XSeries-forum

Happened yesterday when driving down a big long hill gathering speed so i obviously had to brake,gearbox dtops down a gear holding you back,and thats when trans fail safe came on the dash again.turned ignition off for a couple of minutes and all well again.happened twice now both times on that hill.

You need to get the codes read, if your gearbox has been performing ok up to this point and has no previous bad history then it's probably a wheel sensor or the ABS module
When the fault occurs do you loose the speedo

First off disconnect the battery then charge it with something like a CTEK charger conditioner. if the battery is over six years old then replace it. It may simply be a battery issue. if there is the slightest weakness in the battery in these cars it can cause all sorts of issues

Second, try this reset -https://www.youtube.com/watch?v=r6mVEXhCY4o

Third, read this - talks about speed mismatch and the problem arising when driving up/doown hills which is what you mention in your postshttps://xoutpost.com/bmw-sav-forums/x5-e53-forum/90257-trans-failsafe-program-may-never-occur-again.html

Post back and let us know how it goes.

Smee

Ok cheers.will have a read now.

You MUST plug in and read the codes transfail safe can be anything and can be totally unrelated to the gearbox

Yeah just a found a post with someone who had a 740 and was coasting down a hill with throttle closed which meant no airflow and turned out to be airflow sensor.any way i have a diagnostic laptop on order so will find out next week. ::)