I’m replacing the oil sensor. Found out somehow previous owner cut the wire pigtail. It’s four prongs for the sensor but the wire harness I bought has three wires. The wires off the harness from the top of the engine only has two wires. Am I missing something? Which wire does what?

 

What year car are you working on? Your profile says you own a 1993 Z28 and that would have two oil sensors, one for pressure and another for level. Which sensor are you referring to?

 

My bad. Meant to say it’s a 96 3.8. It’s a car I’m working on for someone. It’s the sensor right next to the oil filter. The lines run in front of the block, tucked down behind the pulleys. Looks like maybe the belt broke and ripped it or someone pulled the wire to hard.

 

The illustration I found shows two going to the oil pressure sensor.


However, on the Instrument Panel schematic it only shows one tan wire going to the oil pressure sensor. This would makes sense because the sensor is just controlling the ohms for a signal to the oil pressure gauge using a variable resistor connected to a engine block ground. Is it possible that the harness to the Camshaft sensor was also damaged and that could explain why you have extra wires? What are the colors of the wires from the engine harness?

 

From the Instrument Panel schematic I interrupt the drawing to represent the oil pressure sensor is grounded through the sensor body mounted in the engine block. I suppose it could be possible that the sensor ground could be the second wire. I'm skeptical of that fact because that is not what is shown on the schematic. Notice how the oil level sensor is drawn above. It clearly shows a wire used for the ground. Here's how the service manual describes the operation of the gauge.

 

I found the connector diagram below for the oil pressure sensor that shows the connector having four terminals. The Instrument Panel drawing above shows only the tan wire connected on terminal "A". Not sure what terminal the second wire would connect to.

 

The wire pigtail u circled is the one I have to replace. The one I purchased has three wires for it tho. It will work but I’m not sure what wire to eliminate so it will work with the new sending unit. I know the stock has four prongs and I have a four prong to go into it. The pigtail three wire is throwing me off. I also have a two prong sensor. Just left the pick and pull to see if I could score one there but they were all missing. So back to the task of figuring out which wire is what. Also on the new pigtail they have all three wires the same color. I’ll take a pic once I get to the garage.

 

Use the connector drawing above and find the lead connected to terminal "A" with a continuity tester and connect it to the tan wire of the engine harness.

 

This is what I ended up with

 

Black and Tan are the wires on the engine. I totally forgot to say that.