Bjorn20

I'm working with a 00 z28, did a ls6 manifold swap over winter and just noticed the oil pressure gauge pegged far past 80 psi (key on engine off, and with engine running). This is with an Oreilly sensor. I destroyed the original one during the swap.

Did some searching, some say its a sending unit problem, others say its a wiring problem. I got the sending unit out and the terminal was all bent to ****. With it unplugged and not threaded into the engine, the gauge is still pegged out? You could wiggle it a hair back and forth before removal. I already have a sending unit on order but don't want to put it in (probably wont be able to return it) and not fix the problem. I do not even know how I got the connector to plug in with that terminal bent at a 45 degree angle.

The connector and wire look good. I don't see how it would even be getting a signal at the dash if that wire (power source) was bad. Unless maybe a ground? On a wire diagram is shows that it has a ground (RF of engine/LR of engine). Is the ground for the sending unit bolted to that bracket (houses 2 of the rear intake bolts) on the driver side rear of the engine? It seemed pretty snug.

In working condition, isn't that gauge supposed to read 0 with "key on engine off" ?

thanks.

Bjorn20

I just plugged in a new sending unit from Oreilly and the gauge is still pegged out with key on, would this be a ground issue then?

88gtman

Sounds like it to me. Check all the wireing from the connector to the OSU back and see if there are any shorts or area where the insulation has been torn. Sounds like something is going on with the wires.

mike171562

iTrader: (4)

make sure Oreilly gave you the right OPSU, they gave me the wrong one initially and had to special order the correct one.

Bjorn20

I probed the connector with a test light and I have power. Was able to remove that wire on the back of the driver valve cover and I have a signal for a ground but the signal is very faint, barely lit up the test light at all, so I'm guessing thats the problem. I hate wiring.

Don't understand how this wire magically lost its ground connection after the intake swap? That harness is too far back to even be in the way of the intake but w/e, have to start tearing that up.

I've also heard of the needle's in the cluster assembly get all messed up if the battery was left connected during a job, and you gotta take the whole lens assembly out and move the needle back manually or replace the cluster. But I'm pretty sure I had the batter disconnected during the swap.

OldCobraGuy

iTrader: (2)

let's see if we can help you understand the way this works.

Without a ground, the resistance is high and the gauge in the car pegs. You have noticed that. There is no wire to ground that sensor. Dumb, I know and it makes it hard to remotely locate the sensor. So the sensor grounds through the block. Hook up your new sensor without installing it, run a lead to the metal sensor body and ground, and your gauge will show accurately. Once you show that, go ahead and install your new sensor and you should be fine.

Bjorn20

^^^ you are correct sir, here I am messing with a ground wire that didn't even pertain to that sensor. I was honestly going to start ripping that entire harness apart and splice in a new wire for a better ground, thank god I didn't. Apparently that wire in the back is a ground for the fuel gauge, which I discovered when my fuel gauge dropped to "E" after removing it.

Thats what I get for looking at the wire diagram wrong. I threaded that sensor back into the motor, plugged it in correctly and walla the oil pressure gauge reads "0" now like it should

So for anyone trying to mess with that sensor blindly without taking the intake back off slightly, be careful plugging the connector in, even though the plug did "snap/click" into place, it was off-course to the terminal and bent the **** out of it, resulting in a non connection.