cluster switch - i'm confused (again)

[525i winter driver]

so i switched my cluster with one i pulled out of a junked car. it has the white back and the brown plug.
my old one has a grey back and i can't find any coloured or not coding switch anywhere.

my main reason for doing this tho was to see what kind of a reading i'd get on the fuel level. on my old one, the needle would fall to zero once it reached about 1/4 and the obc would freeze at 18% or so. i have a tank that leaks at 35L or over and i'm trying to decide if i want to change the fuel level sender before i take it to the shop to replace the tank.

last night i parked the car with the needle just recently dead and the obc at around 18%. this morning i started it and got the same result - in my case i think this is usually because the obc isn't getting a signal and is frozen on the last reading it had. i switched the cluster with the 'new' (untested) one and started it. woohoo 70k younger and a dead temp guage. the gas needle went just past 1/2 but the obc was reading 9% what the? for sure i'd be able to spot evidence of an 8L overnight gas leak but there wasn't any. so i went and put 20L in and the needle went to 3/4 and the obc to 45%. i drove around a bit and if you looked it either the needle or the obc by itself it would appear as if they were working normally but they didn't correspond to eachother. if i were to guess how much gas was in the tank i'd guess something pretty close to what the obc says now.

so i want to put the old one back in because it's scary driving around with no temp guage but i'm wondering if i should try changing the capacitors first - can you get those at radio shack or canadian tire or do i have to find an electronics shop or order them? and it would be nice to know i can do a swap later with this other one - i read somewhere the odo on the grey ones crap out at 300k - where is the coding plug on the grey-backed clusters? but i'm edging towards guessing my fuel level sender is bad and the capacitors bad on the 'new' cluster, so i'm wondering if it makes sense to bother. knowing me i'd break something.

[525i winter driver]

ha sorry for rabbitting on a bit there... found good info on an e32 page, http://bmwe32.masscom.net/johan/299960/299960.html i guess i can't switch the coding plug.

i'm going to leave my original as is, change the capacitors on my spare and see how things go from there. fun!

[BMWDriver]

Doesn't the OBC read the fuel in Liters rather than percentage ?

[525i winter driver]

Doesn't the OBC read the fuel in Liters rather than percentage ?

i always wondered that but with the readings i get who knows?

i get a max of around 77.?T:MTL i think it says and a minimum of around 17.?T:MTL. i assumed it was percent, that's what i remember reading.

i put my old cluster back in and it's acting like before except the fuel guage is a little funkier. i think maybe you are right and the capacitors in both clusters are screwy except in my original one it is only the one for the fuel guage and it almost works still. i will know for sure once i fix the spare i think.

no big deal once i get my tank replaced but right now it's a pain cause i can't fill it above 30L and i get no reading under 20L. reminds me of the days way back when i'd put $10 in my 4-banger beater except now i can't go as far!