I am putting a 90 instrument cluster into a 87 F150. All gauges work except the oil pressure gauge stays at 0. I tried two different clusters with same results. Old oil gauge worked, so wiring should be fine. I replaced the oil sending unit as the wiring diagram showed a 22 ohm resister in the 90, but that didn't help. Tried jumping the resister and that didn't help. What else should I do to get this gauge working.

Thanks

 

The guage in a 90 panel isn't really a true guage. It's a glorified idiot light. The oil sending unit is really an on off switch. turnson at 7psi and above. off at 6 and below. the 20 ohm resistor is to put a load in the circuit so the needle swings up. There is a thread about this guage in the 87-96 trucks and vans forum titled "what does your oil pressure guage read". I am sure there is a little more info there. I don't know if your 87 read as a real guage or not. My 84 did. the 90 will not. you might want to try a sender for a 90 300 I6. it will not show true pressure. My guage in my truck (see below) works this way. as long as there is approx 7psi the needle will swing up. my needle has always read between the A and the M in the word normal. In the thread i mentioned before there is a link to another site that tell you how to modify the guage to read true pressure. I hope this helps you Backally.

 

>The guage in a 90 panel isn't really a true guage. It's a
>glorified idiot light. The oil sending unit is really an on
>off switch. turnson at 7psi and above. off at 6 and below.
>the 20 ohm resistor is to put a load in the circuit so the
>needle swings up. There is a thread about this guage in the
>87-96 trucks and vans forum titled "what does your oil
>pressure guage read". I am sure there is a little more info
>there. I don't know if your 87 read as a real guage or not.
>My 84 did. the 90 will not. you might want to try a sender
>for a 90 300 I6. it will not show true pressure. My guage in
>my truck (see below) works this way. as long as there is
>approx 7psi the needle will swing up. my needle has always
>read between the A and the M in the word normal. In the
>thread i mentioned before there is a link to another site
>that tell you how to modify the guage to read true pressure.
>I hope this helps you Backally.

I did replace the sending unit with one for a 90 300 I6, but that didn't help. I would have thought that would have done it. Anything else other than put in an aftermarket? I would prefer to stick with the stock gauges.

 

[updated:LAST EDITED ON 14-Dec-02 AT 10:58 AM (EST)]Get a multimeter and test each component: sender resistance with engine on vs. off; wiring from sender to cluster; voltage of each terminal of gauge with key on & cluster plugged in. The oil gauge is actually the same as the fuel & temp with a different face screwed onto it - you can swap them around to test them. The voltmeter is different.

BTW If your original cluster didn't have gauges, that's the problem. The wiring is different.

 

I did this to my truck, it worked fine, now the oil pressure actually changes! I took the cluster out and jumped the 22-ohm resistor, cut it off and put a piece of speaker wire in its place. Next I bought a PS-60 oil pressure sending unit at Advanced Auto, the sending unit doesn't look like the original(this scared me because I did not know if it was going to work), the PS-60 is all metal about 1.5" long and 1" diameter.

hope this helps.

 

Do you know know what that sending unit came off of? I called Advance Auto and they said that PS60 is a invalid part number.

 

Forget the last message. Got it working. Had to change the position of one wire on the plug going into the cluster, soldered in a bypass for the resister, and got the PS60 sending unit. Works!! Advance auto was no help on the sending unit, but Autozone did a cross reference and came right up with it.

Thanks for the help, guys.