Trans fail safe again

[Zedhed]

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.

[henrym3]

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

[Smeeagain]

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

[Zedhed]

Ok cheers.will have a read now.

[strummer]

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

[Zedhed]

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. ::)