How to Troubleshoot the Oil Pressure Sensor on a 1989 Ford F150

The 1989 Ford F1-50 utilizes two types of oil-pressure detection sensors. One operates the low oil-pressure red light on the instrument panel; the other operates a gauge and the light as well. Test both in the same manner. Three engines are available in the 1989 F-150: the 4.9-liter six-cylinder, 5.0-liter eight-cylinder and the 5.8-liter eight-cylinder Windsor. Both sensors are in the same locations. The sensor for the light is a small straight brass plug with a single wire. The sensor for the gauge is a much larger canister-shaped sensor with a single wire.

Instructions

1

Ensure that the truck has sufficient oil by checking the dipstick. Turn the ignition on without starting the engine. Look for the red low oil pressure light on the dash. The light should illuminate with the key on and engine off, since there is no pressure. If the light is out, open the hood and unplug the sensor wire. The sensor, regardless of type, will be just to the right and slightly above the oil filter.

2

Ground the sensor by connecting one end of the jumper cable to the terminal end of the sensor wire and connect the opposite end to the engine. The red low oil pressure warning light below the speedometer should illuminate. If the light fails to illuminate the bulb is bad. If it does illuminate, the sensor is bad.

3

Start the engine. The light should go out immediately if there is sufficient oil pressure. If it stays on and the truck has a gauge as well, look at the gauge to see if it is registering oil pressure. If it is registering pressure, the sender is bad. If it shows no pressure or the truck has no gauge, shut the engine off immediately. Do not let the engine run more than a few seconds to protect the bearings.

4

In the engine compartment, unplug the oil sensor wire on the top of the sensor located above the oil filter and remove the sensor with a wrench. Turn it counterclockwise to remove it.

5

Install the remote oil pressure gauge by threading it into the recess vacated by the sensor and tighten the fitting with a wrench. Start the engine and make note of the pressure. If no pressure shows, or very little pressure displays, such as below 10 pounds of pressure, shut the engine off immediately. The engine has an internal problem. If pressure shows on the gauge, replace the sensor.