Trans Failsafe Prog -- Now dead Battery -- What is going on?

[morganlopez]

Day 1: I started my 2001 540i in the morning Trans fail safe error came on along with other dash lights. I drove it about 3 miles (using only 3 gear apparently). I parked the car for an hour. It started fine and drove fine but the battery light was now on. I drove it 3-4miles and parked it.

Day two: I drove the car 5 miles to the store. The battery light was on, the car ran fine. At the end of my trip the radio signal got weak, the interior lights got din and the windows closed slowly.

Day 3: Car will not not start. Interior lights come on but it will not turn over.

Does anybody have an idea of what is going on? I am thinking my alternator or battery are having problems. Should I be worried about the transmission?

What should I expect when I take it to a mechanic.

Any input would help. Thank you very much.

[marti5]

New battery by the sounds of it would be a good start, as its probably the original which would make it approx 8+yrs old......

[MADDOUG]

Would not be worried about transmission.

Low system voltage ie duff battery always causes weird problems like this.

When you drove the car after parked for an hour the trans prog was gone because the battery had charged.

Anything can cause trans prog to flash up not just gearbox problems,ie an engine sensor will cause ecu to flash it up,its the ecu's way of protecting the car from being driven with a fault that could damage it.

So the ecu see's low system voltage or it just does not have enough power to compute properly so shuts car down to limp mode to protect it.

[AlpineSixAndSeven]

aMy 740 came up with a transfail safe error right before the Batterey died i think a new battery would solve it

[morganlopez]

Thank you all for the advice. Thank you, Thank you.

I had the battery tested today and it is fine. After it was charged I reinstalled it in the car and it started right up. The red battery light is still on and not all electronics are working properly (radio). I disconnected the battery while the car was running, it died instantly. Is this sounding like any alternator problem. Could it be something else?

Thank you so very much for helping me with this.

[marti5]

That does sound like your alt is shot....

[e34lvr23]

i'm not sure if the newer 540i's have the fuseable link but i'd check that also!