My girlfriend has a 98 xj with the 4.0 with aw4. 158k miles on the clock. From the beginning, the gas gauge has not been displaying properly. When the tank is full, it would function normally, until it get to between 1/4 to 3/8 full, then it would drop down beyond E and get the light to turn on. Sometimes she would have to turn off and turn it back on and it would function normally.

Her dad bought new fuel pump and sending unit brand new and installed it, and we both saw the old sending unit, it was really bad. We thought it solved the problem.

The gauge still has not improved. It still display that the tank is empty but we know there's still some gas left. I m wondering if there's problems with the gauge cluster or a connection somewhere?

Is there a computer that controls the gauge cluster somewhere? I want to be able to check the ground connections on that module. U know how Cruiser54 always say RCBRC.
I noticed that there's a computer module mounted right behind the emergency brake lever on the center console. Do that have anything to do with the gauge cluster?

Any input would be greatly appreciated.

 

You could always pull the gauge cluser and check the connections to it. See if there is any corrosion or anything going on.

 

I plan to do so. I wanted to see where else I can check connections, so I can do it all at once, instead of going back here to see what someone else says then go back and check it out and forth.

I plan to check the ground on the fuel level sending unit, too, but I'm stumped to what else I should check.

 

I think that the light will come on when there is 3 gallons or so left. Is that what you mean? Since the replacement, has the other problem gone away? It was very common for 97 and above sending units to fail...my '98 is doing the exact same thing. After a half tank, it jumps to E and back all the time. I never really know how much gas I have, lol

 

No. It would come on when there's like 8 gallons left. It's not being truthful about exact amount left over.
Since the new unit was installed, exact same problem still remains. That led me to believe there's poor ground connection somewhere.

 

That could very well be. I've read something about bad grounds on the fuel pump assembly before, but I can't quite recall from memory. I do remember someone saying that they added their own ground from the assembly to the unibody.

 

Hmm if it all comes down to that, then that's what I ll have to do. I just need help on locating all other possible connections. Any computer modules that control the gauge cluster, etc.

 

I don't know of any modules that control the cluster specifically, but it might be worth it to pull your cluster and check/clean all of the electrical contacts before dropping the tank. Good luck!

 

Do u know what exactly that module under the center console is for?

 

I think its either for the airbags or seatbelts

 

I've read that it could be for the air bag, but the seat belt detection wire runs into there too. I tried searching for that one and haven't found anything about it. I guess I never really paid much attention to it when I've had my console out! lol

 

The reason why I asked is because the emergency brake lever broke on my 99 xj and I removed everything so I can take out the lever, and I decided to drive to work so I can repair it there. While I started up the jeep and after driving 30 feet I noticed my gauges wasn't working and it said NO BUS on it, I figured it was the module so I put it back on the metal floor so it ll have ground signal, and the gauge cluster started working again.

I don't think that computer module is to be blamed for my girlfriend's 98 though, because ONLY the gas gauge is not working properly. Maybe one of the wires though. I ll definitely check the connections behind the cluster tomorrow.

 

Hi Guys , I'm new to the forum and to the XJ ( 1996 ) had it for about 6 months now, had the same problem with the gauge going mad when about 1/4 full, I had a spare pump assembly so just swapped out the sender unit and all good, if you do pull the unit watch out for the pesky rubber locating cone, when I pulled the assembly it left the cone in the bottom of the tank which means getting your hand in there to retrieve it as I found it all but impossible to get correct alignment when refitting the unit into the tank without having the cone located on the unit before insertion. Didn't have to drop the tank to do the above, unit located on the uper forward face of the tank.

 

'97 and above models have the fuel pump module directly on top of the gas tank, so it has to be dropped to access it. I will probably drop mine to see if I ca n fix the the sending unit before splurging on a whole new assembly (as nice as that would be).

 

So I just checked all connections on gauge cluster. It seem ok. I even took off the lens in front and checked the needle for any resistance or if there's anything out of ordinary. It seem fine.
I removed the center console to look at the computer. All is well.

So I guess my next step is to pull back the carpet and check the wiring because I noticed that the wiring for fuel pump comes out of the tank and goes up in the floor in a rubber grommet. I think maybe one of the wiring is perhaps squeezed too much somewhere under the carpeting.