disconnect the test lamp and proceed to checking the spark plugs themselves (see below).
Checking the condition of glow plugs
1. Connect an ohmmeter between the spark plug contact output and the body to make sure there are no signs of a broken coil - conductivity should be present (resistance is not equal to infinity), otherwise the spark plug must be replaced. Proceeding in a similar manner, check each of the spark plugs.
2. Restore the original wiring connections and reinstall the powertrain trim panels.