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3-Series (E21, E30) Chat relating to the BMW 3-Series from 1975-1983 and 1984-1991 line. Specific models: BMW 315, BMW 316, BMW 318, BMW 318i, BMW 320/4, BMW 320i, BMW 320/6, BMW 323i, BMW 320i. E30 Family models include: BMW 325e, BMW 325i, BMW 325is, BMW 325ix. is the premier BMW Forum on the internet. Registered Users do not see the above ads.
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Old 06-30-2004, 09:31 PM   #1 (permalink)
Join Date: Jun 2004
Posts: 6
shaman97 is an unknown quantity at this point
Just removed the SI board from a recently purchased '89. The batteries I've seen in illustrations all look like typical AA batteries you'd put into your flashlight, remote control, etc. Not these...they are about half as long, made by Sanyo, with a name of 'laser' n them. The two batteries are held together with what appears to be epoxy. Also, there's a fluorescent orange sticker on the board reminding me to put a three post jumper in the lower (ON) position.
Anyone know the vintage of these boards? I don't want to replace the batteries if not needed.
Oh, the brass nut beneath the fuel gauge was missing. Could this be the cause of the gauge 'jumping' when in the 3/4 full position? Also 'jumps' if I press lightly on the plastic cluster case. Will replace, anyway.
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Old 07-02-2004, 11:34 AM   #2 (permalink)
Join Date: Jul 2004
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7hills is an unknown quantity at this point
I would try replacing the nut first. This problem is most often caused by a bad ground (jumps when you push the plastic).

If the batteries are dead they can be ordered at your local Radio Shack or other electronics store. You will need to look at the old batteries to see how many pin connections go through the SI Board to be sure to get the correct replacement. They can have one or two pins in different arrangements.

There is another option to bypass the SI board and solve several different problems. It has been posted on another forum at on the e30 forum. Here is the basic info.

The crossover or jumper is with the SI board completely out, Not just the lights. If you are looking at the sockets where the SI board plugs into the instument cluster then all you need to do is jump the two sockets marked X. This will send the temp signal on to the temp gauge rather than thru the board. All other signals are intact and all lights will work except for the brake lining wear indicator.
Be sure to put the hood on the check light back in even though the SI board will be removed. Otherwise, when the check light comes on it will also illuminate the places where the SI lights used to be.

It's very simple and even a paper clip would probaly work.


-------- -x--x-- SI ByePass

Good luck!
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Old 07-03-2004, 03:13 PM   #3 (permalink)
Join Date: Jun 2004
Posts: 6
shaman97 is an unknown quantity at this point
Thanks for the info 7hills.

Looks like the battery in my SI board is a lithium (non-rechargeable) battery. Shorted pin 7 to pin 1 on the service connector, but the indicator lights didn't reset, so it looks like I need new batteries.
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Old 07-05-2004, 09:45 PM   #4 (permalink)
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Starmavin is a jewel in the roughStarmavin is a jewel in the roughStarmavin is a jewel in the roughStarmavin is a jewel in the rough
Your batteries are like mine in my 89, they are stubby 3V batteries found at radio shack, they are made for cameras. Kinda pricey though. If you find a cheaper replacement let me know. A jumping fuel gauge is about 90% the sending unit. So I'd advise checking your sending units out put with a multimeter.

Good luck
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