Pelican Technical Article: Replacing Service Indicator Board Batteries on the E30 BMW 3 Series

Did your tach suddenly stop working? Have all your gauges suddenly gone dead for no reason? Are the service indicator lights dead? Chances are that the batteries on the service indicator board have gone dead. This is pretty common problem on the E30 BMW models. In this tech article we will discuss replacing the batteries and get that service indicator working again.

The E30 3 Series as well as other BMW models have a neat little feature that illuminates a row of lights over a certain amount of miles and informs you of when routine service needs to be performed on these cars. Normally, simply running the car re-charges the batteries and keeps the service indicator lights operating. Sometimes, however, the batteries can fail, causing the lights to go dead. It can also cause the tachometer and other gauges to stop working as well. In the case of my car, the lights stopped working as well as my coolant temperature gauge. The tachometer also started jumping erratically and then finally stopped moving.

As the batteries are located in the instrument cluster, it is necessary to remove the cluster. The first step is to remove the steering wheel. Use a flat-head screwdriver to pry out the steering wheel emblem, underneath; you will see a 19mm nut holding the wheel to the steering column. Make a scribe mark or paint mark to align the steering wheel in the right position when you re-install it. Now, remove this nut. Next, rotate the key to the on position, but do not start the car. Turning the key will disengage the steering wheel lock and allow you to remove the wheel. Now pull the steering wheel off.

The next step is to remove the lower panel under the dash, remove the three plastic screws in the front of the panel and the other three screws holding the panel on at the bottom. Now remove the panel. Next, we will need to remove the lower dashboard fascia panel in order to provide clearance to remove the instrument cluster. Reach up under the dash on either side of the fascia piece and feel for a knurled round nut on either end. Loosen and remove these nuts. You can now remove the fascia piece.

Next, look at the bottom of the instrument cluster; you will see four screws holding the mounting frame to the cluster. Remove these. Next look at the top of the cluster. You will see two screws holding the frame into the dash. Remove these as well, and pull the mounting frame free of the car. Use caution as you do this. The frame is very fragile and can break off the upper mounting flanges very easily.

Now, with the frame off, you can now remove the instrument cluster. This may take a little time, as you will have to rotate the cluster around so you can disconnect the various electrical connections in the rear. Take a look at the back and mark each connection. Now disconnect them all. You should be able to remove the cluster from the dash now.

With the cluster out, take a look at the backside. I should take this time to point out that not all gauge clusters look the same, BMW had a few different manufacturers for the clusters, but for the most part they look the same. You should see some Phillips head screws around the perimeter of the cluster. Remove all these, and you should be able to lift the backside of the cluster off.

Look at the center of the cluster. You will see a single Phillips head screw holding this plate on. You must remove this screw to access the S.I. board. Now remove the plate, and grabbing the board by each side, pull it directly out, using care not to break or damage the board.

Now, with the board out, look for the two Ni-Cad batteries, they wont be hard to miss. This is what we are replacing. Be sure to get a hold of two NiCad “AA” batteries that are 3-volts (not the regular ones you find in the store, they might have to be found at a specialty retailer like Radio Shack). You should be able to pick these up at Radio Shack or Frey’s Electronics. Note the service indicator LEDs on top. Simply pull up on the light board and it will pull off.

Next, get your soldering iron out and let it warm up. You will want to use a low-wattage soldering iron to remove the batteries; otherwise you risk frying the board. 10-15 watts should be the max. Also, familiarize yourself with the battery polarity and make sure you understand which way to solder these batteries into the board. Once the soldering iron is ready, unsolder the old batteries. They should pop right out of the connectors when the solder is removed. Before you install the new batteries, make sure they have had time to charge. Now, making sure that the polarity is correct, place the batteries in the connector, and then solder the connections. Keep in mind that we re working around sensitive electrical components, so it’s a good idea to use an anti-static wrist strap.

With the new batteries in place, now is a good time to test the various light bulbs in the cluster and replace any burned out bulbs as needed. I found a couple that needed replacement. Place the LED board back onto the S.I. board. Now, place the board back into the cluster and slowly push it into place, making sure that the pins line up correctly at the bottom. Re-install the access cover and the single Phillips head screw holding it in place.

Next, re-install the rear cover of the cluster and tighten the Phillips head screws. This done, we are now ready to re-install the cluster back into the dash. Reconnect the electrical connections on the back of the cluster, and rotate the cluster so it is oriented facing towards you.

Now, re-install the plastic frame around the instrument cluster and screw it down in place. Once tight, install the two screws through the mounting flanges and up into the dash. Take care when doing this that the cluster is properly aligned. If not, loosen the screws, re-align, and re-tighten.

Now, reinstall the lower dash fascia plate and reaching from under the dash, install the two knurled round knobs. This will pull the fascia plate tight against the cluster.

Now re-install the lower dash panel and tighten the three plastic screws in the front and the three screws in the bottom. With the lower dash panel on, use the scribe or paint mark from earlier and re-install the steering wheel. Once in place and when it is correctly oriented, put the 19mm nut back on and torque it to 50 ft/lbs. Place the steering wheel emblem back in place making sure it is lined up correctly.

Well, there you have it - it's really not too difficult at all. If you would like to see more technical articles like this one, please continue to support Pelican Parts with all your parts needs. If you like what you see here, then please visit our online BMW catalog and help support the collection and creating of new and informative technical articles like this one. Your continued support directly affects the expansion and existence of this site and technical articles like this one. As always, if you have any questions or comments about this helpful article, please drop us a line.

Comments and Suggestions:

Andrew	Comments: Re: Daniel's post. Have you figured it out yet? I am having the same issue as you. Someone suggested it was the ignition sensor switch wire, but I have yet to figure that out. Let me know if you find anything. Thanks
April 19, 2012

icibuy

Comments: Part 3 Last Lithium Battery info

The newer style SI board uses a MnhO2 Lithium battery by Sanyo CR1425OSE.
The board on my 1987 325is is dated 13.94, and numbered 992 647 196.
It clearly is a replacement, likely installed after only seven years.
The batteries on my board are dated 93-08, and measure 3.17V in 2004.
Nominal end-of-life voltage is 2.0V, but at 2.5V little capacity remains.
The two 3V cells are connected in parallel but isolated by diodes.
Either cell can fail individually and the board will still work.
The cells have an extra isolation film under the conformal coating,
presumably to protect the board from overheating or leakage.

More details about the battery:
Sanyo CR14250SE 3V 850mAh 14.5x25mm 1/2 AA size lithium cell.
The 14250 is a standard primary non-rechargeable Lithium type, available
from multiple sources.
sanyo.wslogic.com/pdf/pdfs/CR14250SE.pdf
The 'SE' variant was optimized for high capacity and long shelf life.
Other variants are optimized for high discharge rate or light weight.
The standard 'SE' discharge rate is 0.5 mA.
This is ten times less than the power needed to light a small LED.
At the standard rate the cells will discharge in 72 days.
At a 10uA rate the cells will last 10 years.
The temp range is -40C to +85C, rather than -20C+60C of other brands.
The cell may weigh up to 11g, rather than as little as 7g.
The Sanyo 'SET-FT' suffix indicates welded tabs for board mounting.
Modern cells are available in 950mAh versions, but long shelf life and
seal life are more important than capacity.

April 10, 2012

icibuy

Comments: Part 2 The Lithium battery board fixed the design problem. It has two
non-rechargeable 3V lithium cells that are diode isolated from each other
and main battery power. Either cell can provide back-up power, with the
load normally shared to provide twice the life. Even if both cells
fail, the main battery can still power the circuitry.

So now that you know how the SI board batteries work and fail, how do we
fix the problem? I'll start with the NiCad board, since people with bad
lithium batteries might not even know that they have have dead batteries.

There are several web pages with excellent instructions and pictures on
removing the SI board. I won't repeat them here, instead only covering
the battery information that isn't obvious from physical disassembly.

The original NiCad batteries are standard size AA cells Varta 500 RST
with board-mount tabs welded on the ends. Your options are to buy
replacements with the same board-tab connections from a specialty
battery supplier hobby shop or on-line, buy cells with solder tabs or
wires attached, or use wire a remote battery holder to the circuit
board.

Whatever mounting option you choose, use *only* standard capacity,
high-temp NiCad cells. "Better" battery chemistry types NiM-H,
Lithium or specialized cells rapid charge, high capacity cells are
not better for this application. Non-NiCad chemistries will have
different voltages, and high capacity or rapid recharge NiCad cells have
design compromises that reduce longevity. NiM-H batteries are reported to
work, but the continuous trickle charging will destroy them.

A good choice of battery is the Sanyo high-temp standard capacity cells.

If you can't find cells with solder tabs or want to remote-mount the
cells for easier replacement, put them in a holder. Radio Shack has a
nice dual AA cell battery holder, part #270-408. It's fully enclosed
with wire leads already attached, and typically stocked in-store for
about $1.49.

I don't recommend Radio Shack as a NiCad battery source. They will do
in a pinch, but the cells are overpriced and not the best type for this
application.

Now on to the lithium battery SI board. This is much more academic,
since these board generally don't have problems. However our cars are
getting old, so some of these boards may start needing battery
replacements at some point.

April 10, 2012

icibuy

Comments: Found this written in 2008-seems to be a lot of great information-although I have no way at the moment to validate any of it:

Part 1-The Service Indicator SI board is a circuit board in the instrument
cluster. Its most obvious function is to monitor the engine usage in
order to count down the time until the next recommended oil change or
inspection, reporting using the bar graph on the cluster. A more subtle
function is to read the "code plug" at start up and use this information
to translate fuel injector and ignition pulses to drive the tachometer
and fuel economy meter.

The SI board batteries provide back-up power to retain the service
counter when the main battery is dead or missing. Much like a UPS for
a desktop computer, they are intended to prevent data loss during a
brief power outage rather than to be a long-term power source. Since SI
board batteries are a pain to replace, you should not remove the battery
for storage and avoid leaving the car sit with a dead battery.

There are two major variations of the Service Indicator SI board in
the instrument cluster, the original type with NiCad batteries and the
redesigned retrofit board with long-life Lithium batteries.

NiCad boards have two 1.2V 'AA' cells in series. Fresh batteries will
power the SI board for about a month if the main battery is
disconnected, and will slowly recharge when main battery voltage is
restored. The NiCads typically to last for 5 to 15 years.

Lithium boards have two 3V lithium cells in parallel, which will last for
well over a decade of stand-by use. They should power the SI board for
several months if you remove the main battery, but this will permanently
consume part of their life.

The problem with NiCad board, and the reason for the SI board redesign,
is that NiCad cells don't fail gracefully. If you discharge an old cell
to zero volts really below 0.6V, metal whiskers start growing
internally. These will short out the cell, preventing it from
recharging at all. The original SI board had two design flaws based on
connecting the microprocessor directly to the batteries: it would
discharge the batteries completely trying to preserve the counter state,
and shorted batteries will prevent the microprocessor from working at
all when the power is restored. Even if you don't care about the oil
change suggestion, other functions that depends on the coding plug
e.g. the tach will not work.

April 10, 2012

Daniel

Comments: Good day smart Bmw people! My 1993 318i beemer instrument panel is allo of a sudden nt working, onley speedo and the red batt light is working...with that my fan for fresh air also stoped working!! When i turn the key to start, in that 2seconds that the car is being started in the fan works and also the service lights and also idle needle but as soon as the car is started everything dies again! Fan, petrol guage, ref needle, car temp guage.. Batt light stays on until i ref the car a bit... I also fitted a nother instrument panel to check wheter myne was broken but with that one also nothing worked... No fuses are blown or nothing... PLEASE ANY HELP?? MANY THANX

March 31, 2012

Joe

Comments: I have been trying to get my Tach up and running. I have replaced the old with a new. Check the fuses 10, 21. I did find there are two wires that are not attached to the center green circuit. One is blue with yellow stripe and the other a white wire that comes from the on board computer module above the radio. Can you talk me through where these wires go. My assumption I know, I know is that this should rectify the non working Tach. Other suggestions welcome on a fix. Thanks, Joe

March 30, 2012

cunaco	Comments: Hello: I have a BMW 735i, 1988. It uses E32 cluster board. I was told a battery drain of about 300 mA was because of a fault in this board. I changed the electrolytic caps, and now I don't have the bat. drain, BUT NOW NO GAGE WORKS, all dead ie. speed, fuel, etc. Any suggestions? Thanks
March 12, 2012

DonnyCPT RSA	Comments: i have a 320I beauti 1991 model my service lights are all burning they plugged in the service light cancel thingy but it didnt work they say my batteries are flat could it be? why are they all burning?? anyone know what i can do?
March 12, 2012

Spider123!	Comments: I have a 87 bemmer E30 325is and I have checked all my cluster lights and I have change out the batteries for the cluster but my cluster lights don't work and my tach and gas gage does not work. Is there a picture of the back of a 87 beemer 325is E30 cluster with the location of everything. Help Please?
March 8, 2012

skalei	Comments: Hi Wayne Does the 92 325 i have nicad Batteries for the gauge. Cluster?
December 20, 2011

ozzfan101	Comments: ok so heres a dumb questions how many batteries are there? and also on my 1987 325i the speedometer and odometer and fuel gauge do not work but my rpms and temp gauge works could it be that its one battery and not the other? or could it be a fuse
December 14, 2011

edmund	Comments: Hi all have 1986 325e have si board is out, it’s in mint conditions like new, has no batteries never solder in and no ic integrated circuit board no 62110152532 any advice? Thanks john.
November 22, 2011

marsgorski	Comments: Regarding the batteries, is EACH battery supposed to be 3V so 6V total? Or are the two batteries together supposed to put out 3V? I went to Batteries plus and they only had 1.2V NiCd rechargeable batteries in the AA form. Thanks
November 12, 2011

ed	Comments: how do i reset the thing?
November 9, 2011

demonchild	Comments: You do not have to pull the steering wheel. I just finished this job on and 85 BMW 325e, and the cluster comes out without any problems.
August 2, 2011

demonchild	Comments: A couple of pictures would have saved a thousand words and made the whole thing a lot clearer. As they say, it was clear as mud, but it covered the ground.
August 1, 2011

advwilly

Comments: I read an article that I should connect 3 wires from the SI board NiCd battery connector to the battery case. one for the +, one for the -, and the 3rd one between the 2 batteries. The articles says that the batteries not only supply 3V or 2.8V to the major components, it also supply 1.5 volts to other parts of the cluster.
Is this true? Could this be the cause of the erratic tachometer?
Appreciate your reply

July 7, 2011

advwilly

Comments: I followed sharpp and installed a battery pack with a long wire to make replacing batteries easy. After installing it, the temp gauge and tachometer seems to work fine. After a while, the temp gauge and the tachometer seems eratic. could this be caused by the long wire? Also, the speedometer and the odometer stopped working too. Are all these related? Where can I get a circuit diagram for the instrument cluster?

July 6, 2011

Mike	Comments: OK, read all this and your blowing my mind with this 3volt stuff... a batt. cell is rated 1.2 volt granted a fresh single cell batt may test near 1.5 volts.. My question is do I try to replace with two units rated at 2.4 or 3.6 volts any one have the answer?? I still have not found a AA size batt rated at 3volt?? Help!!
July 1, 2011

Dave	Comments: How do you recondition 1994 E34 service indicator board. I can't see any batteries.
May 31, 2011

Dean	Comments: hello, I have an 1989 325i AT, and am having a guage problem. The car was sitting for some time, and I was having trouble getting it to turn over. Pulled both sending units and bench tested. Check voltage on wires, eventually giving up and taking it to a shop. My problem now is the fuel guage either stays on empty or breifly moves to 3 quarter tank. usually reads empty though. Any insight you could provide would be greatly appreciated.
May 22, 2011

jeff	Comments: I have a big orange sticker with an aarow pointing so some kind socket with german wrighting on it on the bourd with the batteries was wondering that it was pointing to or says
May 8, 2011

MTpalm	Comments: Could bad batteries lead to a fuel gauge that goes all the way full regardless of the actual level in tank?
April 12, 2011
	Followup from the Pelican Staff: I don't think so. More likely your fuel sender level is stuck in the tank. You might want to take it out and replace it, or by simply removing it and reinstalling it, you may loosen it up a bit. Also, make sure the connection is tight and complete. - Wayne at Pelican Parts

buddymybuddy	Comments: what would cause the airbag ligh to suddenly come and not go off on my 1996 328i bmw convertable? thanks.
September 7, 2010
	Followup from the Pelican Staff: You need to pull the codes. Perhaps it's the belt buckle or the seat sensor, those tend to go out quite a bit. See the article on code reading here: http://www.pelicanparts.com/bmw/techarticles/Mult-Air_Bag_Lamp/Mult-Air_Bag_Lamp.htm - Wayne at Pelican Parts

buddymybuddy	Comments: where are the brake and clutch switches located on a 1990 325i bmw? thanks.
September 7, 2010
	Followup from the Pelican Staff: These are located right near the pedals. Here's an article about the brake switch: http://www.pelicanparts.com/bmw/techarticles/E36-Brake_Switch/E36-Brake_Switch.htm - Wayne at Pelican Parts

buddymybuddy	Comments: will bad cluster batteries cause the cruise control to suddenly stop working on a 1990 325i?
September 6, 2010
	Followup from the Pelican Staff: Perhaps, but I don't think so. I would take a look at the brake pedal and clutch pedal switches, as these often wear out and can cause the cruise control to stop working as well. - Wayne at Pelican Parts

Brandon

Comments: Great write up. This helped immensely. Though, if anyone out there has their SI board out of their car, can you please measure the width of the battery contacts and post those two measurements here? There are two wide contacts and two narrow contacts. What are those measurements? Looking for SI board measurements from a 1991 318is to be more specific- which requires two 1/2 AA 3v Sanyo batteries if anyone was wondering.

August 9, 2010

jj	Comments: i swinish my bored and every thing works except my tack and theirs this weird wire cit behind the cluster
August 9, 2010
	Followup from the Pelican Staff: That doesn't look normal, I would reconnect it. - Wayne at Pelican Parts

Sharpp	Comments: I just replaced my batteries on my SI Board. I took one step up and wired in a batery pack with a wire long enough to fit up under dash. Next time I have a problem I do not have to remove Ins. panel. I had spare hole where there was no ins. lamp, I used this hole to rough the battery cables out to the back of dash. I have a 1987 325e and did not have to remove anything on steering column.
July 9, 2010
	Followup from the Pelican Staff: Clever idea, thanks for sharing it! - Wayne at Pelican Parts

btbiii	Comments: Don't waste your time with first message, there are actually 2 blue wires with the yellow strip that appear to go into this green receptacle. Any idea which goes where?
June 20, 2010

btbiii	Comments: Houston WE HAVE A PROBLEM-1988 325IX. ON backside of cluster-There is a small black connector-Blue Wire yellow stripe that goes into a Green receptacle. Unfortunately there are 3 sections to the receptacle it could plug into a inner, a center and an outer. Do you know which one it belongs in? I thought they were all gendered-STUPID ME-Thanks
June 20, 2010

btbiii	Comments: Thank you for outlining basic process. In my 325IX I had to remove the upper steering column cover to allow enough space to remove dashboard facia. This was the most time consuming part as the ignition switch makes it difficult to remove cover. There is also a WHITE electical connector at face side of cluster that must be pulled out prior to pulling S.I. board. Unfortunately my board is covered in battery acid from a leak and is probably history. Thanks again Pelican for your technical support.
June 6, 2010
	Followup from the Pelican Staff: No sweat! - Wayne at Pelican Parts

Minnesota

Comments: I have read elsewhere that a cause for the Service Indicator Light to stay on regardless of attempts to reset it with the reset tool may be that these batteries are dead. Everything on my instrument panel works properly, but my oil inspection light stays on despite my attempts to reset it. Or it goes off for one start/run cycle, only to come on again the next time I start the car. The other odd thing about the oil light is that it only comes on once the car has been warmed up. It never comes on in the morning after the car has sat all night. Should I tear into the dash to replace these batteries or is there something else going on here?

March 9, 2010

vschlueter	Comments: Just clarifying the Battery issue - so any 3v 2000mAh AA size should work - Ni-Cad or Ni-MH or Lithium ? let us know since the article specifics say Ni-Cad...thanks for the data ...
February 2, 2010

aurelius	Comments: How does one go about charging these specialty batteries prior to installation?
February 1, 2010

perry131313	Comments: no im running standard ignition.iv changed the batterys rev counter still not working!!!
August 24, 2009
	Followup from the Pelican Staff: I would suggest taking it then to an odometer shop, and they can put it on the bench and test it there. - Wayne at Pelican Parts

ivantcho	Comments: In regard to the battery type, BMW factory inserts TWO types ;. See what wrote "JP 91iS" at 09-07-2008, 09:54 PM - http://www.m42club.com/forums/archive/index.php/t-222.html
August 23, 2009
	Followup from the Pelican Staff: I would indeed recommend checking to see what's in there first prior to purchasing replacements. - Wayne at Pelican Parts

BMW-North	Comments: In regard to the battery type, they are 3V batteries and not AA as stated in the article. Often the instrument cluster in E30 and other BMW models stopps working or is erratic when a solder line is craked or broken. Reflowing the solder can fix this. Refer to other articles elsewhere Ie. fanatic boards etc on reflowing the instrument cluster circuit board
August 10, 2009

mistagregory	Comments: I've just taken my whole instrument cluster out and the batteries I see are not "AA". They're Sanyo 3v batteries. So after reading the article I went out and bought pricey AA NiCads and took this whole thing apart only to find the article is incorrect. Am I supposed to be looking for other batteries somewhere else?
August 8, 2009
	Followup from the Pelican Staff: Sorry about the lack of clarity here in the article. I believe that AA refers to the form factor of the battery, not the voltage. So, yes you can have 3V AA batteries. I will have the article amended to make that very clear. - Wayne at Pelican Parts

perry131313	Comments: iv tried this to no aval.i checked the 3 wires that plug into yhe back of the tach.and iv got 2 wires live and 1 ground earth but no pulsing when i rev.any ideas thanks
July 17, 2009
	Followup from the Pelican Staff: Do you have an aftermarket ignition like MSD? Those often cause problems and require a tach adapter. - Wayne at Pelican Parts

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Pelican Technical Article:

Replacing Service Indicator Board Batteries on the E30 BMW 3 SeriesJared Fenton

Replacing Service Indicator Board Batteries on the E30 BMW 3 Series
Jared Fenton