oil pressure sender wires?

[bad six]

When installing an autometer oil pressure gauge, what do you do with the factory wires from the oil pressure sender, the red wire brown, and grey, do you attach any of them to the new pressure switch and if so in what way, I mean do you attach two together and leave the other I am confused?

 

[forzfed]

You can run a "T" and hook up the idiot light or just tuck the wires neatly away.

 

[PaCemkr86]

 

[tb3]

What is the purpose of the third wire on the factory oil sending unit plug? I looked in my 87 service manual, and as far as I can tell, it parallel's with the fuel pump relay. Is there any negative side to not using that third wire when I install my oil pressure guage sending unit and delete the stocker? I understand I will no longer have a idiot light, and all will still work normal. but, again, any negatives about not using the third wire? thanks

 

[grocerygetter]

Cap off the wires though...you don't want 12volts bouncing around. I capped all three of mine and just ziptied them up on the valve cover.

 

[tb3]

Thanks, I'll definetly cap them. But is there any negatives concerning not using that third wire that is also in-line with fuel pump relay?

 

[turbofabricator]

Thanks, I'll definetly cap them. But is there any negatives concerning not using that third wire that is also in-line with fuel pump relay?

In a word, No. I usually install a tee in line, but it won't effect the way the car runs if you leave it unplugged. Mine is not even in the engine bay anymore. If you have a "hotwire" kit for the fuel pump (Which you SHOULD have) Then the oil pressure wiring has ZERO effect on the fuel pump operation.

 

[tb3]

many many thanks!!! I do indeed have the hotwire kit.

 

[mybuick]

the wire is there if the oil pressure goes below a certan point, the engine will shut off so it don't blow up.

 

[Jerryl]

What is the purpose of the third wire on the factory oil sending unit plug? I looked in my 87 service manual, and as far as I can tell, it parallel's with the fuel pump relay. ........

....... If you have a "hotwire" kit for the fuel pump (Which you SHOULD have) Then the oil pressure wiring has ZERO effect on the fuel pump operation.

Not sure about that.
http://www.turbobuick.com/forums/ge...ng-question.html?highlight=oil+pressure+wires

the wire is there if the oil pressure goes below a certan point, the engine will shut off so it don't blow up.

What I thought.

 

[turbofabricator]

Not sure about that.
http://www.turbobuick.com/forums/ge...ng-question.html?highlight=oil+pressure+wires


What I thought.

Well, if you wait for the oil pressure to reach the "shut-off point", it's TOO LATE! I have been running cars with it disconnected for 15+ years on MANY cars. It's NOT needed, unless you want an idiot light to tell you that you just grenaded your engine bearings. On my car, the wiring harness was trimmed and cleaned up and I completely removed the wires from the harness. It seems to run ok? With a hot wire kit, you are completely by-passing the oil sender loop to the relay, as the stock fuel pump relay is not used at all. (providing it is wired correctly)

 

[Jerryl]

Well, if you wait for the oil pressure to reach the "shut-off point", it's TOO LATE! I have been running cars with it disconnected for 15+ years on MANY cars. It's NOT needed, unless you want an idiot light to tell you that you just grenaded your engine bearings.

On my car, the wiring harness was trimmed and cleaned up and I completely removed the wires from the harness. It seems to run ok? With a hot wire kit, you are completely by-passing the oil sender loop to the relay, as the stock fuel pump relay is not used at all. (providing it is wired correctly)

Agree with “granading the motor” which is why most put in an aftermarket oil pressure gauge. I am still wondering why the factory and engineers wired the oil pressure switch to shut off the motor.

I am no expert, but it is my understanding (at least on my set-up), that the OEM fuel pump wiring is used to trigger the relay for the “hot wire”. Unless you do not use the OEM wiring to trigger, the oil pressure switch wiring will affect your fuel pump operation.

Sure one can bypass this “feature”, but in my mind, the difference between shutting it off below x PSI oil pressure and not shutting it off untill the engine stalls as a result of excissive friction, may end up to be the difference between "replacing bearings" and "replacing the block".

 

[salvageV6]

Some of you should read the service manual.

The oil pressure switch and wiring CAN'T shut off the engine with low oil pressure, unless your fuel pump relay and ECM are completely disconnected.

It's there to provide backup power TO the pump in case of ECM/fuel pump relay failure. Once you have cranked the car to build 4psi. it provides an alternate path for power to the fuel pump motor via Splice S115 which ties three wires together that go to the fuel pump motor. One from the prime connector one from the pressure switch and the third is the output from the fuel pump relay.

It's a high current switch powered from the FP/INJ fuse so make sure the wiring is capped off and can't short to ground.

The third wire runs the oil pressure idiot light switch to ground of the case and lights the bulb in the dash under 4psi. or so.

 

[tb3]

so turbofabricator is correct then about the hot wire kit being a good substitute for the alternate source of power should you lose fuel relay and aren't using the factory sending unit?

All I came up with in my manual was the print. My difficulty was in trying to figure out reasoning. (I think)

 

[tb3]

The above post was more of a statement, not a question. I've just unconfused myself, then reconfused. Hot wire kit is kind of a no brainer as being a alternate source of power as it has a lead direct to the harness from battery, however eliminating the factory oil pressure sender means no alternate source of power through the engine wiring harness.

"It's a high current switch powered from the FP/INJ fuse so make sure the wiring is capped off and can't short to ground."

This should make sensce to me, but doesn't. But I'm not worried about it at this point.

 

[salvageV6]

No he's not right.

You are.

This is correct, "however eliminating the factory oil pressure sender means no alternate source of power through the engine wiring harness. "

It's a parallel connection up front, there are many ways hot wire kits are installed and wired as well, most of them use the factory relay wire as a trigger wire, so without the switch in the oil sender the car will die if the power from the FP relay doesn't get to the hot wire trigger. It will keep running if the FP is over the required 4 psi. hot wired or not.

Some don't use the three wire switch, most don't know how it works either.

It's not that hard to keep on the car either.

If it shorts it takes out the FP/INJ fuse and the car dies, hence when disconnecting it proper care should be taken to cap it safely and securely, most that don't have it on there don't do that either.

 

[grocerygetter]

I found out about the 12v connection with the oil psi-inj-fp circuit through the wiring diagram pacecarta sent me when I was having fuel relay problems. You want that crap capped off and not bouncing around somewhere. Zip tie it off where you know where it is.

 

[Crammysauce!]

I realize I'm waking up an old post here, but I have a quick question -

What position on the oil pressure sender do each of the wires correspond to (colors and pin locations)? The entire front of my motor was left covered in oil so long by the previous owner that the harness connector actually melted into mush. I had to take the entire front end of the accessories off to do some work, and I don't think that I put the wires back on in the proper order, and now the engine won't run. If I understood correctly, I can just leave the wires disconnected and not have an oil pressure light. Is this correct?

Thanks!!

 

[turbofabricator]

I realize I'm waking up an old post here, but I have a quick question -

What position on the oil pressure sender do each of the wires correspond to (colors and pin locations)? The entire front of my motor was left covered in oil so long by the previous owner that the harness connector actually melted into mush. I had to take the entire front end of the accessories off to do some work, and I don't think that I put the wires back on in the proper order, and now the engine won't run. If I understood correctly, I can just leave the wires disconnected and not have an oil pressure light. Is this correct?

Thanks!!

True, but if you pulled the front cover off, then you will need to re-set the cam sensor. That is why it doesn't run. Check here for the instructions on how to set it. Vortex Turbo Buick Performance If your cam sensor is set correctly, then it might be the crank sensor. Search that site for instructions for that, too.

 

[mikestertwo]

The pink/black wire goes to pin "A", the grey wire goes to pin "C". These are the wires for the fuel pump. The remaining wire (can't remember the color off hand, getting old ), goes to pin "B", that's your idiot light.