E39 540 trans failsafe urgent help please - BMW Forum

eggnchips · 08-23-2011, 10:35 AM

Hi
I have a 98 540i which has been running up until 3 days ago. While pulling away in traffic she suddenly jumped into trans failsafe dumped me in third gear and I had to limp her home. At this point I will say that I had no warning at all, changes had been smooth and performance as normal.
I got her home and disconnected the battery and set about checking and cleaning every electrical contact I could fine boith topside and under the engine and box. This didn't work and I am now trying everywhere to find someone who has had the same problem.

She starts fine, if I put her into revers she shifts straight away as normal. If I put her into drive there is no "creep" she just sits idling. If I increase revs to 1700 she kicks in but trans failsafe comes up right away and she is again into 3rd.

I had codes read byy an indie and he said that I have a stall speed problem in teh gearbox whereby basically the box cannot detect a spped to engag gear. He has advised a new tranny but I still believe it may be electrical.

Does anyone please have any ideas

spankdathass · 09-01-2011, 08:59 PM

Yea it sounds to me like its a possible electrical connection. He didnt give you a code number? We need a number if we can help you in anyway. Also check the connection on the rear end. There is a sensor. Make sure no corrosion has built up, clean and see if that helped. See if you can get a code number. Does it seem to be running rich or possibley lean? Any change in gas milage? Also check for vaccum leaks. Hope i was any help to you.

brettski · 09-02-2011, 06:24 AM

Welcome to the Werkz.

Depending on the mileage and the previosu service routine on the gearbox, it may be that some foreign material (metal, seals etc) has made its way into a place it shouldn't be. I have experienced a few odd behaviour issues with my car, but after having the gearbox oil and filter changed, seemingly unrelated issues disappeared. Go to a reputable specialist transmission shop and get them to service the gearbox, and run diagnostics over it. Make sure that they are equipped to extract the oil from the torque converter. See how things pan out after that. It might cost you ~$200, but it might save you from buying gearbox when you don't need to.

Good luck and let us know how you go.

Jack Dabsy · 09-02-2011, 03:06 PM

Gearbox Oil change would cure it...

eggnchips · 09-05-2011, 11:47 AM

Thanks for the replies. Prior to this she was running fine. I did have an E32 many moons ago which developed a trans failsafe problem and it turned out to be the MAF. I have checked mine though and have my own code reader which is coming back clean.

On the underside I have found two connectors between the engine and the box (sorry don't have a photo), are there any more.

We do have a very good auto trans place in town so I guess that will be my next stop.

Does anyone give any credence to thi sbeing a battery problem ? Before this all started she had been parked at an airport for 15 days and was perfectly fine. When these problems kicked off I did check the battery and it wasn't brilliant but she would always start and there were no other symptoms. Over the weekend however the battery has gone stone dead and nothing had been left on.

I haven't had time to swap it out or do much else but will lok at it over the next day or so.

Thanks again for the replies, much appreciated.

Jack Dabsy · 09-05-2011, 02:09 PM

Hmmm, its a well known fact that BMW's do not like failing currents from poor batteries but this shouldn't affect the gearbox as the alternator would provide most (if not all) of the required voltages for it to re-adapt after any reset due to a dead battery... HTH