battery light and transmission failsafe program on 2000 BMW 740i

My battery light came on while driving. Soon after the transmission failsafe program came on. Once i got home, i turned off the car and have had to charge the battery just to start the car again... battery is still on. Could this be the alternator or perhaps some faulty wiring between the battery and the alternator...

by in Charlotte, NC on July 19, 2009
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3 answers 3 comments
ANSWER by , July 19, 2009
It is most likely the Alternator. Usually the brushes wear down until they will not carry any electrical current on a Bosch Alternator. I would have a shop do a charging system check just to be sure though. It is not a cheap Alternator to buy and not very easy to install. The wiring goes bad pretty rarely and the fact that the light is on means that there is most of the needed circuit continuity in place. I would never put in an after market Alternator in these cars. I used to work for Bosch. BMW, Mercedes etc need high quality parts. it is how they are engineered. Often you can just replace the brush pack on a Bosch Alternator. ($20) This is what have done many times. I have seen them go for 350,000 miles and more. have a sharp BMW tech fully inspect your charging system,. it can be a good German car independent shop, including a full systems scan and complete Charging System Voltage Drops and Battery ( both of them ) load tests and specific gravity measurements. Then you can repair your 740i once and repair it right. These cars are not cheap to keep on the road. I hope you realize this. Best of Luck! Good Luck!
COMMENT by , July 19, 2009
thanks dan.. I dont think i have a bosch alternator in the car, I believe it's an aftermarket alt. This is the 2nd time in 2 months that this has happened. What could be killing the alt?
COMMENT by , September 16, 2010
it it the alternator and cost about 700 hundred dollars installed by bmw shop, the alternator itself cost between 300 and 400 hundred dollars , the labor is not a easy task, so ad at least 3 hrs labor
ANSWER by , July 20, 2009
Hi, Yes,Dann is right. But it could be both things the alternator or the wiring. If you need help with your car come visit us or call us for a consultation. We specialize in european cars and have all necessary diagnostic tools for these cars. You can read more about us at . We use only high quality parts and never sell the customer that he doesn't need for his repairs. Very reasonable prices.
ANSWER by , September 15, 2010
right now my 745 is on the way to the bmw shop for repairs, mine had all this symptoms plus a bit of smoke and funky smell in the fire wall in the engine compartment, smells like electrical.
COMMENT by , January 31, 2011
my car is doing the same thing. What caused this??