Jeep CJ Fuel and Temperature Gauge Problems and Testing 

Thanks for everything. Over the past two years restoring my 79 cj5 I have gone from clueless to mildly competent thanks largely to your great videos. My daughter will be driving in a year and she wants the jeep. It is you that is giving it to her

A friend of mine ask me to watch this video and this is the best quick test of the OEM fuel gauge. Using the test light is the best way to run a quick test of the fuel gauge. I've been seeing more and more of you videos pop up and really like them.

Mines hasn't worked in 8 years. This video will help me get mine working. Thanks for your help.

What a cool and helpful guy you are! My better half rolls her eyes every time I add another piece of blue tape with the new "do not exceed" mileage to the speedo. You've taught me now how to properly diagnose this. If I do trace it to the sending unit, that blue tape method might just have to be the solution though with so many rusty bolts attaching the skid plate to the gas tank!

I guess I'm one of the lucky few that all of my gauges work when I found my 77 CJ7. I now daily drive it after a few years of restoring it. I love it!

Just watched video , excellent , ALL your videos are super gelpful. You are right to the point and explain it step by step . I use your videos all the time and very helpful. .

this video rocks. helped me solve my fuel gauge issues. realized that my original sender hasn't been grounded due to a change to rubber fuel lines. now i just have to figure out how to add a ground....

Happy New Year ! Oh and yes , cool sweater 👍 . I’ll say I jumped the gun as I put myself in the position that time was of the essence . Not a smart thing to do on my part , but consider the source 🙃 . If I had actually physically inspected a bit more , I would have found road dirt and corrosion on a rear harness disconnect by the left rear tail light and maybe the original gauge may have worked and possibly been fairly accurate ? Well , I opted to replace both cluster gauges , fuel and temperature since I wasn’t getting a reading on either . I did have voltage but decided to pull the trigger anyway . Being of sound mind and somewhat of body , I pulled the tank and reinstalled it with a new sending unit . That proved to be a necessity . Plenty of corrosion and not a lick of ground . The sending unit was worse for wear and didn’t give such a clean response on its scale on the ohm gauge . I may have screwed the pooch with the dash gauge as both gauges did ohm out fair . It would have proved interesting using an OMIX Ada sending unit with an OEM 5 volt fuel gauge . Accuracy is questionable so I’m always asking myself how much gas do I think is really in . As far as the gauge working , if I remember , the temp gauge pegged and I had to reverse the polarity by reversing the jumper connection . It’s actually a year and a half ago I did the job but I’m reasonably sure it was the temp gauge and not the fuel gauge that had the polarity problem . OMIX Ada tech was very helpful and was aware of then manufacture problem . They graciously offered to replace if was found a problem . Once the polarity was reversed , all was well . Can I say the temp gauge is accurate ? Well , looking at the scale which just has a C and an H and a line in between , it’s old school all over again. No digital so no accuracy in that respect . As you note in the video , make,darn sure to find that connection and clean it if hounding to get a proper signal to / from the sending unit . Of course we would 😊 . Will I venture to drop the tank and experiment with the sending unit for accuracy ? I’ve been meaning to . There were better mopar units , fuel and temp but I don’t think as of this date are available . Not cool but just typical .

Great video. Great troubleshooting so much better than just throwing parts at it

Thanks for the help learned a lot from you now my oem gauge’s working after 30 plus years right on Ps need more cool guy videos

Thanks for the video, very helpful since I've been procrastinating on checking my fuel guage and sending unit. I'll fill the tank until fuel spills out but the needle never gets all the way to the right/full side. Then I'll drive it until it reads empty but keeps on running for several more days. I know the 15 gallon tank was replaced with another 15 about two years ago but I'm not sure about the sending unit or the gauge...I think they are still original.

Nice detail, thank you!

I accidently put the hot wire in the jumper piece (A) and now my gauges need to be replaces :( , Cool guy thank you for your videos it makes life easier!

Thanks so much for the video it helped me out a lot.

A very very nice car, from bottom to top, inside out, clean and shine..👍🏼👍🏼👍🏼

Great video! I just picked up an '83 CJ-7, and the speedometer works, but the temp and fuel gauges, along with the lights, do not work. I haven't tested the connections yet or taken apart the dash.

Been looking forward for this one! My 75 gas gauge is reversed,full on left, and empty on the right,guess that’s a 75 and earlier model thing?

Nice Golden Eagle

Good video. I have 2 driveable cj5. They both have problems with the gauges

Very helpful! Thank you!

I bought a crown coolant sending unit. It was doa. Bought a amazon mexican made one and it seems to work fine. Idk what brand fuel sending unit i have but its aftermarket and works. I have the original, but replaced it when my old gas tank rotted out. Dirt tends to sit in between the skidplate and rust from the outside in.

Does your voltmeter function? I disassembled mine and have noticed then when I hooked to my power supply that the magnet does move and the needle is not fixed to it, I was wondering if it originally was and if a small dot of superglue could solve the issue. Any feedback would be great, love your channel I bought my 81 cj last March and am loving it!

Hi. Really good video. I am about to replace My cj5 77 fuel gauge. It's better and safetier to work with all the things out of the car (over a table). Thank you

Great video as usual! Also, very timely. I’m just putting the dash back in my 1976 CJ7 and had the speedometer installed. I took it out to do these tests just to be sure the gauges are good. So, I am getting all of the correct Ohm readings from the fuel and temp gauges. I also did the 12v battery test and both gauges take power. But, when I tested for continuity between the fuel gauge “I” post and the speedometer housing I don’t get a tone. Is there a way to check the ground or clean the contacts? Any help is really appreciated!

On my ‘77 CJ resto, swapped sending unit with a crown and it was DOA. Swapped for a different one and it worked. Now 6mo later it still works, but may or may not got the FULL when I top tank off. :(

Good video, but a couple of things, you need to hand adjust your sending unit on the bench before installing it, by bending the arm. The sending unit is rarely correct from any manufacturer (legally they cant be) unless its oem . This is done by using your ohm meter and testing it at empty versus full, you will need the shop manual to get the correct resistance at the desired level (61 ohms empty, 23 ohms half tank, 10.3 full for 1981). If your still not getting the desired reading on the gauge you will need to remove the gauge from the housing, use alligator leads to make the connection and in the middle of the gauge back side there's a tiny hole with an adjuster screw which will allow you to dial it in, flat tip screw driver.

Great video I just picked up my first jeep at 60yrs young had mostly muscle cars through my years you said you have a wiring diagram for the 79 CJ7 which is what I just purchased and look forward to many of your videos to come I don’t see an email address to send to you my request for it. Can you tell me how to get in touch with you? 🙏🏻

Hey bud, like all your videos. I have a 86 cj7 with some really screwed up wiring. All my exterior lights work as they should but no dash lights at night, also the last guy that owned this jeep, replaced the speedometer. Did not connect anything to it but had installed a separate gas gauge, that does work. I noticed I don’t have the jumper wire from A to temp gauge on this. Is the new ones different or do you know ? and also my ohm readings were very different than yours. Any thoughts? Thanks for any help. Also you would not have any diagrams of the light switch by chance would you?

i usually just count KM. can get ~250 km to a full tank but driving over bridges etc gets scary when the gauge is at 0. maybe when i get the time i'll try out your tips thanks

Hey so what if the ohms readings are too high when tested from say S and to ground? Does that mean the fuel gauge is bad? I'm trying to get mine to work and get solid test light on I, flashing on A and dimmer flashing on S when the wire is disconnected, with the S wire connected the light flashes very very dim and the fuel gauge only moves to about 1/8 tank. Sending unit Ohms are 15 which should be accurate since the tank should be almost full.

Hey. Pretty good video! Question for ya….. With my ACC on, I tested the wire in the engine compartment going to my temp sensor. Mine is a constant light and not flashing. Thoughts on this?

Where do you get all your Cj parts at? Ive receive my dad’s old 86 Cj, and i REALLY wanna fix her up although 20 years of Florida humidity ruined a lot.

Hey bud how are I have a 1983 cj7 i replaced the fuel & temp gage they work out side the dash but I install cluster in dash they don’t work

So I have a question. I just recently installed a brand new sending unit and gauge worked fine for about a month then became stuck on half a tank. I dropped the tank and checked the sending unit and it was good. Then followed your directions to check the gauge itself. Everything seemed to be working fine yet my gauge is still stuck on half. What could be my issue?

I had an omix dead on arrival… the post was grounding out on the housing… only has a tiny cheap little oring isolator… was bad. Second replacement unit ohms bounces… 2nd dead on arrival as well..

Well I have the main power to the gas gauge and then the two posts that go to the coolant gauge both blank but when I try to put the test light on the sending unit wire nothing happens. Also, my engine block temperature sensor does not flash any light when I put the light meter on it. What does work though is if I turn the key on and I put a ground wire to the engine temperature sensor wire it makes the coolant temperature gauge needle go to hot.

I did the quick voltage check on my temp gauge to see if the gauge would move. It moved the opposite way … more toward cold??? Any ideas? I had the wires just like you showed. Thanks, Rock…. 78 CJ5

When testing continuity from the posts on the back of the fuel gauge to the speedometer housing, I have continuity from S, A and, I. Is that bad? I have a spare speedometer and that one has continuity from the S post only.

Again thank you

Okay, so S isn't flashing with a test light on the fuel gauge. When I removed the wire from the sending unit "S" it starts flashing. Does that mean I have an issue somewhere from the sending unit to the cluster?

My gauges work intermittently. If I put the test light on the sender post of the temp or fuel gauge, the gauge read, but I am guessing they are just reading the resistance of the test light circuit? I know my fuel sender is not grounded (waiting to burn through this tank of gas to drop the tank), but I can't figure out the temp sender...

I tried the alligator clips on the back of the fuel gauge while it was still in the dash. Got nothing. It still should have worked even though it was still hooked up right?

When testing the temp gauge should you not be hooking up the positive to the positive on the fuel gauge to see if it goes through the by metal

I am not getting a continuity sound when I go to make sure my fuel gauge is grounded to the housing.. what are my next steps? Why wouldn't it be grounded?

I need to replace the fuel gauge. Do I have to take out the entire speedo cluster to do this? If so do you have a video showing how to remove it? Thanks!

My question is. How do you keep the gauge at full? I drive around town and it goes to E.

i believe you may have a test wrong when measuring the +5 DCV . i would think you want to go to ground and and jumper going from the fuel gauge to the temp gauge. Putting the leads of the volt meter across the jumper wont read the voltage because one of the leads needs to go to ground.

hi! any way to add rpm gauge to base 1980 cj5?

I got my 1980 CJ5 back from a friend's shop. I had put in a new fuel sending unit. The tank is a poly 15 gallons. I never had a full tank, just maybe 5 gallons in it. Sometimes my fuel gauge needle will bounce a little, but not much. 2 days ago after I added about another 4 gallons of fuel by hand, when I start the jeep the gauge goes from before the E to on the E . When I turn key off, the gauge needle goes to before E. I am pretty sure the fuel gauge is working, otherwise it would not move. What should I need to look for, check the ground wire on the sending unit, drop the tank and check the float arm on the sending unit? Maybe see if it needs to be slightly bent? I did calibrate with my multimeter, and moved the arm and it read 72 empty and 10 full. When you said about the speedo cluster being grounded, is that with it in the dash, or does the speedo need a separate ground wire? Hopefully it is something simple. If you have anything to add let me know. Thanks so much. Your videos are very informative to all us jeep novices. I was wondering how to send you a video of my gauge before and after I start the jeep if you need to see it. Thanks Mark Feuerherdt

I had a quarter of a tank reading mine is empty why is that

Do you have anything on getting the oil pressure gauge to work?

and your suggestion for a replacement sending unit is....?

👍👍🇺🇲

I’ve come to the conclusion that it’s either the pink wire or the gauge itself. I’ve dropped the tank and replaced the sending unit and cleaned the ground connection.

What gauge wire size are they for wiring the sending unit and gauge?

@coolguy..bro I'm nervous.. so it's ok to send 12v to the "I" post on the fuel gauge? I have a painless wiring kit I'm working on.🕵🏻‍♂️🤷‍♂️🥸 Just don't want to burn up the new gauge

Because of this this video, I had to subscribe