Hello all. I'm Tim and I've been lurking around the forum off and on for around a year or so. I have a '96 F-150 XLT with every heavy duty option that was available. I'm usually the kind of guy that can figure things out on his own, but that isn't happening this time.

Last week I decided it was past time to do the oil pressure gauge mod, so I ordered a sending unit. When it came in, I got started. I bypassed the resistor on the back of the instrument panel (even went so far as to cut it out) and installed the new sending unit. When I check my "new" gauge's operation, it still works exactly like it did before. It sits right in the middle of normal and doesn't move. What in the world?!? Just to confirm that things are working, I removed the wire from the sending unit, which sent the gauge all the way down to "L". If there is someone who could point me in the right direction on this, I would certainly appreciate it. Thanks!

 

Welcome to fte.


Unfortunately, the factory gauge, even upgraded is no more accurate than a light.You will need to put an aftermarket mechanical oil pressure gauge in,

 

Hmmmm...I swear that I've read about people doing the mod and having a gauge that will fluctuate with engine rpm's. I guess this brings up the question why do the mod if not going to benefit me anything. I could have saved myself some time and money.

Thanks for the reply!

 

I've read about that mod somewhere myself but I just installed some aftermarket gauges instead. I never trusted the oil, temp or charge gauges at all.

 

The factory oil gauge is merely a test light of sorts...It turns on with 5-7psi.....

 

What sending unit are you using? What application is it for? I have this mod on my truck and the gauge fluctuates like a normal gauge.

Also you need to ground the wire to make sure it pegs the gauge.

 

I take it you have read the post and watched the video in this link:
https://www.ford-trucks.com/forums/9...ure-gauge.html

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Read the thread but skipped the video. I got the Motorcraft SW1547B sending unit. I'll be grounding the sending unit wire that jas88 recommended. I guess we'll see what happens. Thanks again, guys!

 

What will happen is the gauge will go half way and stop with the wire grounded.
I think I am going to buy a 92 gauge cluster and just use the oil gauge module out of it and see if it works then.

 

I tried that on my 94, and it does the same thing. only time it showed oil pressure was when the belt flew off, and the truck started to over heat. I have a cheap set of mini guages mounted to the right of the steering wheel,I used a hole saw, and cut into the plastic.

 

Your engine may have good oil pressure and its at the bypass oil pressure. With the engine warmed up watch where the guage reads, then next morning with engine cold, watch where it sits. There may be a little diffrence.

On my 89 F250 I did the mod to, I have weak oil pressure and the guage will move once the engine is fully warmed. I have since put a real oil guage in and at hot idle my oil pressure reads 15psi, rev it up and it will goto about 40psi and no higher. With the dash guage, it would show low side and go up to middle when reved up.

If you can, install a real oil pressure guage(one with the hard line,not electronic one) and watch what happens. I picked one up for around $10 and I keep is around as a test guage when I question a engine's oil pressure.

 

Not if he jumpered the 20 ohm resister properly - if he's got that right then the gauge should go to full.

 

I have my 20 ohm resister properly jumpered and with the wire shorted to ground the gauge will go half way up the scale.
I am going to bench test 4 clusters that I have in a few minutes to see what is going on.

 

The gauge sits in the same spot, hot or cold. Right in the middle of normal.

I even went beyond jumping the resistor, I completely cut it out. The only way current will get between the 2 points is through the wire I soldered in.

I may have to bite the bullet and install an aftermarket gauge, but I would prefer to have the factory one working like a gauge should.

Thanks again everyone!

 

May have a bad hi resistance solder joint.
Do you have a tachometer in the cluster?
I just tested two clusters (95 & 92) on the bench and both pigged the oil gauge when I grounded the other end of the resister.
Both clusters did not have a tachometer in them.

I will have to pull the cluster back out of the 95 to see what happen. Here is an image of the jumper I put on it:


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