I finally dug into my oil and volt gauges to see whats going on. I pulled the cluster twice now, checked,cleaned and tightened things up by tweeking the tabs a bit on the light holders and male harness plug. The oil pressure gauge works now, but when I turn on the headlights the oil pressure reading drops around 8-10 psi. Turn them off and back to 40 at 2500rpm. I never noticed before the temp gauge slightly goes up when I turn on the headlights. This leads me to a ground issue, however Ive OHM'ed the black lead which OHMs to 0 resistance. Oddly enough I found the PO or somebody used a scotch connector tapping onto the ground #3, and there is also evidence of one once on the black/white which I believe goes to the ECM. Im not sure what "normal" oil pressure is at idle and at say 2500 rpm but I seeing almost 0 and 40 on the upper end. I dont have much faith in these stock gauges for some reason. The temp,gas and clock work fine or seem to anyhow.
Nuther gauge question
- Thread starter Gilaguy23
- Start date
Having built 100's control panels I have learned a thing or two about wiring.
I hate Scotch-Loc connectors because they damage the wire cutting into the conductors.
I wince every time I see Scotch-bite on a wire.
While they're installed it's fine, but when removed, you may have only 1 strand making connection.
It will ohm out fine, but when a load is put on it heats up and becomes a resistor.
Chalk me up as another hater of scotchloks/t-taps. Junk that only cause problems.
If you unplug the oil sending unit, does the the gauge peg to 80? Definitely sounds like you have some ground issues with both gauges messing up when headlights go on. Especially since one goes up and the other goes down. They work opposite of each other, oil pressure goes down when it sees less resistance to ground, and water temp goes up when it sees less resistance to ground. Since they’re both going in opposite directions with headlights on, they must be each seeing less resistance to ground when you are turning the headlights on. Not sure why.
If you unplug the oil sending unit, does the the gauge peg to 80? Definitely sounds like you have some ground issues with both gauges messing up when headlights go on. Especially since one goes up and the other goes down. They work opposite of each other, oil pressure goes down when it sees less resistance to ground, and water temp goes up when it sees less resistance to ground. Since they’re both going in opposite directions with headlights on, they must be each seeing less resistance to ground when you are turning the headlights on. Not sure why.
Flyer58
YJ Enthusiast
Ha!Anything beats the old Lucas connectors but that's a different vehicle
Lucas Electric, the "Prince of Darkness"!
Not much a fan of anything British electric, but especially their metallurgy.
Seems like they built their stuff out of recycled Russian razor blades..
Arrrgggg...this is getting frustrating. Tore into things again this am and ran a second ground off the cluster ground lead to see what it did for the gauge dropping issue when the lights are turned on. It seemed to eliminate the issue 90%.
No, the oil pressure gauge does not go to 80 when grounded. If the sending unit lead is disconnected with the key on sends the needle to 60. This is where it sat for the last 2 years before getting the gauge working a couple days ago. Ground it out and the needle goes all the way down past 0 just like having the key off. For what ever reason it appears both the volt and Oil press gauges are reading much lower than they should. Volts always in the red at 8 to 12V and Its putting out 14.3, and the oil reading 0 at idle when it might be 20 at idle and 60,not 40 at speed Id hope. 2 bad gauges,I guess?? Im not wild about throwing in a bunch or aftermarket stuff, but now that I opened a can of worms Im bound and determined to get some accurate readings. Anybody have any comments on the Omix replacements?? Good, bad, inaccurate??
No, the oil pressure gauge does not go to 80 when grounded. If the sending unit lead is disconnected with the key on sends the needle to 60. This is where it sat for the last 2 years before getting the gauge working a couple days ago. Ground it out and the needle goes all the way down past 0 just like having the key off. For what ever reason it appears both the volt and Oil press gauges are reading much lower than they should. Volts always in the red at 8 to 12V and Its putting out 14.3, and the oil reading 0 at idle when it might be 20 at idle and 60,not 40 at speed Id hope. 2 bad gauges,I guess?? Im not wild about throwing in a bunch or aftermarket stuff, but now that I opened a can of worms Im bound and determined to get some accurate readings. Anybody have any comments on the Omix replacements?? Good, bad, inaccurate??
I asked about unplugged…which you said it goes to 60 when unplugged, but it should be pegging to 80. So definitely a wiring or gauge issue. The wiring being unplugged and the gauge only going to 60, not 80, is somewhat indicative of a bad gauge. But that’s the thing, if it’s a bad ribbon controlling all of your gauges, then that could be why they are all acting up. I don’t really know. Plus yours is a 91 which may not even have the ribbon? I’m not sure, not very familiar with 91- gauges.
Yeppers, it has the ribbon in back. Ive taken a magnifying glass and inspected every bit of it and see no cracks or flaws.All the lights work and all the gauges do work,albeit questionably on two of them. I wondering by month of mfg my 91 is different than what you've dug into. I cant see how the OP gauge would be completely opposite of how we thought it should work, and yet still function somewhat correctly. Im gonna have to toss around options for a volt and oil gauge. Im not wild about he plastic or copper tubing setups for a mechanical oil gauge.
Your OP gauge is functioning exactly how we thought it would - unplugged it should peg. It’s just yours is going to 60, not 80. So it’s not pegging all the way. Meanwhile the coolant shouldn’t peg if you unplug it, and it pegs if you ground it. OP should go to 0 if you ground it. Or maybe slightly below 0 like you said yours does. I’m not sure what the norm is there but I know it’s in the 0 end if you ground it.
I threw in a mechanical gauge today along with the factory one. 25 PSI at idle and 55 at rpm. Sure gives me a piece of mind seeing where it really is. In the process of digging around I found lots guys with XJ's complain about the volt gauge inaccuracy on that model. Problem apparently is poor wiring, lots of resistance by the time juice gets to the gauge and that what it really see's. Folks are running a relay set up and a power lead off the fuse box to the gauge and seeing the real alt output. Ive found similar issues on several of the motorcycles, from Harleys,Triumphs and a Ducati Ive owned over the decades. To many crappy high resistance connectors and undersized wiring for the charging system. Cure was to run a direct line from the charging system, add a Maxi fuse and go right to the battery. I typically would get a full volt more to the batt doing this than the high 12's or low 13's the factory stuff provided.