Fuel gauge swap

dan_b

dan_b

A2OC Donor
Just wondering, is it possible/easy to swap out the fuel gauge and associated electronics from one instrument cluster and replace it with one from another?
Just say, for example, in a purely hypothetical scenario of course, that you had a 2003 car with a 42l fuel tank, but you had acquired a 2001 DIS cluster for retrofitting. There's a chance that the 2001 cluster won't work correctly with the 42l tank size fuel sender - could you therefore extract the fuel gauge electronics from the 2003 cluster and put them into the 2001 DIS cluster so that everything worked hunky dory?
 
I've never seen a cluster out of a car, so don't know, but could it be that all the dials are part of the same printed circuit board?

Tom
 
they're all one PCB.

"no" is the answer to your question... but to answer the *real* question: well, maybe, because there's no reason why you couldn't leave the old pump and level sender in place and just recalibrate it.

- Bret
 
Hi Dan
I think there are bigger issues than the fuel gauge calibration. The instrument cluster is the hub of the canbus system. There were slight changes to the systerm in 2001 and as the CCU and window control modules in the doors are part of the canbus, I suspect these need to match the cluster.
Out of interest, Sarge posted this 'how to' on the cluster - http://www.a2oc.net/forum/showthrea...ap-front-facia-on-Instrument-Cluster-(Clocks)

Cheers Spike
 
Hi Brett
How do you recalibrate the fuel sender?
Dan

bretti_kivi said:
they're all one PCB.

"no" is the answer to your question... but to answer the *real* question: well, maybe, because there's no reason why you couldn't leave the old pump and level sender in place and just recalibrate it.

- Bret
Click to expand...
 
someone's also misunderstood the way the gauge works. It has a resistance, depending on the level in the tank. Up to the intro of the 42l tank, it was something like resistance goes up as fuel level goes down and then it got switched. So resistance goes down as level goes down. Something like that, it's specced on the German forum and probably in the Wiki (which I also need to fix when I've got rid of this cold).

- Bret
 
The cluster in question is a 980 J part number which I believe implies it's the later iteration - so I'm hopeful it's compatible with my 2003 CANBUS?

spike said:
Hi Dan
I think there are bigger issues than the fuel gauge calibration. The instrument cluster is the hub of the canbus system. There were slight changes to the systerm in 2001 and as the CCU and window control modules in the doors are part of the canbus, I suspect these need to match the cluster.
Out of interest, Sarge posted this 'how to' on the cluster - http://www.a2oc.net/forum/showthrea...ap-front-facia-on-Instrument-Cluster-(Clocks)

Cheers Spike
Click to expand...
 
So really, for the DIS swap, we need to just:

Short out the headlamp monitoring circuit (which pins are these?)
Connect the CAN from the stereo to the DIS for the in-dash stereo info display
Re-calibrate the fuel sender with VAGCOM?
Update the mileage from the old cluster to match the actual car's mileage (I have no interest in clocking) - assume again this can be done with VAGCOM?

Anything else? Any impact on the keys/ immobiliser? CCU?
 
Short out the headlamp monitoring circuit (which pins are these?) --> don't know
Connect the CAN from the stereo to the DIS for the in-dash stereo info display --> don't need to do this, if the radio is on CAN, there are no wires to be pulled
Re-calibrate the fuel sender with VAGCOM? --> if it's a 42l and was a 34, yes, otherwise no change
Update the mileage from the old cluster to match the actual car's mileage (I have no interest in clocking) - assume again this can be done with VAGCOM? --> this is the difficult bit and might not be possible, it's certainly not possible with a standard VAGCOM install

Anything else? Any impact on the keys/ immobiliser? CCU? --> nothing AFAIK.

I can check the DIS replacement threads on the German Forums, but one thing: DO NOT PUT THE IGNITION ON WITH NO CLUSTER CONNECTED!

- Bret
 
Dan
The fuel gauge is integral to the cluster PCB and cannot be transplanted. I looked at this as an option to sort my fuel gauge when I retro fitted DIS to my car, but alas it cannot be done. As far as the sender is concerned, Audi changed the way it operates. I'm not sure which way around (I'll have a look) but gauges read
low resistance = full
high resistance = full
the difference is in how the gauge interprets the resistance value from the sender.
As for calibrating the sender, I have not come across this on VCDS, but it could be possible, again, I'll check.
However, I very much doubt that even if the resistance reading is correct, I cannot see how you could make a 34l winding give a read-out for a 42l and vice versa.
As for mileage correction - it CAN be done but not by Audi.
I had my keys matched to the cluster by Audi, although I understand that that can be done by VCDS to match the keys to the immobiliser.

blue skies
tony
 
it is most definitely possible to align the sender. STG 17 is the Cluster itself, it's group 7. It starts at 128ohms. OK, I have to get the wiki working now. Meh.

There are a couple of 21-42l conversions on the German forum; try starting with teh "SLR" (SuperLongRange) link in #9 above.

- Bret
 
hotstuff said:
As for mileage correction - it CAN be done but not by Audi.
Click to expand...

Wrong! How do you think that Audi replaces a faulty instrument pod? When I had my pod changed on my 1.2 to show MPH, the car was connected to the Audi system and the correct mileage programmed in. It can only be done with a new pod though, after about 50 to 100km it cannot be changed, even by Audi. (Thanks Worthing Audi. My local Audi refused the job!).

RAB
 
As you are already aware, Dan .... if you find all this too much hassle and then discover a cluster which is perfect for your 2003, 42l tank, A2, then I'll have that cluster from you, no problem! Thanks, Dan. OR, you could swap your tank and sender for mine! How about that? LOL!!??
 
RAB, you are correct, mileage can be corrected by Audi, but only when replacing a faulty cluster with a new unit. This proceedure can be done once and only if the cluster displays less than 100 mph. The point the op is asking is how to correct the mileage on a used cluster he has obtained to retrofit DIS. I think my retro fit was the 1st in the UK. I have very good contacts at Audi and a mileage correction (downwards) was not possible. I was able to locate a company here in Milton Keynes that did correct my mileage to within a few miles of the original display. I'll post pics in a few minutes.

blue skies
tony
 
Ok guys, I promised to check and report the way the fuel gauge reads the signals from sender.
There is some interest in this because several members wish to retrofit a DIS cluster to non-DIS vehicles.
According to Elsa vehicles manufactured up to 04/2002 were fitted with the 34 litre tank and the sender worked on the principle of;
LOW resistance (54 ohms) equals 0 litres in tank.
HIGH resistance (209 ohms) equals 34 litres in tank.

From 05/2002 vehicles with the 34 litre tank worked as follows;
HIGH resistance (284 ohms) equals 0 litres in tank.
LOW resistance (66.5 ohms) equals 34 litres in tank.

The 42 litre tank also works;
HIGH (284 ohms) equals 0 litres.
LOW (66.5 ohms) quals 42 litres.

The fuel gauge can be calibrated as Bret suggested.
This is done to get the gauge to accurately indicate the start of the reserve zone and the tank must have 7 litres of fuel in it.
This holds true for the 34 & 42 litre tank.

To have an effective retrofit without the related fuel gauge issues (as I am experiencing), the cluster should be selected according to the fuel sender fitted to the vehicle - simply ensure the build date cut-offs match and of course the tank capacity must be the same.

Trying to fit an early model cluster to a vehicle with a 42 litre tank will cause the most headaches.
Similarly, fitting a late model cluster to an early build vehicle will also create issues.

Hope its easy to understand.

blue skies
tony

blue skies
tony
 
Tony, this is excellent data, thank you.
Do we know how to marry up the Cluster part numbers to the build dates? My cluster has a part number of 8Z0 920 980J, which implies a later build date, but the vendor says it was from a 2001 vehicle?
My fear is that I have the first cluster type, which means headaches!
 
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