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Discussion Starter · #1 ·
Hey Everybody. I'm a newbie to the board and would like to say thanks for all of the valuable information I have gathered in my short time of being a BMW owner.

I have a serious problem with the automatic transmission in my 2000 540 M-Sport. Here's the scenario:
Driving @ 55mph in 5th gear and slowing down for a red light I get down to about 30 MPH and start accelerating but the transmission will not shift any higher than 3rd gear. I tried shifting it manually with no luck. While this is going on I notice smoke in the rear view mirror. Immediately I pull over and see a small puddle of fluid on the ground. I have it towed to BMW and they tell me the pump on the front of the transmission is what is leaking and the transmission is bad. They quoted $7,000. I declined and trailered the car to a local transmission shop that works on BMW's, Jaguar's, Mercedes, etc. This mechanic is telling me that the fluid leak is from a overflow tube at the top of the transmission that was "burping" fluid because of an increase in line pressure. He checked for codes and the only one coming up is the "mass air flow" sensor. I told him about the VW sensor that I learned about on this forum. He is going to put it on on Monday. My question is this: Could the "MAF" cause this? My mechanic also made mention of a speed sensor inside the tranny that could be a possible cause. Another thought after searching through the forum, I have noticed that at idle my interior lights are dim as compared to when I rev it just above idle. It is very noticeable. Could a weak battery or alternator cause any problems of this nature? One last thing, I have been having problems with the car wanting to stall while sitting at stop lights and just sitting in a parking lot with it idling. I would assume that this points to a definate problem with the MAF?? Does anybody have any ideas? Please advise. By the way the car has 150,000 miles on it.

Thanks,
Joe
 

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I have read threads where people got new batteries, and their shifting magically improved. It seems like a long shot, but I can recall at least two different posts stating the same thing. As for the MAF, I know it will cause some issues but I'm not too sure about anything with the tranny.
 

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Discussion Starter · #5 ·
Spinseller -

The first time the mechanic drove it (after adding fluid), it shifted through all of the gears but when downshifting it was still real hard. He checked codes and still nothing but the MFA showed a problem. The second time he drove it he did get it to stop upshifting once it reached 3rd gear but no fluid leakage. I understand he is trying to save me money by trying the cheapest route first (MAF) but I think he is leaning on having to remove and tear down the tranny. I did find it interesting that several people have claimed a weak battery caused the transmission to shift irradically.

Please....anyone have any ideas prior to having to pull the transmission and probably spend a quick $3000......

-Joe
 

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Did you get the TRANS PROG FAILSAFE lamp on your dash? You indicate the symptoms - 3d gear default mode. The 3d gear is the "failsafe" default mode to preclude further damage to the transmission and allows you to "limp" to the dealer (that is assuming something is wrong and that you could do additional damage by driving "normally").

This happened to me and I took it to the dealer. They spent two days troubleshooting it and even called BMWNA but could not diagnose the true cause of the failure. Naturally, they (as all good "stealers" do) recommended replacing the transmission. I opted to take the car without further repair work. In 16K miles and 15 months, the tranny has shifted flawlessly and has had no hint of a problem since. I suspect it was a sensor fault as the day it ocurred, it was cold, wet and rainy. Bottom line, it could be a real problem or it could be a mirage. Double check before spending the big bucks to fix a mirage.

I too have read of some unusual linkages between battery replacement and tranny cures but I suspect these are just coincidences. Then again, never underestimate the cause of an electrical sensor or computer glitch.
 

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. . . I too have read of some unusual linkages between battery replacement and tranny cures but I suspect these are just coincidences. Then again, never underestimate the cause of an electrical sensor or computer glitch.
Maybe the older battery pushes out a lower enough current to cause intermittent failure of marginal electrical connections thus throwing a fault. That was a common enough problem with cars from another manufacturer, (who will remain nameless). The fix was to get a new battery and refresh every every electrical connection, filling each with dielectric grease. That was no fun! :mad:
 

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. . . I too have read of some unusual linkages between battery replacement and tranny cures but I suspect these are just coincidences. Then again, never underestimate the cause of an electrical sensor or computer glitch.
Maybe the older battery pushes out a lower enough current to cause intermittent failure of marginal electrical connections thus throwing a fault. That was a common enough problem with cars from another manufacturer, (who will remain nameless). The fix was to get a new battery and refresh every every electrical connection, filling each with dielectric grease. That was no fun! :mad:

Maybe you could swap a working battery from someone you know . . .
 
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