I haven't driven the car (an '03 R) for nearly a week, but last night after a short drive I looked down and noticed the fuel gauge was pegged at Full. I knew what was actually in the tank and it wasn't full, but that I had plenty to get where I was going so I didn't stop.

When I reached my destination, I turned the car off and found the gauge remained right where it was with the car on. I waited a few moments and turned the key back on, the gauge advanced a good 60-90 degrees - about the amount of travel it would have needed to get from zero to a proper indication. The additional 60-90 degrees put it WAY past full, the needle almost touching the hub of the temp gauge!

I turned the car off again, and noticed the needle dropped a very small amount. Turning the car on and off in rapid succession - just long enough to get power to the gauge but not long enough to get a reading from the sender - would drop the needle further, each drop just a few degrees. After 20 or so cycles, the needle was resting at 0.

Curiosity piqued, I turned the car to Run and let it sit. Gas gauge popped up to about 5/8 of tank (correct), and then I turned it off. Needle dropped just a tiny amount. Finding the pattern, I left the car...

This morning the same thing. Gauge too high, quick on-off drops the needle, blah blah. In the quiet of my garage I can hear the stepper motor whirring as the gauge moves, but that's the sum total of my knowledge.

A did a LOT of searching, and it seems this guy had my problem too:

https://www.jaguarforums.com/forum/x...e-issue-59824/

It feels to me like the gauge itself and not the sender... anyone else have another opinoin? Another test I can run? Are all X308 gas gauges the same? Can I just plug in a new/used one?

Thanks!

 

Before you replace anything, disconnect the battery for 60 seconds and reconnect it. See if this fixes the problem. It is possible for the gauge pointer stepper motor drive circuit to get in a 'hosed up' state and the battery disconnect will reset it.

 

Thanks - I will give that a try and see what happens!

 

Spent a couple weeks noting symptoms, here is where I am:

A couple days after posting, I ended up driving the car out to the Bay Area. Gas gauge was working normally, after having used the "key trick" earlier in the week to get the gauge back to 0 with the car off.

I left it there with a friend overnight, the next day he drove it back to me but the gas gauge did not work at all - it stayed at zero. I drove the car exclusively for the next couple of the days, and on the fourth restart the gas started working again, and was right for a couple days.

I didn't drive the car at all last week. Wednesday through Friday the battery ground was disconnected.

Yesterday, I started the car and the gauge stayed at zero. On the fourth restart it resumed normal functionality again and remained ok for the rest of the day.

Today, the gauge read too high, just like it was doing a couple weeks ago. What I can say almost conclusively is that I "caused" the gauge to do this. Normally, on every car, I turn the key to run for a second before starting, to give the fuel pump a chance to prime. This morning I did not do that as I was in a hurry and wasn't thinking - I went straight from off to start. When the key first turned, the gauge started to move but when the load reduction for the starter kicked in, it did *not* start to fall... thus, when power returned it just kept climbing...

I think what I have is a stepper motor misbehaving. It's not responding quickly enough to power or lack of power, so it ends up in a position it doesn't expect to be in. I'll also mention the stepper is REALLY loud - loud enough that its antics this morning were called to my attention by the noise it makes!

My plan is to replace the gauge, unless anyone knows of any repair techniques that are appropriate here. In either case, any comments on what's involved in replacing the gauge? Just pull of the trim and remove the cluster, or something more intense? Is it possible to swap just the fuel/temp gauge out of the cluster? Is the odometer data stored in the cluster or the ECU?

Thanks!

 

The odometer data is stored inside the cluster. To replace the entire cluster you would also need a cluster from another 2000-2003 XJR or 2000-2002 XKR....it has different software than the XJ8s which would need to be reflashed to use. If you can find one with close mileage that is probably the easiest, cheapest path. I have heard a Jag dealer needs a special one time software key from Jaguar to change the odometer.

The motor may or may not be the problem. It could also be the ribbon cable to the motor or the electronic controller on the circuit board.

To replace the motor/cable assembly, both front and back covers of the cluster must be removed. Each ribbon cable accross the top must be unplugged. Then the pointer must be pried off (a fork works). Do not break the delicate pointer stops. Lastly the adhesive label with the gauge markings must be partially peeled back (a little heat fron a hairdryer will ease this) to get access to the stepper motor retaining screws. Then you can substitute a stepper motor assembly from a used cluster.

If you practice on a cheap used cluster (if you just replace the motor/cable it can be from a more common 2000-2003 XJ8 or 2000-2002 XK8) you can build some confidence before you open yours up.

 

Thought I'd follow up on this, too!

Since the "too full, doesn't return to zero" problem happened in early October, it has not repeated itself. However, instead I now have "intermittently totally unresponsive fuel gauge." I am not sure if that's an improvement or not.

What's weird about intermittently totally unresponsive fuel gauge is that there *seems* to be a pattern to it. Starting, running, stopping, and restarting the car four time will bring the gauge back to life reliably... but if the car sits for a little while (and I can't define a little while - it's more than a few minutes, less than a few days), the gauge will go back to dead.

Pretty sure it's the gauge... but I am going to wait until the problem gets worse before investigating it.

Also, I've developed a new problem, and that's the left channel on the stereo has stopped working reliably. It'll cut in for a second then cut out. Right side keeps working at all times. I unplugged and reseated the big cable to the amp under the deck, maybe that'll help.

Man, Jags are FUN.

 

It could also be the sender in the fuel tank, but from your original post the misbehavior sounded a bit more like the instrument cluster itself.

 

I had this problem with another vehicle quite sometime ago and it turned out to be a loose ground.
Dave

 

I'm actually planning on investigation grounds tonight, as one thing the amp and the fuel level sender probably have in common is a ground somewhere in the trunk of the car.

 

I have made zero progress on this, but there is some sort of pattern here. After sitting for more than a day the gauge generally won't move off zero. After about three starts - given normal drives between - it behaves itself. Starting and stopping the car is insufficient, there's a time component here. After it works for several restarts - maybe six or ten - the gauge will not reset to zero when stopped. If it sits long enough - more than an hour or two, less than a day, it will return to zero. If you cycle the key quickly, it will reset to zero. If you restart the car before it's reset to zero, it will climb from wherever it is to way past full. Once it's there, it's either letting it sit, or cycling the key or it'll just stay over-pegged. At any time, if you let it sit too long - more than a day - it will reset to zero and then not work for three restarts as above and then the whole thing starts over.

Very weird. But as I only drive it during the summer or in the rare situation I'm hauling people around, I can't quite care about it. I'm sure next summer when it's seeing daily use it will be really annoying.

Until then, I'm just going to add a fuel gauge to casual XJ shopping list, which right now includes a new coolant header tank (still getting an intermittent "low coolant" warning, but no loss (YEAH!)), a new stereo (still sometimes losing the left channel of the radio), and a new steering wheel speaker (I have no chimes). Typical new used car teething problems.

 

Wow, how time flies...


Sad to report the Jag hasn't seen much road time since my last post on the matter, but as it is due this month for its biennial smog test I thought I should get to work on it.


Shortly after my last post the car also developed a P0460 - Fuel Level Circuit A MIL / CEL, which I assumed to be related. Multiple resets, multiple reappearances. The wacky fuel gauge I could ignore, but the light in the dash I could not.


About four months ago I bought a new/used instrument cluster from a Jaguar recycler and popped it in the dash. Despite what has been written elsewhere on this forum and consistent with what WhiteXKR indicated, the mileage information is stored in the cluster... so my 110k XJR currently has 156k. In any case, the new cluster solved the gauge behavior - it now rises and falls with the ignition and fuel level as one would expect.


It did not, however, solve the P0460 problem, so apparently I have TWO issues in play here - a failed cluster and a failed sensor. Kinda weird, right? Fortunately, I had an entire 2003 XJ8 sitting in the driveway (https://www.jaguarforums.com/forum/p...arting-130556/) so I pulled its tank (not so bad, all said and done, but hardly fun) to poke around inside.


I pulled out its fuel sender and it appears to work on a range from about 80ohm (full) to about 300ohm (empty). I provide those numbers with some hesitation as *initially* I got readings of 80-900ohms, but I was unable to repeat those results. Not sure what's going on, but 800ohm of range seems excessive for a fuel level sender, so perhaps my probes were poorly placed or something.


I snagged some harness from the parts car to make my work easier and I've set about measuring my sender (still in the tank) at various fuel levels. Right now, the tank is full and I'm getting 80ohm at multiple checks throughout the day, rocking the car about, etc. I'll check in the future as I use fuel and see where I get. What I believe is that I have a problem with the sender around 5/8ths full. We'll see.


It seems like the used sender I pulled out of the XJ8 parts car should work in the XJR - pn LNG2001AB - although at like $40 I'll probably just buy a new one.


Trivia question: Is anyone aware of another place in the car where a connector similar to the fuel pump/sender connector is used? Since my salvaged test connector is for an XJ8, it does not have the terminals for the R's secondary fuel pump. I'd like to test both of my pumps prior to pulling the tank out to know if I should order replacements. I do not want to pull the tank twice.


Edit: To be clear, I'm not looking for another similar connector, just another place where I can pull terminals and insert them into the connector.

 

Have you got an electrical guide pdf?

Under 'connectors' there's a list of all connectors used on the car, this could assist.

If you're planning on pulling the tank, just buy fresh pumps and be done, you can get the uprated bosch units for less than $80 I think?
I wonder if the sender fault fried the gauge, or the disco ignition cycles

 

New pumps is strong advice, definitely being considered.


I wondered about the sender damaging the gauge as well, but I think it's coincidence. The replacement cluster has a failed temp gauge, same symptoms - sometimes it returns to zero, sometimes it doesn't and "stacks" new readings. After talking to the folks at BBA these types of stepper motor failures are not uncommon. Also, I think there are a *mountain* of electronics between the sender and the gauge - I can't imagine how any errant resistance values would make it to a stepper motor controller. But, who knows?


Do you happen to have a part number for the replacement Bosch pumps handy?