jasoneggleston

The gas gauge and speedometer stopped working in my 94 Jeep Cherokee.
I was driving down the road and the speedometer and gas gauges started jumping. Then the gas gauge went all the way around past full and the speedometer is stuck on 0.

I had another gauge cluster. This one had come with the Jeep when I bought it but I changed it because the speedometer and odometer didn't work. The fuel gauge worked fine. When I plugged it in the gas gauge went all the way past full and the speedometer and odometer still do not work.

Any ideas what it could be?

A bad ground maybe?
I thought maybe it was the float in the gas tank but I don't see how that would screw up the speedometer too.

jd4x426

it could be 2 diiferent problems but i would start with checking grounds that seems to be a pretty common problem

FlyingLow

Check the grounds, and if the new cluster didn't solve it check the sending units.

jasoneggleston

Thanks for the quick reply.

I was just outside taking a look at it all.

How/where is it grounded? Is it one of the wires in the plug?

Where can I find a wiring diagram for the Jeep?

Sorry if the questions are novice but I am sort of electrically challenged. I can wire all the audio in the world but this other stuff is new to me.

FlyingLow

Grab a Haynes or Chilton manual from any auto parts store. They are life savers.

jasoneggleston

I have a Haynes manual in front of me now. Not sure what I am looking for though.

jasoneggleston

Okay.. progress maybe??

I found the page in the Haynes manual labeled "Instrument panel ground wiring diagram". I would have to assume this is the right page. Now to decipher it...

FlyingLow

Sounds right. Good luck

jasoneggleston

Not so easy finding the bad ground.

The page in the Haynes Manual was not the right page and I cannot find a diagram for the grounds.

There are 13 wires going to the plug that plugs into the cluster. Anybody know where I can find out what each wire is? Or more specific.. which may be a ground wire?

Is there any way to create a new ground without finding the problem.

jimmsy

I've had the same problem, but this is how i solved it. First of all, remove your instrument cluster. You will notice on the back of the cluster, a curciut board type of plastic laid out and secured by mounts and screws. You will also notice the sockets were the plugs fit into, one in the centre of the instrument cluster, which suplies info to your speedo, tacho, and gauges, the other plug fits on the side which suplies power and displays your warning lights , check engine status and 4 wheel drive mode. First thing you should do is clean the ciurcut board with a ciurcut board cleaner. Try not using something to harsh as it may damage the plastic which the circuit copper is mounted on. Your local electronic hobby store should have the appropriate cleaner. Remove the screws which are on the back of the speedo making contact with the ciurcut board. Clean these screws and the copper beneath them so you have a good contact between both surfaces. I actually did all the screws (i think about six or eight, just cannot remember). You will also notice where the main socket plugs into, there are three screws holding that mount. Remove those screws and fold out the plastic. There is a pretty good chance that there is plenty of grime/ dust, just sitting there. Clean this up with your ciurcut board cleaner aswell. while your at it, also spray the plug pack with the circuit board cleaner just to make sure thats clean aswell. Dont worry about the fluid comming out of the spray pack, as its alcohol bassed and evaporates pretty quick. Then put the screws back into place, sockets back into place, and remount the instrument cluster. Finally to make sure that the ground is actually ground, open the hood, and next to the oil filter, you will see a set of wires ground to the engine block. This is your ground for your instrumentation and interior. Loosen the nut holding the wires to the engine block, and spray it with RP4 or WD40, or anything similar (electrical lubricant). This should clean any grime or grease off the mount and should improve contact between the engine block and wires. I tried all this and have found that my speedo has come back to life, working perfectly. It seemed as there was a ground issue and once all contacts have been cleaned, you should have no more problem!! I hope this helps....

Grolla42

Maybe your speedometer cable goin to the tcase and fuel pump went out at the same time if the circuit board is ok afterall