Help, e53 problems
 

Hello everyone I'm new here. I have had my 4.8is for about 6 months now. I'm having some kind of electrical issues. During driving, my dsc light will come
On, abs, brake light. The navigation will flash on and off. The car will then studder. I'll turn it off and let it sit for 10-15 min. And it will clear codes and be good. I went in the interface were I can view voltage. With car off it's right at 12v. With it running it's all over the place. From as low as 12v to a spike as high as 15v but it's steady at 13.8-13.9 bouncing occasionally to 14.0. Is this the voltage regulator causing this havoc? Also the trans safe mode will kick in. Any ideas? I figure battery/alternator but the alternator is working fine. Now I'm guessing alternator voltage regulator. Any help is greatly appreciated. Thanks Eric.

this is alternator (70% chance) and/or battery (remaining 30% chance). the faulty alternator (regulator within) can kill an otherwise good battery. electrical fluctuations will create a serious havoc on the car's modules, especially the spikes... 16V is deadly for most modules... you are at 15V, so the modules survive but not for long... it might be easier to replace the whole alternator as opposed to just the voltage regulator...

do a search on the forum, there is wealth of info on this subject...

Definitely replace the alt. as mentioned above. I bought on on eBay for about $200 or less. Its pretty easy to swap too. I think it took me an hour.
BMWs are finicky about power so don't put it off. In fact with the spikes you are seeing Id park it until you swap it. It's just one of those things thats best not to gamble with.

Yep alternator, same exact problem mine even spiked to 17 volts may have been 19 once. trans fail safe and everything. i would just do the alternator, the regulator can be tricky

Alternator or battery. I replace atl and it fixed the issue. GET THIS FIX ASAP. It took me some time to diagnose this issue where I ended up driving it and it pixelate my navigation screen all over. fix it asap or dont drive the car.

How much coolant do you lose doing this replacement and what kind of replacement coolant did you use?

Anyone have a link to a how to? I have the new alternator and belt

Here is a How To from Bimmerboard - same engine (if you have a V8) How to Replace Alternator in a 99, 00, 01 740il

Id get 3 gallons of antifreeze. Its not a bad job, a bit tight to get it out, and it's pretty heavy - just take your time. I used a piece of cardboard to keep up with the bolts that hold the alternator in, as they are different lengths. Just rough sketch the pattern and push the bolts through, cant go wrong.

There may be a DIY on here, but I haven't looked. Try the search feature - Good Luck! (wear gloves to save knuckles)

:iagree: I would eliminate the battery first by getting a load test done. Local auto parts stores will do the test free.