Fuel gauge not working

[kamold]

There is a useful post on the Ross Tech forum which explains the differences between short to plus, short to ground faults etc:

Testing - Open Circuits, Short to Ground or Positive, etc.... | Ross-Tech Forums

[Old Navman]

There is a useful post on the Ross Tech forum which explains the differences between short to plus, short to ground faults etc:

Testing - Open Circuits, Short to Ground or Positive, etc.... | Ross-Tech Forums

Thanks - it'll be tonight's reading

[Old Navman]

There is a useful post on the Ross Tech forum which explains the differences between short to plus, short to ground faults etc:

Testing - Open Circuits, Short to Ground or Positive, etc.... | Ross-Tech Forums

Today I've tried troubleshooting this

1 - checking the plug (as below - ignition on) resulted in 0.9V between the connector 2-3 blue purple/white wire and 0V on brown/blue stripe earth? wire.
2 - Testing for Short to Ground (as per Ross Tech) produced battery voltage 0.9V
3 - Testing for Short to Positive (as per Ross Tech) showed 12V.

There does not seem to be a specific fuse to cover fuel gauge that I could find? but is there any way to power up and check the gauge itself?

[Old Navman]

An update (sort of) - I've had one of the TTY guys have a look at this for me. Despite swapping Fuel Pump Controller (from R36 I think it was), both fuel sender units he was unable to pinpoint where the fault is. In any case the fuel sender units (in the car) were testing a moving resistance and the fuel gauge itself needle could be moved using the VCDS so unlikely indicating a mechanical fault to the gauge itself.

[MMR36]

Hi,

Maybe a longshot...

I had a fuel supply issue a couple of years back with a low fuel pressure sensor fault. Long story short, once the sensor was replaced and couple of other bits, all the hardware was good, save for the gauge measuring. Turned out the coding for the gauge was corrupted. The tank characteristic curve for the left tank (from memory) was missing and the gauge 'code' could only see one tank. Therefore, fuel load was incorrectly calculated (not helpfully, above what was in the tanks) so just over half full on the gauge was empty tanks.

Perhaps check the tank characteristic curves in the coding for your dash. (I note mine is a later dash than yours)

Cheers

An update (sort of) - I've had one of the TTY guys have a look at this for me. Despite swapping Fuel Pump Controller (from R36 I think it was), both fuel sender units he was unable to pinpoint where the fault is. In any case the fuel sender units (in the car) were testing a moving resistance and the fuel gauge itself needle could be moved using the VCDS so unlikely indicating a mechanical fault to the gauge itself.

[MIG]

I am guessing you have the older red screen cluster?

With the correct plug-and-play adaptor, I think you can just drop in a B7 cluster.

If you don't mind coming down this way, I have a spare B7 cluster and the tool to correct the ODO

[kamold]

Yes you can install a UDS cluster. You'll lose the comfort and lighting menus, but they can be controlled indirectly with VCDS.
Need a 32 to 36 pin adapter and the front trim piece which is a different shape.

[Old Navman]

Hi,

Maybe a longshot...

I had a fuel supply issue a couple of years back with a low fuel pressure sensor fault. Long story short, once the sensor was replaced and couple of other bits, all the hardware was good, save for the gauge measuring. Turned out the coding for the gauge was corrupted. The tank characteristic curve for the left tank (from memory) was missing and the gauge 'code' could only see one tank. Therefore, fuel load was incorrectly calculated (not helpfully, above what was in the tanks) so just over half full on the gauge was empty tanks.

Perhaps check the tank characteristic curves in the coding for your dash. (I note mine is a later dash than yours)

Cheers

I had not tinkered with this coding at all unless it got corrupted 'by itself' but I will try to have a look at those details next time I've got VCDS hooked up.

[Old Navman]

I am guessing you have the older red screen cluster?

With the correct plug-and-play adaptor, I think you can just drop in a B7 cluster.

If you don't mind coming down this way, I have a spare B7 cluster and the tool to correct the ODO

Correct, the reddish display. Thanks for your offer, I might just take you up on that one of these days. Incidentally, I was at Mordi about 2 weeks ago could have popped in for a chinwag. How do I contact you - can you PM me your mobile number? Cheers

[Old Navman]

Yes you can install a UDS cluster. You'll lose the comfort and lighting menus, but they can be controlled indirectly with VCDS. Need a 32 to 36 pin adapter and the front trim piece which is a different shape.

I gather this will work with my existing Canbus modules, etc. Not that I have UDS clusters laying around but I might just have to get one if at the end of the day I can't get this working. I guess I'm being mindful of how much I have to spend versus how much the car is currently worth which is not a lot. It's been suggested that I simply carry a jery can in the boot.