Fuel gauge not working on E39!

[peaktorque]

Picked up my 535i today . All is good apart from dead fuel gauge . When test drove it orginally I had just assumed that the seller was doing the sellers favourite and running it on vapours. Picked it up today, still no fuel in it....
Or so I thought, filled it up, drove off and fuel gauge still deceased!
In addition to the gauge problem, the 'range' (distance=fuel) doesn't seem to work either (just displays ---). I'm guessing that both share the same tank sensor?
Is it just a case of changing the sensor? I have done a bit of a search on this issue and there seems to be some suggestion that this is a fairly common fault???
Any advice on this would be appreciated!

Thanks

[peaktorque]

Help!

[Fixedwheelnut]

Most common cause is a broken wire on the right hand sensor in the fuel tank, check the resistance at each sensor and see if one is open circuit.

If they are ok then check continuity between the sensor wiring and instrument cluster.

[blackspider]

There are 2 fuel tank sensors on the E39-N/s and O/s.If the fuel gauge fails to rise,even on a full tank then this tends to point to both senders failing(not unheard of).

The senders are accessable by removing the rear seat base,taking out the round panels down to the senders.

If you remove the senders,then using a multi meter you can test the resistance across the 2 terminals to see if it increases or decreases when the float is operated.

There is however an easier way of doing this and thats via the instument cluster test functions.

Test function 6 gives fuel levels either side and overall level.
Test function 2 is a cluster self test-runs all needles,lights through a check.
Test function 21 is a cluster reset.

There is a specific sequence to get to these functions but not for posting.

[peaktorque]

O.k thanks guys! Going to have a look today, so it will probably rain!

[peaktorque]

Gone to town on it! Had a look at connectors on both sides, they seem ok. I have removed the n/s sensor from the tank (the one with a two wire connector) and had a look, no jammed float like I was hoping for! I have manually lifted the float(s?) and the resistance across the two terminals does vary according to position, I guess this means it is working o.k. I haven't tested the other side as it looks more involved. With the ignition on however I did notice that there is only 11v dc supplied to one pin, could the fault be here?

thanks

James.

[peaktorque]

Took the car round to my parents this afternoon. My dad has got hold of a Snap-on MT2500 plug-in diagnostic reader. To be honest neither of us were really clued up on how to use it, but we did manage to get some info. out of it:-

Fuel system 1- (not ready)- open loop
Fuel system 2- - not used

Does this mean anything?

Thanks for any replies

James

[blackspider]

Sounds like tank sender one is knocking the system out.That the one with the fuel pump that you havent taken out(not much harder than the other).

Try pressing the left hand button on the cluster,turn ignition to p1-test 1 will appear in cluster.press the left button til you reach test 21.Take your fingure off the button-wait for it to sayt reset then press-this will reset the cluster and may wake up the senders.

[peaktorque]

blackspider said:

Sounds like tank sender one is knocking the system out.That the one with the fuel pump that you havent taken out(not much harder than the other).

Try pressing the left hand button on the cluster,turn ignition to p1-test 1 will appear in cluster.press the left button til you reach test 21.Take your fingure off the button-wait for it to sayt reset then press-this will reset the cluster and may wake up the senders.

Thanks for your help on this! Just had a go at reseting the cluster as per your instructions. I managed to get "TEST-NR 21" displayed (could only do this by using the r/h button though) once this is diplayed however I cannot get to "RESET", if I use the left button then I can get "LOCK-00" displayed. Am I doing something wrong?

thanks (again)

James

[blackspider]

Sounds like you have the high cluster with the OBC display.
It needs to be unlocked to continue.

YHM

[eliot]

www.ideaphile.com/bmw/540-obc.html

[peaktorque]

eliot said:

www.ideaphile.com/bmw/540-obc.html

Wow! some useful stuff on there! The fuel readings given are diffent to mine (as they would be!) as in the middle value is 0.0! Off-side sender unit I think I need?

Thanks

James

[peaktorque]

Good news!

Removed off-side fuel sender today and found cause of the dead level gauge.
Once the tank access/level unit removed I found a stray wire from the float to the underside of the four pin connector connections.
Repaired the connection and put all back together.... turned ignition on.......
result! Gauge and range now seems to be working as it should!!!

Thanks all for help, espicially "blackspider". Just to carry out a diagnostic check on this fault at an indie. I was quoted £65 an hour!

[blackspider]

No problem...Glad you found the fault