Low pressure of oil can testify from necessity of repair of the engine. The control lamp of pressure of oil serves for the alarm system that pressure of oil dangerously low. Even the manometre on a combination of devices shows only relative pressure. Pressure of oil is necessary for checking certificated mechanical (not electric) a manometre.
The gauge of pressure of oil is established in an end face of a head of the block of cylinders from outside opposite to a drive газораспределительного the mechanism. Turn out the gauge and instead of it screw a tip of a hose of a manometre.
Connect to the engine a tachometre according to the maintenance instruction applied on it.
Start up the engine and warm up it to working temperature. Check up pressure of oil upon frequency of rotation of idling and at 3000 mines-1. If pressure below demanded, probably, the backlash in bearings of a cranked shaft is increased or the oil pump is faulty.