Truck gauge swap woes
 

Alright, I have swapped my gauges and gotten everything working in my 85 xcab/4wd truck, except the oil pressure. Swapped in the full gauge setup with speedo, tach, voltmeter, etc. I knew about the oil pressure switch situation so until I had the correct sending unit, I left the wire unplugged. I purchased the oil pressure sending unit from Napa. The new sending unit has the nub on the end where the wire slides on, but it has a small tab on the side as well where something else should attach. I get nothing when hooking up the wire to either of these connectors on the sending unit. Is there another wire that should go to the extra connector? Or what gives? Is my oil pressure gauge bad? I would think that an oil pressure sending unit would need some sort of power as it is not mechanical so should there be a power lead going to the extra connector?

oil sender
 

The wire should just plug on to the nub. Did you use any pipe tape or sealer on the threads of the sender? The sender must ground through the block by the threads, saler or tape might not let this happen. The sender is basically a variable resistor, as the oil pressure changes the resistance of the sender changes and the needle moves. HTH

Hey, thanks for the reply partszar! Nope, didn't use anything on the threads. This is actually the second sender I have tried, initially I had a used one I got from someone on the internet, it didn't work, so I figured what the heck and bought the new one. Same thing. The one I bought had a note in the computer system at Napa - "for Yazaki". The guages I have say Yazaki on the back, so I assumed this would be the correct sender. Looking at some places online now, it looks like the most commonly used one is a "Denso" type. I can get that one at Napa. Would there be a difference between the 2 of them? I just don't get why the new one has an additional connector (for like a spade type connector you'd use for hooking up speakers, etc) sticking off the body...

sender
 

I didn't know they had two different styles, I justlearned something new. If you have access to a multimeter, I'd check to see if the sender is working. Set the meter to ohms, disconnect the wire from the sender, start the engine, touch one probe from the meter to the center nub of the sender touch the other end to ground (engine block) see if the resistance changes as the engine is idling. If it does the sender is probably good and you have a wiring problem from the sender to the gauge. HTH