OBC mystery

[tim eh?]

Since my dash is apart I decided to do a fix I've wanted to do for a while - the OBC. Mine works fine it's just the LCD is flaking away.

I picked one up a while ago at a scrapyard. I had looked up the part # on realoem and it matched. When I switched it though, not everything worked. The obc wasn't receiving vehicle speed so all the consumption etc. was blank. Everything else worked ie the code function, temperature, date, etc.

So today I decided to switch the LCDs. Here's some pics.

http://www.bimmernut.com/forum/attachment.php?attachmentid=6749&stc=1&d=1241563622 http://www.bimmernut.com/forum/attachment.php?attachmentid=6750&stc=1&d=1241563622

http://www.bimmernut.com/forum/attachment.php?attachmentid=6751&stc=1&d=1241563622 http://www.bimmernut.com/forum/attachment.php?attachmentid=6752&stc=1&d=1241563622

When I put it in though it looked more like e.t. phoning home, it was all messed up.
I was worried I had busted something but I put the old LCD back in and it works fine like before.

While I was switching back I noticed the part#s on the obcs don't match.

mine -65811389619
scrapyard's -65818351055

the scrapyard obc matches what realoem says I should have, but it doesn't work properly in my car.
a search for the part# on my obc gives "part not found".

any thoughts?

[shogun]

Do you have a high version cluster or low version = with or without check control. If without check control, your OBC needs a chip. Does it have a plug for the coding plug or not? http://www.gunnar525.de/screwings/bc4_umbau_codierstecker.pdf
Not needed in E32, but both OBC are used on E34 and E32,

[Tron5]

The OBC with part no. 65811389619 expired from manufacture in december 1989.
And your other OBC with part no. 65818351055 expired from manufacture in juli 1997.
There are several other part no. for OBC´s, each for different years, the latest(and most likely the last one BMW will produce) has part no.65811384149

[tim eh?]

Do you have a high version cluster or low version = with or without check control. If without check control, your OBC needs a chip. Does it have a plug for the coding plug or not? http://www.gunnar525.de/screwings/bc4_umbau_codierstecker.pdf
Not needed in E32, but both OBC are used on E34 and E32,

I have the stupid grey back cluster that stops at 300,000km with the coding plug in the wiring plug... I think that is a high version. I have swapped it with a white one from a 525i and it works except for the gas and temp guages which I think are busted. There is no plug on my obc, here is the back of it. I tried to follow that link but the german is beyond me. Looks like the guy made his own coding plug(?). out of his old obc?

Thanks for that info Tron. What surprises me is that the LCD swap didn't work. :(

This isn't a major concern of course, just a minor disappointment. But maybe if I find an obc with the same part#... Anyway, now I know it's a pita I'll wait another 15000km and then deal with it when I have to swap clusters I guess.