Start by removing the two #1 phillips screws in the top flange of your instrument cluster. Adjust the steering wheel telescoping all the way out. Put a small flat head screw driver above the plastic flange in between it and the dash and GENTLY pry it down so you can get a finger and thumb between it and the dash to pull it forward and out.

Shove the right end in the gaping hole you just made by pulling the gauges out and you will see some connectors on the back of the cluster. The three large ones are: Blue white and yellow, there is also a smaller blue one in the rear facing up, and a light socket stuck in the back on the rear left side which I beleive is the ABS light. If an auto, there is also a plug for the PRNDL Here's a pic of the back of the cluster for an idea. Remove the b,Y and W connectors by sliding a small flat head screw driver in the black release and GENTLY prying it out till you can grasp it with your finger and thumb and pull it all the way out till it stops. At this point the connector will pull free from the cluster. Remove the white connector and the small blue one. Then swap ends of the cluster that you have pushed into the hole, and remove the Yellow and Big blue connectors and the ABS lamp.


After pulling the cluster clear of the dash go to the dining room table and take these tools, a small flat head screw driver, a #1 longer shaft phillips, and a pair of longer needle nose plyers. Also you will need a soldering iron, and a desoldering tool or solder wick you can get these at a electronics store or bum them from a techie mate like me.

Remove the bottom left corner lamp as seen from the back of the cluster, this will aid in removal of the tacho clock because of the tabs on the tacho. Then remove the 8 phillips head screws which are gold in colour, and have a hex head as well from the back of the cluster. They are only the screws around the outter edge of the cluster, do not reomve an screws from the back of the clocks! See above photo.



Both clocks are held in by pressure and connectors only, so start by pressing on the back of the body of the speedo till it slides out of the holder, after it slides free of the pins on the connector simply slide it up and out like this,



careful not to bend the clock facia tin!

Now onto the tacho, it is a little more of a pain after sliding it from the pins because of this,



after sliding it forward and off the pins, gently tilt it forward like this, then up and out,



After getting both clocks out the cluster looks a tad barren, like so,



Now seperate the green circuit board and the backing which is the pale tan or white plastic thing from each other by sliding them apart, there are two ribbon cables holding the circuit board. Now to the SI board, they look like the next two pics, grab the connectors as shown and pull away from the connector they are plugged into. One is gold and one is white,





White one is plugged into the Si board, goldie is plugged into the tempo and fuel gauge sub cluster.

Now the white backing should look like so:



here is what the three screws look like on the SI board.



one is kind of hidden beside the one ribbon connector. Take all three screws out.

Now gently tilt the SI board as shown here forward, it is only held in by pressure and a couple lame ass tabs, tilt it up from the bottom as shown,



Here are the piles,



notice each has a pair of leads that are + and a single one that is earth, but both are oppisit to each other and if you turn the SI board over to the solder side the connections are the six shiny ones shown here,



Now all that is need is de-soldering the stock dead batteries, and solder in the new! After doing that, simply reverse the procedure and re-install in car. This is the time to replace ALL the lamps in the cluster, and to clean it up as needed whilst apart!

Hope this helps all you blokes! Feel free to PM me if you have any questions before during or after the process. You should not have to reset the SI board after this procedure, but you might. Now all your gauges, OBC and Si lights should work as designed by Bayerische Motoren Werke!


Kev

Thats a good write up mate!
My board is slightly different to that with 2 AA size batteries.
Here is a picture of the back after I had to fix the tracks on the board due to the batteries leaking and corroding it.

There is a new board also that has no batteires, it is $110.00 US and I mihgt buy one for the daily driver...but after replacing the batteries, you can expect at least ten years of operation so no biggie. Yeah mate, I have heard some have two lithium AA batts as well, thanks for pointing that out! Don't know if that is Euro only but we do get Euro cars here in the US as well.

I also have a couple good boards which aren't hashed by leaking batteires if any of you need one I'll send it to ya for price of postage only, but I do live in the US!

Yeah I gathered that by the fuel guage!!
My other one is ok, this one is out of my old one which i am scrapping so i'm ok for now but sure there will be others!

Excellent stuff, Desertfox!! Top marks!!
will be making use of this in the near future and so will many, i should imagine.

I think this should be a Sticky: could a mod. somewhere please do the honours??

Thanks Dave! Hope it helps for some who would normally not want to take it on without seeing it first hand! I jump into this stuff if I have extra parts so next one is a OBC backlight fix. And a writeup on how to reprogram the OBC after a battery fault or fixing the backlight.

OBC back light is just a pair of bulbs in a white carrier - its easy to fix!

Great job there Kev - more inclined to have a go now

Yeah but I'll show how to get the OBC out, and how to not break the board or holder whilst taking it down to the point of you being able to remove and replace the lights.

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excellent, thanks for this!

Is that your engine in your avatar pic? looks kinda interesting!

The types of batteries vary is all i can say. For example, i have seen three types: the original board out of my '87 520i was a one-piece board with no ribbon cables and that had two red aa's.
two other boards i have worked with were also out of 1987 E28's: they were also one-piece items but had the two smaller batteries mounted above either the speedo or the tach, i forget which. These boards were both the same: but one came from a 525e and the other from a 528i.

you base your guide on an earlier type of dash: the most notable difference being 3 red lights on the service indicator instead of one. the dash design was, i assume, revised at some point in the eighties.
I own a complete earlier type of dash and it is fitted with two red aa batteries in the same place as you specified in your guide, DesertFox.
heres a picture of two dashboards, the earlier type is situated above the later type. Speedo's, tacho's, and fromt casings are interchangeable between types but i'm not sure about other components or a complete unit.
any type of batteries (providing they are the correct voltage etc) could, in theory be used, but they may have to be placed in a battery holder and remotely wired in.

Excellent stuff DesertFox...five stars to you sir!

Nope, that is in a CSL Gp3 car, nasty fast that! I think even being normally asperated it was laying down about 500bhp! Here's the car after being sprayed black in gp5 livery.

Dave and all, that Si board is out of a 1985 535i US spec car. I have seen only the board with the two CR series batts like this, and the one which is older I think with two AA's. I have seen but not in person, the one that has no batteries. Nice, I think I'll get one.

That is a lovely car. I almost bought a 72 csi for £5000 was pretty mint too and not far from me.

Wish i had because i've seen them going between £12000 and £25000.
Could have made a few pennies on that one, not mentioning just looking at it for hours and hours!

then you'll love my old CSL. Sold it for big bocks, but wish I still had it.

AIUI the later cluster is simpler, i have a spare cluster from an early M535i auto (new batteries by BMW natch!) which i'm saving and it has much more 'gubbins' that the later ones particulary with how the econometer and rev counter operate.

change must be pre june 86 as this is my build date and i have the later type.

not looked at the batteries though.

Great stuff...

DesertFox - thats CSL is stunning. Any more photos? Put them up in the picture/video section!! I'm sure we'd all love to see more!!!

Unfortunately no, I only have three pics of it and all are from the exterior because the shots of the motor and interior are all missing since I moved. Some day I hope to find them but now I can't seem to locate those or any of a few other things I shot.

That wouldn't be the one by Programa, would it? I've been trying to get hold of the one they used to make for the E24, but no luck so far

It is.

looks like i'll be having a go at this now too - typically after selling my good unit my temp, revs and ecomometer have started flickering - classic SI failure is it not?

Whats the battery spec? and whats to stop be having two AA rechargables remotely? then i can simply solder to the tags?

3.5volts each, so unless you get the very expensive computer memory AAs that are 3.5v each, you might as well get stock replacements or the ultra expensive battery less board at over 150US$

no you're right - just wondered what Sharky had used - 3v 850 mAH though are they not?

I used a single 3.5v AA computer rechargeable for a while but it never worked consistantly so I did that write up after finding stock replacements. All work great now but if I have another problem I think Ill do a bateryless board!

So where do you find the stock replacements then, desertfox?
This weekend I've spent £15 and had to make two 17-mile round cycle rides to the electronics store only to find that my dashboard still wont work properly. Now I know the cause to be that the batteries i bought were only 160mah, this is some consellation as i know what i'm doing wrong. Except its not because I had to modify the tags to get them to fit and therefore cant return them. Ah well, lifes gay pageant, i suppose....
I currently have 2 complete dashes that I am trying to repair so that I can sell: one with AA's and one with the small lithium jobbies.
I have fitted an external 2XAA Battery holder to one of the dashes so they need not be tagged.
However, If anyone knows somewhere that supplies the 3.5v 850mah batteries like desertfox said I would be more than happy, as I intend to offer an exchange system in the near future whereby you send me your old dash, I send you a complete and working one (after exchanging the speedometers and coding plugs so your accuracy of gauges and original mileage remain) the same day and then wire in new batteries in an external holder to your old one, and send that to the next person who sends me theirs.

So to sum up, where can I get batteries, how much do they cost, and who would be interested in an aforementioned exchange system?
Also, are the two varieties of batteries used of the same voltage and amperage?

TIA

I can get them here in US for about 5$ US each, I can pick up a set for you and mail them if I can send batteries across the H2O.....let me know your addy and I can see what it'll cost.