Extra part on oil pres switch...?


New Member
Dec 8, 2003
San Diego, CA
When I swapped my car's 4 cyl for the 5.0, I added a autometer oil pressure gauge and sending unit. Now I'm pulling it out and going back to the stock gauge. I bought the oil pressure switch from Autozone but I think I'm missing something. My brother recently did the same thing... he robbed the sending unit from a bone stock motor we had laying around and it had some kind of additional voltage regulator (or something) connected to it (between the sending unit and the harness) and I'm wondering what it was and if I need it... Anyone have any insight?
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there are two different types of oil senders. one is short (for the 4 cyl cluster, it is known at the "light type) and one whose body is a couple inches longer (for the 8 cyl cluster, it is called the "gauge type"). the difference is, the 4 cyl dash gauge has its needle stop at halfway to simulate gauge action. the 8 cyl dash gauge has full sweep.
Where in the harness are you talking about? At the OP sending unit itself, there's just one wire that goes on top of the sending unit, IIRC. The voltage regulation (on fox III's atleast) is at the gauge cluster.

Good luck.
I'm talking right on the sender... My autometer sender had nothing extra, but the last stock sender I saw has an extra piece. This peice had the end that pushes onto the threaded rod on the sender itself, then a short wire going into a large rubber encasement (about the size of a bic lighter) and then it plugged into the harness. IDK, I actuallly don't remember my stock one (before the autometer) having this, but I know when we took the other one off that spare motor we were sure to keep that extra piece with it... I just wanted to make sure I wouldn't damage the gauge in my new cluster by not using this piece...
Anyone else know anything about this? I guess maybe I'll just go without and hope it's right...

I do!!

I have to go back into the memory banks for this one, but when I bought my '88 new back in the day (I seem to be saying that a lot these days) the oil pressure gauge was reading way too high without actually having such high oil pressure. I brought the car back in and the installed a resistor between the oil sending 'can' and the wiring harness that seemed to fix the sweep of the oil pressure gauge. The part itself was listed in a TSB at the time, not sure if you can find that info or not. Not having it certainly didn't "hurt" anything, but having it made the gauge more useful.

If noone responds with a part number I can look under my hood tonight and see if there is still a number if you need it.
yeah seijirou, probably....we've all seen them so that's probably it. I also recall the extra wire being doubled up back against it with one of those old-school looking zip ties with big square holes rather than the typical type.

and DucatiRdr, thanks! That's extremely helpful... I'll connect it straight up and report my results...