View Full Version : 1987 635csi Cluster Power

10-27-2016, 04:14 PM
Hello all -
I am in the process of repairing and cleaning my cluster and have run into a few issues. The batteries leaked and were causing a short such that the SI was ON even when the car was off.
So I've removed the cluster, cleaned everything up, removed the clear plastic, wet sanded the interior and repainted (WOW what a difference), installed new speedo gears and now I want to put in new lights. And here are my ??'s.

One of the cluster PCB connectors for an upper light bulb has a damaged trace and I'm wondering if any of you have a photo of this area so I can repair mine.585181
I de-soldered the original battery but now I don't know how to install the new battery, ie where to solder the Positive and Negative leads. I didn't make a note of that prior to removal :(
Next I would like to install the new bulbs in the cluster (some are LED and some are OE) and apply power to test the new bulbs. Does anyone know or have a pin-out for the rear of the cluster? 585182

I have the ETK with wiring diagrams but I can't tell what the wattage and amperage is for the cluster for testing with my ext power supply and I can't figure out which pins on the rear connectors carry current and ground.

I think that's it for now, unless anyone has additional advice.


10-28-2016, 11:29 AM
For #2

The old batteries are held on by tabs that are welded to the battery on one side, and soldered to the board on the other. Remove the solder with a solder-sucker or solder wick (again, see Radio Shack), straighten the pins and remove the batteries. Be sure to remember the polarity of the batteries for when you reinstall them. The original batteries are marked +/-, but the board isn't.You have to rig up a way to solder the new batteries to the board. You can take the old mounting tabs off the old batteries, and remount them to the new ones, but that is tough. You can buy batteries with mounting tabs, the Varta's may come with them, I'm not sure. The Radio Shack tabs won't mount directly to the board, I cut them to fit. You could also rig up a wire to go from the tab to the board. Anyway, take a look at it. It's pretty easy to figure something out.
One warning, on my board the tabs were soldered to the board at one point on one end of each battery, and at two on the other end. It turns out that on the end with two connections, one of them is just for strength and has no electrical properties. I just soldered to the one, but if you aren't sure which is which by looking at the board, You can solder a small wire between the two holes and just mount the battery to one. My batteries originally had a small amount of glue holding them to the board. When I replaced them, I replaced it with some silicone gasket material to help keep the batteries from vibrating loose.
All that sounds complicated, but it's really not if you have a little soldering experience. The only things you have to be careful of are to not crack the board while you are playing with it (not a big deal, it is pretty rugged) and when you solder, don't create any bridges (shorts) between leads on the board. That's easy if you just don't use too much solder. It's probably a good idea to charge up the batteries before you install them if you can.
Then just reverse the steps to reassemble the cluster and reinstall it in the dash. Don't forget to put back in the engine code plug! You will have to reset the service interval indicator after you are done, of course.
Good luck, if you have any questions about it, send me a note.
Use CHARGED NiCads ... some boards will NOT charge up a completely dead NiCd battery, and you'll think you need a new board ..
PS: I found this out when the local dealer was starting to change the batteries v. the board .. they told me my instructions didn't work .. so I came down and found out that *some* SIS bards will NOT work unless the NiCd batts. are charged *before* install And *yes* they will now change the batteries, saving their customers mucho $$$ .. over changing an SIS board

16. Note the solder points for the two batteries, do a drawing of your remote wiring, and have your radio shack battery holder set up. Remove the old batteries (three point support) and remember the polarity. The original batteries were also caulked to the board to reduce stress. Be careful not to touch the CMOS chip, it is very static sensitive. Solder in the new wires and run through a hole you will have to drill in the plastic shell. Go to work with a magnifying glass and check the rest of the solder points on the back of the board, but principally the post connections, they tend to crack the easiest.

17. Reassemble in reverse order, put charged batteries in holder. I located my new battery holder in the glove box recess next to the flashlight, reset the SI board and the OBC and drive down the coast for a well earned glass of wine.

source: http://www.unofficialbmw.com/repair_faqs/sil.html