Test I: Low Oil Pressure Indicator Inoperative/Always On

Turn ignition switch to LOCK position. Disconnect oil pressure switch 1-pin harness connector. Connect a fused 10-amp jumper wire between ground and oil pressure switch harness connector Red wire terminal. Turn ignition switch to RUN position. If oil pressure indicator light illuminates, go to next step. If oil pressure indicator light does not illuminate, go to step 3. If oil pressure indicator light is always illuminated, go to step 4.

Remove oil pressure switch from engine. Connect engine oil pressure gauge and adapter. Run engine until normal operating temperature is reached. Run engine at specified RPM and record reading. See ENGINE OIL PRESSURE SPECIFICATION table. If engine oil pressure is within specification, replace oil pressure switch. If engine oil pressure is not within specification, repair engine oil pressure concern. See appropriate ENGINES article.

ENGINE OIL PRESSURE SPECIFICATION

RPM	PSI (k/pa)
Idle	9 (59)
2000	60-65 (412-451)

Turn ignition switch to LOCK position. Disconnect instrument cluster 12-pin harness connector C266a. Measure resistance of Red wire between oil pressure switch harness connector terminal No. 1 and instrument cluster harness connector C266a terminal No. 4. See Figure. If resistance is less than 5 ohms, replace instrument cluster printed circuit. If resistance is 5 ohms or more, repair open in Red wire.
Turn ignition switch to LOCK position. Disconnect instrument cluster 12-pin harness connector C266a. Measure resistance between ground and instrument cluster harness connector C266a terminal No. 4 (Red wire). See Figure. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in Red wire between instrument cluster and oil pressure switch.
Disconnect all instrument cluster harness connectors. Inspect for corroded or pushed out pins. Connect all instrument cluster harness connectors. Operate system and verify if concern still exists. If concern still exists, replace instrument cluster. See REMOVAL & INSTALLATION . If concern does not exist, system is operating correctly at this time. Concern may have been caused by a loose or corroded connector.