Engine Oil Pressure Indicator Flasher System Input Test
- Remove underdash fuse/relay box. See UNDERDASH FUSE/RELAY BOX under REMOVAL & INSTALLATION. Remove driver's multiplex control unit from underdash fuse/relay box. See Figure . Check driver's multiplex control unit connectors for loose, damaged or corroded terminals. If problem exists, repair as necessary. If problem does not exist, go to next step.
- Turn ignition on. Measure voltage between ground and underdash fuse/relay box connector terminal A13. See Figure . If battery voltage exists, go to next step. If battery voltage does not exist, check for blown fuse No. 13 (15-amp) in underdash fuse/relay box. Check for open in underdash fuse/relay box. Repair as necessary.
- Start engine. Measure voltage between ground and driver's multiplex control unit connector terminal B2 (White/Blue wire). See Figure . If battery voltage exists, go to next step. If battery voltage does not exist, check charging system. See GENERATORS & REGULATORS article in STARTING & CHARGING SYSTEMS. Check for open in White/Blue wire between underdash fuse/relay box and generator or gauge assembly. See WIRING DIAGRAMS . Repair as necessary.
- Turn ignition off. Check continuity between ground and driver's multiplex control unit connector terminal C5 (Yellow/Red wire). If continuity exists, go to next step. If continuity does not exist, check for open in Yellow/Red wire between driver's multiplex control unit and engine oil pressure switch. Check oil pressure switch. See OIL PRESSURE SWITCH TEST under COMPONENT TESTS. Repair as necessary.
- Turn ignition on. If oil pressure indicator light illuminates, go to next step. If oil pressure indicator light does not illuminate, disconnect oil pressure switch connector (Yellow/Red wire). Connect jumper wire between ground and Yellow/Red wire. If oil pressure indicator light illuminates, replace oil pressure switch. If oil pressure indicator light does not illuminate, check for faulty indicator light bulb. Check for open in Yellow/Red wire between engine oil pressure switch and gauge assembly. Repair as necessary.
- Start engine. Measure voltage between ground and driver's multiplex control unit connector terminal C5 (Yellow/Red wire). If battery voltage exists, engine oil pressure indicator flasher system inputs to driver's multiplex control unit are okay. If battery voltage does not exist, check oil level or improper lubrication. Check oil pressure switch. See OIL PRESSURE SWITCH TEST under COMPONENT TESTS. Check for open in Yellow/Red wire between gauge assembly and underdash fuse/relay box. Repair as necessary.