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7 Series - E65 / E66 (2002 - 2008)
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  #1  
Old 02-07-2011, 01:35 PM
josephbphillips josephbphillips is offline
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Exclamation Power Issues, battery drain, christmas lights- 2004 745li

I have read through the other threads I could find on issues that sound similar, but I am not sure it is a match to those issues. I am going to be long winded rather than risk leaving something important out. I appreciate the help!

Over the last year or so, I had issues with random messages coming up at times that didn't make sense. For example, I had a high temp warning come on a couple times immediately after starting the car when it had been parked for hours. Simply turning the car off and back on cleared the warnings.

I had the dealer check that out but the codes didn't seem to stick in the system and they didn't have any suggestions.

This continued extremely sporadically until the last few months. I began to have issues with all sorts of lights coming on, including parking break warnings, transmission warnings, and more. Usually, simply restarting the car would clear the errors.

Until one time the car wouldn't start back up. I had the battery replaced at an indy shop, and they seemed to know what they were talking about with regards to the software and systems. They insist that the battery was correctly registered in the system.

The car was much better with the new battery, but it would still throw the same errors if I stomped on the accelerator. Over the course of the last month, the errors became more common, including several times on the freeway in the middle of a long drive. This time, in addition to the parking and transmission errors, the radio would fade out of certain speakers, then shut off, then come back on like normal.

Today, the car threw up the errors after a cold start. I shut it down to restart it, and it wouldn't restart.

It is back at the indy, and they recharged the battery. They said the alternator appears to be working properly, and that the battery appears to be fine. They mentioned a small power drain, of about 1/4 amp, but were not sure of the cause.

If the battery and the alternator are OK, am I down to the power module? Any ideas on the power drain? Would these symptoms make sense if the battery was not registered properly?

I am looking to get rid of the car soon, so I don't want to sink a lot of money in to it.

Help!
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  #2  
Old 02-07-2011, 02:50 PM
745Japan 745Japan is offline
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Replace your Alternator, it's bad.
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  #3  
Old 02-07-2011, 03:02 PM
jbhoot jbhoot is offline
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What distance do you drive everyday? If it is a short distance then the battery doesn't get enough time to charge. These cars consume a lot of current when they are running - while your alternator and battery may be fine - it just may not be charging enough.
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  #4  
Old 02-07-2011, 03:50 PM
josephbphillips josephbphillips is offline
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Thanks for the replies!

I picked the car up this afternoon. The shop charged the battery, but that is it for now. It still has issues with killing the electronics when I mash the gas.


745Japan- I asked the shop specifically about the alternator, as I had read that usually the battery and alternator tend to die together. The shop insists that it is in good shape. Is there something I should have them do to check in a different way?


jbhoot- I make some shorter trips around town, but my commute is 1.5+ hours each way at least two days a week.


I appreciate the suggestions!
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  #5  
Old 02-07-2011, 10:33 PM
745Japan 745Japan is offline
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You can get one of these and monitor output charge, Alternator should give you 14v or just a tad less. If your only getting 12v or anything over 14v then its faulty. Not sure where you went for service, but BMW told me the exact same thing ( alternator is ok, doing great, blah blah blah). These guys rely on the computers dang near 100% of the time, so if the software says it's good then it must be right. WRONG!!!!. Same thing happened to me last month, my car was in and out the dealer for couple weeks. Had it not been for Keif and others ,who knows. I replaced the alternator with a new one, AYE it works, no more Christmas lights. We fixed it!!!. Yeah ok, wanted to smack the rep because it was me who read all these threads, bought the alternator from the USA and did my own research.

Just venting, sorry bro. Here ya go, which should allow you to monitor voltages while the car is in motion. A multimeter works however, the alternator maybe performing fine but intermittently.

http://www.amazon.com/gp/product/B00...pf_rd_i=507846

Last edited by 745Japan; 02-07-2011 at 10:34 PM.
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  #6  
Old 02-08-2011, 11:13 AM
josephbphillips josephbphillips is offline
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Thanks 745Japan. It seems like it would make sense that the shop only tested the alternator in the garage. And since the issues have only been occurring while driving, that could be the culprit.

While I wait for the tester to arrive, two questions:

How would I know if it was the power module instead? Do these symptoms sound like they could be from not registering the battery?
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  #7  
Old 02-09-2011, 09:33 AM
josephbphillips josephbphillips is offline
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I was able to access the "secret menu" this morning and take the car for a short drive. Upon starting the car, it is showing about 10.5v- obviously super low. In driving it, something wierd happens. The voltage slowly dropped down until it was close to 7v, causing all sorts of alarms along the way. Then, it shoots back up to close to 14. This pattern happened again, but this time only dipping to 9v. After that it floated between 10-14v.

I just want to confirm that this sounds like an alternator issue and not a power module.

Thanks!
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  #8  
Old 08-07-2011, 08:45 PM
dd1509 dd1509 is offline
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What is this "secret menu"? And how does one get into it. Directions please.

Thx DD


Quote:
Originally Posted by josephbphillips View Post
I was able to access the "secret menu" this morning and take the car for a short drive. Upon starting the car, it is showing about 10.5v- obviously super low. In driving it, something wierd happens. The voltage slowly dropped down until it was close to 7v, causing all sorts of alarms along the way. Then, it shoots back up to close to 14. This pattern happened again, but this time only dipping to 9v. After that it floated between 10-14v.

I just want to confirm that this sounds like an alternator issue and not a power module.

Thanks!
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  #9  
Old 08-07-2011, 10:34 PM
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csmeance csmeance is offline
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Quote:
Originally Posted by josephbphillips View Post
I was able to access the "secret menu" this morning and take the car for a short drive. Upon starting the car, it is showing about 10.5v- obviously super low. In driving it, something wierd happens. The voltage slowly dropped down until it was close to 7v, causing all sorts of alarms along the way. Then, it shoots back up to close to 14. This pattern happened again, but this time only dipping to 9v. After that it floated between 10-14v.

I just want to confirm that this sounds like an alternator issue and not a power module.

Thanks!
It's def. the alternator. Get a new one put in and everything should be good!

Quote:
Originally Posted by dd1509 View Post
What is this "secret menu"? And how does one get into it. Directions please.

Thx DD
search for "unlocking" and "gauge cluster" and "secret menu" and you'll find it.
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  #10  
Old 02-12-2012, 11:34 AM
7owner 7owner is offline
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I recently replaced my alternator in my 03' 745li and I am getting 12.5 volts at idle and 13.9 - 14.1 volts at driving speed. Is this normal or would you think the rebuilt alternator is not good?
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  #11  
Old 02-12-2012, 11:40 AM
Khabar Khabar is offline
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alternator

I have old battery is about 6 years old. I get 11 amp with ignition on and 14.9 at idle
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  #12  
Old 02-12-2012, 12:36 PM
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Tarek307 Tarek307 is offline
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Mein Auto: 09' 650i
I accesssed my secret menu- voltage high 13s and 14 and I have random bs still appearing so sadly it looks like its not the alternator since voltage is good
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