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BMW E34 5 Series 1989-1995 (525i, 530i, 535i, 540i, M5, touring) Neutral safety switch


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Last Post: May 14, 2013 10:19 PM Last Post By: Danlau
ingemann

Posts: 9
Registered: 02/13/04
Neutral safety switch
Posted: Feb 13, 2006 11:18 AM
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Very suddenly my 540i (auto, ~120,000Mi) started downshifting roughly from 3rd to 2nd and to jerk quite badly when engaging R or D, the latter only intermittently though. Everything had been working smoothly until then, and everything else still does. I have tried to take out the neutral safety switch, but the ignition switch lock lever makes removal of the front mounting screw impossible, and there is no was that lever can come off. It appears to be mounted on a break bolt. I was going to either clean or replace the selector position/neutral safety switch. The Automatic/Manual switch did not work properly either, most likely too much coffee with sugar in it (so why not the same problem with the other switch), but that was easy to clean, and now it works beautifully.
Does anyone know the solution? Fluid level is OK per my garage.
Port Fellamay

Posts: 4,105
Registered: 01/18/04
Re: Neutral safety switch
Posted: Feb 13, 2006 9:50 PM   in response to: ingemann in response to: ingemann
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If your instrument cluster is showing the gears changing correctly, I wouldn't bother with the neutral safety switch. I can't tell you quite what to suspect, I'd have to spend some time studying the system, to check it out. Have someone specializing in BMW check the car out. No one else will have the resources or experience to diagnose it properly.
ingemann

Posts: 9
Registered: 02/13/04
Re: Neutral safety switch
Posted: Feb 14, 2006 8:00 AM   in response to: Port Fellamay in response to: Port Fellamay
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Dear Sir,
Thank you so much for your help. My idea to check the switch comes from other threads telling that a defective switch causes weird problems. The very sudden appearance and the intermittence of the problem also led me to suspect an electrical fault; finally, the Bentley manual tells that a defective switch can cause the jerking. I will very likely follow your advice.
Port Fellamay

Posts: 4,105
Registered: 01/18/04
Re: Neutral safety switch
Posted: Feb 14, 2006 8:45 AM   in response to: ingemann in response to: ingemann
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Curiously I searched if there's some issue with this perticular switch doing that, and I cannot find anything to support that arguement. Though it may be broadly responsible for some trans problems, I don't think the specifics match you problem.

In my opinion your hard shifts are due to sticky valves, and it's taking more high pressure to change the shifts in the valve body properly, making them seem harsh and sudden, because they are somewhat more shot into gear.
525freak

Posts: 41
Registered: 12/20/05
Re: Neutral safety switch
Posted: Feb 20, 2006 5:43 PM   in response to: Port Fellamay in response to: Port Fellamay
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Quick question - if there are sometimes hard shifts, would auto transmission additives help, or do they do more harm than good?

Most of the shifts on my A5S are fine, but sometime quite a yank when reverse is selected (especially when hot).

Thanks.

Paul. :)
Port Fellamay

Posts: 4,105
Registered: 01/18/04
Re: Neutral safety switch
Posted: Feb 20, 2006 7:12 PM   in response to: 525freak in response to: 525freak
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Stuff like the lucas auto trans additive that is for sticky valves does seem to help. However it does change the feel of the transmission as well, and I can't say it's more than a cheap fix to a suddle problem. Probably the best thing to do is to open the pan and spray the valve body down with some electric parts cleaner. Don't use carb cleaner, you don't want a residue that will create more problems.

Changing the fluid then a few times will help the condition. You can try using the lucas sticky valve stuff, and if you don't like the feel of the shifts, just flush it out with all new fluid to get a more normal feel. But opening the pan you have to be very concious of any specs of dirt or whatever getting in, and you'll obviously wanna change the filter as well and make sure the level is perfect.
525freak

Posts: 41
Registered: 12/20/05
Re: Neutral safety switch
Posted: Feb 20, 2006 7:30 PM   in response to: Port Fellamay in response to: Port Fellamay
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Thanks. I might give the additive a try as I can just flush it out.

What do you mean by 'change the feel'? Do you mean the changes will take longer?

Paul. :)
Port Fellamay

Posts: 4,105
Registered: 01/18/04
Re: Neutral safety switch
Posted: Feb 20, 2006 10:21 PM   in response to: 525freak in response to: 525freak
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I'm not sure how to describe it, I just think that the shifts seem heavier, cause it's a heavier oil. It is supposed to build up pressure higher to free sticky valves. It's weird but it does work....
ingemann

Posts: 9
Registered: 02/13/04
Re: Neutral safety switch
Posted: May 11, 2006 9:09 PM   in response to: Port Fellamay in response to: Port Fellamay
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On another discussion forum I found somebody to call. Before I was done telling the symptoms, he told me that the valve body needed rebuilding. A rebuild kit for about $100 arrived in the mail. It took some time to get the tools together (14 and 17 mm hex keys/short sockets, T27 socket, and proper torque wrench (0 - 30Nm)) and find the time, but then it was more messy than difficult; now shifts are very smooth. If anyone is interested, I can give some tips on how to do it. Thanks everyone for offering advice.
Danlau

Posts: 3
Registered: 05/14/13
Re: Neutral safety switch
Posted: May 14, 2013 10:19 PM   in response to: ingemann in response to: ingemann
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I have similar transmission problem with my 1995 BMW 525i. I want to remove the neutral safety switch for cleaning, but there is a lever blocking the screw. Does anybody know how to remove the lever?
Thanks!

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