How to Troubleshoot a 6.5 Turbo Diesel Oil Pressure Switch

by Curtis Von Fange

The oil pressure switch on a 6.5 diesel is a multifunction unit. When closed it provides power to the fuel transfer pump, sending a signal to either an idiot light or an oil-pressure gauge on the dash. Problems with the switch can cause the engine to quit or run poorly.

Step 1

Open the hood and locate the fuel filter. Remove the two bolts holding the assembly to the block, and move it to the side. Removing the fuel hoses is not necessary. Look underneath for the oil switch. It is a small unit with a two-wire connector; it is screwed into the engine block.

Step 2

Spray the switch with some cleaner -- if it is oily or dirty -- and wipe clean with the rag. Gently separate the plastic wire-connector. Examine it for corrosion, dirt or loose wires. Clean and repair if necessary. Reattach to the switch.

Step 3

Locate a good ground connection for the voltmeter. Turn on the ignition and determine the 12-volt power supply by back-probing the connector. If there is no reading on the meter, check the appropriate fuse to see if it is blown. This test ensures that power is reaching the switch.

Step 4

Start the engine after determining the power supply to the switch. Back-probe the two leads on the switch, and verify that the switch is closing. Twelve volts are optimally entering and exiting the swich. If not, replace the switch.

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