Where is the sword in the E31?

Nice and easy this one....

It is located under the leather knee panel on the RHS of the tunnel....

The panel just pulls off (Velcro ish) You might have to move a small piece of carpet trim as well....

Hope this helps

Alex

Zitat von E31Gill;49115

My fan only blows and minimum or maximum speeds.
I am trying to locate the fan control sword in my car so that I can resolder the joints. I am having trouble locating it. Any ideas?

I have just this afternoon experienced the same problem but mine only blows on maximum. A search of the forums both here and roadfly suggest that the 'sword' is the culprit but I cannot find anything conclusive.

1) Is the sword likely to be the problem?
2) Where precisely is it located, what am I actually looking for and what would I do with it if I find it? Is this within DIY capability

Any help guys would be greatly appreciated, thanks.

Yes, that sounds like Sword failure! Removing the sword on the E31 is very similar to removing it from the E32:

http://www.meeknet.co.uk/E32/Microfilter/Index.htm

There are slight differences as the lower kick-panel is different. The removal of the E31 kick panel is shown in this thread:

http://www.meeknet.co.uk/E31/E31_Brake_Improvement.htm

The output transistors fail, or the solder joints on the transistors fail. The 'full speed' setting activates a relay which by-passes the transistors which is why it will work at full speed only.

Circuit diagram:

http://www.meeknet.co.uk/E32/B…inal_Stage_Unit_Sword.pdf

Thanks Timm, that is excellent information, and I think I will take your advice about a dry (warm) day to tackle the job. If it is a solder problem will it be obvious or would it be advisable to replace the unit?

As an aside, I really miss my old e32, when I chopped it in for the e31 in 1998 I just assumed the e31 would drive the same but in a better looking body. If I am completely honest the e31 has always been a disappointment by comparison. I realise they are different animals but as both were '91 models I can't believe how agricultural the e31 is by comparison. Did you have a similar experience or is your e31 much later?

My pleasure! Here is some more information on the sword repair:

http://www.bmwe34.net/E34main/…ance/Electrical/Sword.htm

As the transistors are so cheap I would be tempted to replace them anyway. The alternative part is available from RS:

http://uk.rs-online.com/web/se…chTerm=486-2206&x=33&y=14

The original BUZ71 is available from Farnell.

I have mixed feelings about the E31 driving experience, after my E32 which was a V8 730i Sport I moved on to E38's and that was a bit of a shock! The E38 drove around like a jelly on wheels (it had the stock 16" wheels on it). But eventually I moved on to my present E38 which has EDC and that goes around corners like it is on rails.

The E31 reminds me of the E32, but is a lot harsher (being a Sport on 18" wheels). However, it handles a lot better, goes faster and is more fun! However, every time I get in the E38 I can tell how far BMW has advanced, the ride is so much better in the E38, it out accelerates the E31, brakes better and everything works more efficiently. It also has so many toys (Nav, TV, EDC, DSC, hydraulic boot, voice control, tyre-pressure control, PDC, massaging seats, Xenon's etc etc) that it is difficult to find a time when the E31 would be more fun!

Zitat von Timm;72566

I have mixed feelings about the E31 driving experience, after my E32 which was a V8 730i Sport I moved on to E38's and that was a bit of a shock! The E38 drove around like a jelly on wheels (it had the stock 16" wheels on it). But eventually I moved on to my present E38 which has EDC and that goes around corners like it is on rails.

The E31 reminds me of the E32, but is a lot harsher (being a Sport on 18" wheels). However, it handles a lot better, goes faster and is more fun! However, every time I get in the E38 I can tell how far BMW has advanced, the ride is so much better in the E38, it out accelerates the E31, brakes better and everything works more efficiently. It also has so many toys (Nav, TV, EDC, DSC, hydraulic boot, voice control, tyre-pressure control, PDC, massaging seats, Xenon's etc etc) that it is difficult to find a time when the E31 would be more fun!

Well... it looks a whole lot better tha any 7 for sure..... If I want gadgets and fun I have the ///M

Zitat von Noggie;72568

Well... it looks a whole lot better tha any 7 for sure..... If I want gadgets and fun I have the ///M

I don't think that was ever in dispute. My apologies if the question of comparison should have been 'off topic'

On a right hand drive car, you also have to remove the steering column as there is not enough room to slide it out.

I can supply these now at £325.00 + VAT. PM me for details. No exchange req.

8Tech.

Zitat von 8Tech;72605

On a right hand drive car, you also have to remove the steering column as there is not enough room to slide it out.

I can supply these now at £325.00 + VAT. PM me for details. No exchange req.

8Tech.

Blimey Gerry, It's not a question of soldering a bad connection then!! I guess that price includes supply, fit, collection, delivery and full valet. (Only joking). Seriously though, is it either this sort of expense or no heater fan

Have a good read of this and make your own decision!

http://www.bimmerboard.com/forums/posts/355700/

Zitat von Timm;72635

Have a good read of this and make your own decision!

http://www.bimmerboard.com/forums/posts/355700/

Good post Timm, are you aware of the success/failure rate for this repair? Looks reasonably straight forward, luckily my HVAC is still functioning fine but I've bookmarked this thread for future reference.
Cheers

Zitat von Timm;72635

Have a good read of this and make your own decision!

http://www.bimmerboard.com/forums/posts/355700/

Thanks again Timm, that is really good. It's a bit of a no brainer isn't it and certainly worth going down this route in the first instance.

It is pretty straight-forward, but you must have a soldering iron with a modicum of power behind it. Trying to de-solder the transistors with anything less than 30W will be a bit frustrating.

I've heard of quite a few successful repairs and only a couple of failures.....

I agree that if you can fix it then this is a good option, however, if the car is off the road whilst you do it, and you spend 4 hours removing and installing it, and it doesnt work, you will be paying £422 + VAT from a dealer for a new one, and another 4 hours work, or waiting a week or two for me to get a new one in.

Having a new one to hand, you can repair the old one and either sell it on or refit it and if it doesnt work, at least you have the car apart already and you can slip the new one in.

8Tech.

That's a good point.......after your repair, just plug the Sword back in without inserting it into the heater unit. It is OK to test for a minute or so without any air-flow past it. That way, if it doesn't work you still only have to do the job once!

Has anyone made any progress with their sword issues? In the process of fitting my "new" Becker, I also replaced my heater controls but my fan control is just as wayward as before so I guess it must be the dreaded sword. Seems like a few of us have the same problem, has anyone done anything about it?

Hiya Nick,

Back in September I got set up to remove the sword following Timm's excellent instructions. You need to be a contortionist to do this job and I failed on that attempt although I will try again. The awkward position you have to work in was more than my poor old body could bear and each 10 seconds of effort was followed by 20minutes of recovery. It would probably be easier if the car was raised to about waist height and you had the stamina of an Olympic athlete.

I have got the replacement mosfets and an electrical engineer willing to do the repair when I eventually get the part out.

One point that my friendly engineer pointed out after reading the repair procedure was the damaging effect of static discharge on these components, no precaution was evident or mentioned in the procedures? Is this correct Timm?

I would be very interested to hear if anyone else has successfully carried out this procedure.

Hi Graham,

Is the difficult bit removing the steering column?

Zitat von Nifty50;84521

Hiya Nick,

Back in September I got set up to remove the sword following Timm's excellent instructions. You need to be a contortionist to do this job and I failed on that attempt although I will try again. The awkward position you have to work in was more than my poor old body could bear and each 10 seconds of effort was followed by 20minutes of recovery. It would probably be easier if the car was raised to about waist height and you had the stamina of an Olympic athlete.

I have got the replacement mosfets and an electrical engineer willing to do the repair when I eventually get the part out.

One point that my friendly engineer pointed out after reading the repair procedure was the damaging effect of static discharge on these components, no precaution was evident or mentioned in the procedures? Is this correct Timm?

I would be very interested to hear if anyone else has successfully carried out this procedure.

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It was a killer of a job to remove the Sword on the E32, and after working on the brake linkage of the E31 (which involved work in the same area) I guess it is just as hard on the E31!



Yes, the FET's are static-sensitive, but are protected once soldered into the Sword. Just keep them in their anti-static bag until needed. Your engineer will know how to handle the devices, but it is not so hard as long as you follow simple rules - work on a surface such as wood, always touch the work before you touch the FET to keep the work and the FET at a similar potential.