1. Check the flash alarm first. As for the short-circuit flash alarm, if the lubrication oil pressure is low, the signal shall be given from the low terminal contact to confirm that the signal circuit is normal.

2. After the low contact of lubricating oil pressure in the lubricating oil pressure protection is switched on, a relay will be started, then the relay acts, its contact shall be closed to give the signal that the lubrication oil pressure is low. Check whether the relay contact is well connected or not. 

3.Check the line.