2006 4.8is electrical issues

[WannaBeBoosted]

Hey guys, just picked up a 2006 4.8is today. Driving back during my 150 mile trip, the DSC/4×4 malfunction lights came on followed by the transmission going into a fail safe program. The abs and brake lights would also come on at the same time, but would then go off. While the brake lights were on, all my accessories would lose power, such as heated seats and wheel and the navigation screen and even the radio shut off completely. If I pulled over and turned the key off for a minute, it would be fine again for about 20-30 miles. Eventually the service engine soon light came on but I haven't had a chance to scan it. Any thoughts as to what I should look for? Or has anyone seen something similar? Love this truck otherwise!

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[Panamamike00]

What kind of condition is your battery in?

[WannaBeBoosted]

Both alternator and battery have like 600 miles on them. Based on research, I'm leading to believe the alternator installed is a dud. I have a replacement ordered so we will find out

[Panamamike00]

if you dont have a way to look and what you battery and alternator are putting out you can do it with the instrument cluster. There are a few steps to it but easy enough.

How to check the Battery Voltage in your BMW E38 E39 X5 E46 using the BMW Instrument Cluster self check feature

• Turn OFF Car.
  
  
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  Turn ON high Beam headlights for 5 minutes. This removes the surface charge for proper testing.
  
  
• 
  Turn OFF High Beam headlights.
  
  
• 
  Press and hold the Check Control button in the instrument cluster (RIGHT button), and turn the ignition key to the first position (KLR).
  
  
• 
  You will first see "Check Control OK", some seconds later you will see "Test Nr.01".
  
  
• 
  Select Test Number 1. by Pressing the left button on the instrument cluster to see the car's identification number. Add the 5 digits (not 6)
  
  
  
  
  • Add up the digits Example: A123457 will lead to 2+3+4+5+7 = 21.
    
    
  • 
    Push the right button until you see "Test Nr.19".
    
    
  • 
    Enter the total amount calculated above into this menu item using the LEFT button. When complete press the right button again. This will unlock your instrument cluster giving you full access to all of the test modes
    
    
  • 
    Using the left button select Test Number 9. System Voltage.
    
    
  • 
    Press the Right button to select. Your battery voltage will show on the High Cluster until you turn the car off again

[WannaBeBoosted]

That's all good and well, but it doesn't tell me if the battery isn't taking a charge or the alternator isn't charging it. The problem is intermittent and only happens every few days or so. Most of the time, there's no issue.

[jclausen]

I would do a full charging system check and a parasitic draw test and check for faults

[WannaBeBoosted]

What's the best way to do that? I have a DVOM but I'm not super familiar with using it.