BATTERY OR ALTERNATOR QUESTION

[sandecki]

My wife just called me, she was driving the car and got a battery light on, few miles later all the lights came on, the message display shutoff and she pulled over, seems like the car died. She has mentioned a Transm Failure Light...Is it a Battery or Alternator considering the car died like this during driving? Thank You for your help,

B

[primetime]

Alternator...probably...The car won't usually just shut off while your driving if its just the battery. But I'm not 100 percent sure..

[Bimmer Ese]

My money is on the alternator. My 330 did the same thing.....battery light came on, then the radio started cutting in and out. Made it home, hooked up a meter to the car (read 8.8VDC), turned the car off, and never came back on until I replaced the alternator.

What size engine do you have?

[sandecki]

it is 2002 x5 4.4i

[sandecki]

also..I am not sure if it makes a difference...battery has never been replaced at 110k miles and 6 years

[Bimmer Ese]

If you are able to start the car (or jump start it) and if you have a digital mutlimeter, measure the voltage to the X5. If it's below 12 VDC, then the alternator (or voltage regulator) is toast.

I think the V8 alternator is liquid cooled.

Dan

[MPDano]

Originally Posted by Bimmer Ese

If you are able to start the car (or jump start it) and if you have a digital mutlimeter, measure the voltage to the X5. If it's below 12 VDC, then the alternator (or voltage regulator) is toast.

I think the V8 alternator is liquid cooled.

Dan

What voltage should it read while car is idling?

[B5M4W0]

13.8 to 14.8v at the battery if the alternator is charging properly. Sounds like the alternator died and it ran off the battery until it died.

[MPDano]

Yup, dropped my altternator off yesterday to get rebuilt. Mine was reading 11.8 while idle and 12.1 with car off.

[Bimmer Ese]

Good luck with the rebuild. Keep us informed.

Daniel