Engine Lubrication System Trouble in General: Inspection

Before performing diagnostics, make sure that the engine oil level is correct and no oil leakage exists.

Trouble	Possible cause	Corrective action
Warning light remains ON.	a. Oil pressure switch failure
	• Cracked diaphragm or oil leakage within switch	Replace.
	• Broken spring or seized contacts	Replace.
	b. Low oil pressure
	• Clogging of oil filter	Replace.
	• Malfunction of oil by-pass valve in oil filter	Replace.
	• Malfunction of oil relief valve in oil pump	Replace.
	• Clogged oil passage	Clean.
	< Ref. to appropriate wiring diagram in SYSTEM WIRING DIAGRAM article. > Excessive tip clearance and side clearance of oil pump rotor	Replace.
	• Clogged oil strainer or broken pipe	Clean or replace.
	c. No oil pressure
	• Insufficient engine oil (degradation, etc.)	Replace.
	• Broken pipe of oil strainer	Replace.
	• Stuck oil pump rotor	Replace.
Warning light does not illuminate.	a. Malfunction of combination meter	Replace.
	b. Poor contact of switch contact points	Replace.
	c. Disconnection of wiring	Repair.
Warning light flickers momentarily.	a. Defective terminal contact	Repair.
	b. Defective wiring harness	Repair.
	c. Oil pressure switch failure
	• Cracked diaphragm or oil leakage within switch	Replace.
	• Broken spring or seized contacts	Replace.
	d. Low oil pressure
	• Clogging of oil filter	Replace.
	• Malfunction of oil by-pass valve in oil filter	Replace.
	• Malfunction of oil relief valve in oil pump	Replace.
	• Clogged oil passage	Clean.
	• Excessive tip clearance and side clearance of oil pump rotor	Replace.
	• Clogged oil strainer or broken pipe	Clean or replace.