2005 X5 Trans Fail Safe
 

I got a Trans Fail Safe while car was idling in park. Turned ignition off, car would not start. Started acting as battery was dead. Let sit for an hour, car started and drove fine for 3wks. Started car and Trans fail Safe came on again, then put car in gear and pulled off and car was sluggish. Parked car for that day and came back with lights on and would not turn over. Then battery died. Had battery tested and tested good. Recharged battery and install, Trans fail safe again. IDK what to try. Also, 4X4 light is on.

Regards the battery being low it can throw up tons of crazy codes in these cars when it’s low.

Now the battery is charged. With the engine running can you check that the battery is being charged via the alternator at 14.4v (or there about). Check the voltage at the battery posts tho to ensure that the charge is getting to the battery.

Also I’d you haven’t already hook up a OBD2 reader (preferably one that is compatible with BMWs, not just a generic one) and note down all the fault codes.

Wipe the codes completely and then take the car for a test drive and then rescan to see if any of the faults come back.

You may be lucky and the the battery might just have gone below the 12v most of the modules require to no take a dump!

You may have a problem with the alternator. What is the battery voltage while idling? It should be near 14volts.


2002 E53 4.4L
2009 E70 35d

Regards the car being sluggish when the Trans Fail caption illuminated. I believe that the ZF trans clutches for 1/2/3 disengaged and the trans is locked in 4th gear When in D. And still has reverse in R.

So this is a design feature of the box when in Fail Safe. I believe it’s because if the GB were to fail at motorway speeds you definitely would not want it to lock into anything lower than 4th!!!

If you have the older GM gearbox this may indicate something else though.

Yeh when off the battery should be 12.4v or somthing very close.

And with the car running most alternators put out 14.3-14.6v ish


Oops sorry Doug thought you were the OP asking if it should be!

Oh before anyone else asks What’s the the year of the X5, engine type and mileage? All of this can help us help you a bit better.

As there are so many engine types mates to different boxes, LCi/Non LCi..... and so on. it lets the people who are most familiar with your exact set up help you.

change your transmission oil thermatt and cooler i willing to be that helps it it located passenger side bottom raditor front f the car

Last year, my TPF message was because of a failing alternator. 2004 4.4i with only ~40k miles.

I also drained and filled the transmission fluid three times. It was 16 years old, but still looked good. The problem with my harsh shifts was the fluid was low because of a slow leak from the mechatronic sleeve.

Not enough info known. Symptoms align with a starter in failure that pulls too much current pulls the voltage low.


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