Trans Fail Safe HELP X5 2005 4.8is
 

hello , I own a 2005 X5 4.8is 81k... Engine valve seals rebuilt and battery replaced in Nov 14... was driving Sunday and went up a fairly steep street , all of a sudden the car switches to Trans Fail Safe mode...I park the car , come back later and it turned on and drove fine.... Took the car for an oil change and explained the Trans Fail safe to the mechanic... when he has the car up on the lift , we noticed some leakage on the Transmission pan... I had them change the transmission pan seal and filter and add 5 liters of that " lifetime " fluid....the car drove fine , then went up another incline and it went into Trans FaiL Safe mode again... Shut car down , called mechanic , drove the car home ( not in Fail safe mode , but the car felt sluggish ) Today I was taking the car to the mechanic in Queens , I live in Manhattan...as i was on the approach to the midtown tunnel , one car away from entering , all the lights in the car start flashing and I cut the ignition... The car wont restart , so I use the Battery booster to jump the car and pull it over to wait for the tow truck... The car gets towed to the mechanic , and he starts the car ... starts fine... checks the alternator and it gives off 14.8 volts... he says that is perfect voltage..

The mechanic is going to check the Battery and run further diagnostics... He wants to check the starter and Alternator by inspection ( start charging me money to find them and inspect the wires ) Other then the recent Trans Fail Safe mode the car runs great... I don't think its the transmission as the car shifts fine... when I was there for the oil change , the mechanic did say it was giving off some codes related to voltage but " nothing to worry about "

I am not really super knowledgeable about cars , but love this forum and it has helped me with other car issues and to become better educated about my X5... ANY help or advice would be great...

THANKS

I suggest starting with having the battery load tested and to unlock the cluster and monitor real time voltage. 14.8v is high. BMWs are very sensitive to low or excess voltage with the result being all kinds of weird things can happen. In addition, when fluid is added to the transmission it should be filled to the point a small stream runs out and then with the engine running run through the gears, then drive it enough to bring the fluid temperature to operating and then check it again and top it off as needed. All done with vehicle level.

Thanks , I will have that checked ...and also suggest the unlock..

Update... The voltage from the alternator is actually 14.34...close to the recommended 14.4 volts... BUT the alternator is giving a fault code during the diagnostics... Thoughts??

New alternator??

Thanks

It's still a maybe that the alternator is bad. I would unlock the cluster and drive it and watch for spikes or a sudden drop in voltage which will most likely be an indication the voltage regulator is bad rather than the alternator.

Check your yaw rate sensor under the centre console.

Could be loose or faulty.

Pics by QSilver7
http://bimmerboard.com/members/q/ori...r%20Sensor.jpg

The trans failure message just mean a fault code has been encountered and the transmission is going to limp mode. The best thing would have been to bring it to a BMW specialist that has the equipment to read the EGS module and any other modules in the car.

The fact that both of these occurences happened when you were going up a hill would suggest a fault in the fluid pressure or a difference in various speed sensors used to monitor the trans performance. The trans might have been slipping when going up the hill and the various speed sensor informed the computer that the slippage has exceeded the acceptable range.

There is a seal within the valve body that has been known to fail. When you had the pan off that would have been the time to replace this seal. Do a search on this forum for your ZF trans and the valve body seal.

http://www.xoutpost.com/1035383-post12.html

My bet is alternator too.

Many thanks !!!

A low voltage can cause the trans fail safe message, I would start with the alternator as others have suggested.