Replaced the alternator - now what?

[djazzmo]

My 2002 Q45 was exhibiting all the signs of a weak alternator. TCS and VDC shut off at about 5 miles of driving. The driver side headlight was begining to flicker. I had the system test and it said that the alternator was not charging up to 13 volts. I replaced the alternator with a rebuilt unit (could not afford a OEM at this time) but all of the symptoms continue. What else could it be?

[F50Qship]

Did you take it to the dealership for system test? Have they test the battery for charging?
If these tests have been performed then the ECU needs to be reset.

I still have the original starter, ballast, alternator in my F50 at 90K miles. I don't how long it will last since I've read failed starter, alternator, ballast especially in 2002 Q45 as young as 50K miles.

[sergey85]

naw i dont think you would need to reset ecu for an alternator, it would have been reset anyways since u unplugged the battery, but test the battery aswell and check all your connections over again. make sure they are tight and no corrosion build up.

[F50Qship]

It's the battery charging test not alternator that ECU need to be reset.

[djazzmo]

Isn't the ECU reset from disconnecting the battery? It took me a couple of days to finish the work and the battery was disconnected the whole time. Is there another way to reset the ECU?

After completeing the job I had the battery put on a charger since it was only at about 75% charge but that has not helped.

[sergey85]

^u got it, unplugging the battery should reset it but no need to reset ecu when doing an alternator, its not needed. never heard of resetting ecu for alternators usually its done when doing a engine or performance mod or engine repair type stuff

[F50Qship]

I had the same problem with my 02Q two years ago when my battery is not charging to its full capacity. I had the battery replaced and reset the ECU. Resetting the ECU is done by plugging the OBD to the data link connector. The dealership performed this test and reset my ECU and checked for stored error codes. Have the dealership performed full electrical diagnostic test.

I bought a laptop consult to performed full test for my 94Q. I had my ABS and airbag light came on recently. I just plugged my laptop USB to the data link connector and run tests. So far no error codes but light still on. Full out my FSM and finally found how to reset my airbag and abs.

I'm pretty sure you can download FSM for your 02Q. Our 02Q has more electronics (I believe 3-5 separate 64-bit processors) and more complex to diagnose.

Good luck!

I bought a laptop consult