Instrument cluster failure for everything except speedo and tachometer

[Coyote_ar]

Hi everyone, so my instrument cluster (Gen1) was working great after changing the 5 usual capacitors.

Suddenly during winter it started failing to start when starting the car, only speedo and tachometer work the rest (display, temp, fuel, mileage) is dead. Backlight does work for everything except check panel which is off.
Then after a while it would come back online (it reverted to the fatherland initially with language in german, then it switched to the usual spanish).

Lately, it has stopped starting up completely. Not only that, after having the car without battery for a few days, the OBC went into PPPP state. I googled and i says that this may happen when the OBC fails to communicate with the instrument cluster.

I tried disassembling it, all caps look good. i dont see any indication of humidity, or any defective component.

Any ideas what may be causing this? Regards

[shogun]

check the board for bad/cold soldering points, I once had that on my E32 750 with a grey backplate cluster (first generation), my wrenching buddy, which is an electronic engineer, checked it and found bad soldering points on the pins of the connectors, here some pics when we did that long time ago http://www.bimmerboard.com/forums/posts/569942/
t found with the wayback machine an old instruction, here the link, download it. Refers to instrument cluster before redesign 01/1989. http://web.archive.org/web/20040704130421/http://www.bimmernut.com/~billr/images/earlycluster.jpg

[Coyote_ar]

ok, that makes sense. i will check that.

i will need a new soldering iron, the one i got has a hard time melting that solder.

[Rustam]

I had this problem once. I removed all conectors from the back, and with a needle, forced the contacts one by one towards the center of hole in which each of them was mounted. This allowed the contacs come to hold each pin of the incoming connector better, and the speedometer worked normally again.

[Coyote_ar]

i will try that first, it seems to be easier than resoldering those contacts. plus i did fiddle with this instrument cluster quite a lot, its possible some pin is not making contact.

[Rustam]

i will try that first, it seems to be easier than resoldering those contacts. plus i did fiddle with this instrument cluster quite a lot, its possible some pin is not making contact.

The instruments are also contacted by sort of pinching clips, isn't that right? May consider doing the same on them. ALSO there is a type of compound that aides electrical contacts at retaining connections. I am not sure, I think Jeff "Regal" knows the name, and shared it once.

[Coyote_ar]

yes, basically just check that all plugs/pins are good. i will tear it appart during the weekend and see if i can get it sorted. will come back with an update later on :)

[Rustam]

Yeah, I think the speedometer and the tach have thicker pins and engage with their contacts better, unlike the smaller dials. Getting back with the update is a great idea. Good luck!

[632 Regal]

Check the solder points and all electrical contacts going to the cluster.

As Rustam mentioned the contact cleaner is called Stabilant 22. It is VERY expensive these days. I still have some left that I bought from a member here a million years ago. Works very good in a dropper bottle.

For most of the electronics that I work on I use Deoxit D5 in a spray can which is a cleaner and lubricant. Used mainly in component repair such as slides, dials and switches. It is expensive but in my case it has paid for itself many times over on the first use.

[Rustam]

Jeff is the man.