3.0L engine-Behind the right cylinder head, in the engine block. Picture at bottom.
2.9L and 4.0L engines-Left side front of the engine, below the cylinder head in the engine block
5.0L engines-Left-hand front of the engine, below the rocker arm cover
See Figures 1 and 2
Fig. 1: Oil pressure sender and gauge wiring schematic
Oil Pressure Sender
Use the accompanying diagnostic chart to help pinpoint oil pressure sender and oil pressure gauge malfunctioning.
Oil Pressure Switch
To test the oil pressure switch, open the hood and locate the switch.
Disconnect the wire from the switch. Attach one end of a jumper wire to the terminal on the end of the wire, then touch the other end of the jumper wire to a good engine ground (any bare metal engine surface). Have an assistant observe the instrument gauge cluster while you do this and tell you if the low oil warning lamp illuminates or not; the low oil warning lamp should illuminate.
If the lamp does not illuminate, skip to Step 3.
If the lamp does illuminate, replace the switch with a new one.
Before jumping to any bad conclusions, try a different area for grounding the jumper wire on the engine. If the lamp still does not illuminate, touch the jumper wire end to the negative (-) battery post.
If the lamp illuminates, the problem lies with the engine not being properly grounded.
If the lamp does not illuminate, skip to Step 4.
Connect the original wire to the oil pressure switch. While sitting in the vehicle, turn the ignition switch to the ON position without actually starting the engine. Observe the other lights on the instrument cluster.
If all of the other lights illuminate when turning the ignition switch ON, the oil pressure switch is defective and must be replaced.
If none of the other lights illuminate, there is a problem with power supply to the instrument cluster and gauges.
REMOVAL & INSTALLATION
Fig. 3: Oil pressure and level switches used on the 2.9L and 4.0L engines
Fig. 4: Oil pressure and level switches used on the 3.0L engine