Gauge Problems Please Help

[grimlock97]

First off Hi Everyone! I have been lurking for a long time but mostly been on jeep forum looking for answers, and this forum reading threads. I have a bunch of gauge problems and it's driving me crazy! I have a 1979 CJ7 with a AMC 258 i6 / 4.2l and a couple of other small mods, nothing major. When I got my jeep, all the gauges worked except the water temp gauge, so i purchased OE replacement gauges from discountjeep parts here in alabama, I got a new oil pressure gauge, new voltmeter (changed them for looks) I got a new fuel gauge and temp gauge. My fuel gauge still works as it should, my temp gauge is pegged hot when i turn the key on, stays there while running and stays there when i disconnect the sender, i have checked sending unit resistance and temp gauge resistance and all is within range, the gauges are brand new but i still tested according to john strenks page. On top of that, my oil pressure gauge bounces like crazy, while the motor is running, and the voltmeter and oil pressure gauge pulse when the motor is off but the key is on, I have tested all my grounds to the dash and used emory cloth to scrape away any excess paint or anything else on the grounds on the motor, alternator, and all other ground points, My volts are 14.9 at the alternator, the volt gauge shows this as does a handheld voltmeter. So I'm at a loss, why is my temp gauge spiked all the time and why are my gauges pulsing, I have noticed that my oil pressure gauge posts on back are different, the middle post is 12v switch and the passenger side post is sending wire, if i put 12v switch on any other post the gauge does nothing, i have also wired directly to a new fuse location for testing and still the pulsing, could my voltage regulator be shot? Sorry for the long post, i just need some help. Also on the temp gauge is my jumper/regulator from fuel to temp bad? if so can i make my own using resistors? thanks again

 

[Torxhead]

Are you using aftermarket oil pressure and volt gauges with oem sending units? If so they may not be compatable.

 

[grimlock97]

I"m using the omix 17215.04 for oil and omix 17215.03 for Volts, it says they are factory style replacement gauges, same on the fuel and temp gauge, Also, the sending units for both appear to be relatively new and not original, i know before i got the jeep someone had done a full frame off restoration about 8 years ago, so most everything is updated, between the frame off and my ownership a college student bought it and practically destroyed it, so i'm just fixing everything on it. i can get new sending units if this will help, i was planning on it anyways, but i'm sure that's not the problem with the voltmeter because there is no sending unit and the problem with the temp gauge doesn't bounce it's just pegged high when power is applied, even with the sending unit unplugged. Thanks again for the help

 

[Old Dog]

I"m using the omix 17215.04 for oil and omix 17215.03 for Volts, it says they are factory style replacement gauges,

Try a different brand, omix has really bad stuff.

 

[Torxhead]

Another thing you might want to check would be the wiring, as in there might be a short somewhere.

 

[grimlock97]

thanks, i hate to know that i wasted 40 bucks on two new gauges, but i think i have a couple of old autometer phantom gauges laying around, i can try those and see if they still bounce all over the place, the main reason i changed my factory oil pressure gague was because it was bouncing too, just not the volt meter, I still can't seem to figure out the temp gauge, that is my biggest concern, i would love for that to be working!

 

[Torxhead]

The info that John Strenk has put out for the CJ gauges is the best that I have seen. There is also an updated page that he has recently put out also. If you need to know coolant temp and can't quite understand Johns post, I would suggest a mechanical gauge as a permanent or temp solution. I also have a collection of parts laying around that I should'nt have purchased.

 

[jasonmark1993]

Sounds to me like the sender wire for the temp gauge is grounded.

Or you have a ground wire hooked to the sender terminal on the back of the temp gauge.

Wonder if the gauges may be marked wrong. I can't think of any gauges I've used that it wasn't sender in the middle and pos and neg on the sides. Sounds like you might have the pos wire hooked to the sender terminal on those ones that are bouncing.