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Trans failsafe prog - wont start

19K views 11 replies 7 participants last post by  cnotes628 
#1 ·
My BMW was idling and trans failsafe prog came on with the battery light. I shut the car off and went to restart but it would not. The battery is brand new. It won't start in neutral and when gears are change it does not light up in the dash anymore. Ideas?
 
#2 ·
Try disconnecting the battery for 20 minutes and see if that resets everything. I know it's a pain, but the least expensive thing to try first. You will have to re-inintialize everything. Instructions can be found on the web. Note that the sunroof initialization, (l learned from the dealer and never found on the web) is completed by pushing in the sunroof button and holding it until the sunroof completely cycles open and closed. Takes a minute or two so don't take you finger off the button.
 
#4 ·
Hmm. Are you certain the battery is fully charged? If you have a voltmeter, check battery voltage with key off, and also while trying to crank the engine. The battery should show more than 12.5 volts if it is fully charged with the key off and if the voltage drops below 9-10 volts while cranking (or while trying to crank), that is a sign of a weak or discharged battery (I know you said it is new) and could cause all of the electrical gremlins that you are experiencing. If not a low battery, then that is pretty much all of the straightforward, no cost diagnostics that I know.
 
#5 ·
I killed the battery on my X5 a few years ago because I left my SAT Radio unit plugged into the cigarette lighter all weekend. It would not accept a charge so I had to replace it. I put the new battery in, did all of the initialization tasks and everything seemed fine. I drove the car back to the parts store to turn in my old battery and when I got back into my car and started it; I got the Trans Failsafe error message. I immediately turned the engine off, waited a minute and restarted it. Everything was back to normal and it has never happened again. My theory was that the old battery was so worn, I noticed the dome lights were much, much brighter with the new battery, that the stored sensor values changed with the new, stronger battery and it tripped a code. Once reset, everything was fine. That's my theory for what it is worth.
 
#10 ·
Hi battery at 12.1 is not really right should be at 12.65 or higher was just watching on you tube and I am an electrical engineer and it was interesting watching
when x5 is turning over it battery level should not drop down below 10v ish is it drops lower then there is a prob

eg from a chart they where showing
batt 100% = 12.65
batt 50 % = 12.25

cant really rem the exact figures but it was interesting watching static battery at 12.1 yes .. its not right first port of call check it out on u tube
and let us know how u get on
 
#8 ·
It's the 3.0. The problem was the range gear selector/neutral safety switch located inside the transmission. Not sure if the two were related but the Ebox fan also needed replacement. It was continuously blowing a fuse and causing all the lights on the dash to come on
 
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