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E90 dying overnight - 30g relay?


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Finally tearing into the issues with this new to me 2006 325xi

i left it on charge all day, and it was drawing almost 7 amps after the battery finished charging. 
 

I checked the relays and fuses and the one labeled 30g was warm to the touch, but the car had been off all day. 
 

I pulled it out and I noticed the automatic transmission gear selector light went out, which had been on whether the car was on or not. 
 

I’m not sure if the draw went down, I was measuring with a battery charger and after I opened the door it changed the power draw of course. 

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2BFD10B0-A061-4F62-882F-795DC6BBD0F5.jpeg

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Morning Eric

The indicator light beside the gear selector should go out after about 10/15 mins, allowing all systems to shut down sequentially.

If the relay is hot/warm then something is energising it or probably the internal resistance is failing allowing the start/charge system to pull current or the starter could be on it's way. As the relay is the cheap bit I would replace it first, if the replacement energises then either the starter or possibly the CAS unit has a fault. The Magneti Marelli starter on my first X5 failed first symptoms were slow cranking even with a charged battery, then battery drain issues.

Good spot

Dave

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  • 2 weeks later...

It wasn’t the relay, still goes dead just not as fast.  It’s not going to sleep for some reason. 
 

I pulled the codes, pretty much all of them are under/over voltage codes which would be expected when the battery dies. 
 

I hear something that sounds like a small fan running behind the hvac controls, is there a cooling fan in there for the navigation radio?
 

IBS sensor is hooked up now, we drove it for 17 hours straight (825 miles) and that seemed to fix the IBS issue.  After the 17 hour drive, it started but cranked slowly the next day. 

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Morning Eric

Try pulling the FSR plugs (Final Stage Resistor) or Hedgehog as it is some times called. See if that cures the drain

Dave

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  • 3 weeks later...

Thank you for taking the time to help with this.  

How do I get to the FSR plug?  I can see the edge of it but I can't figure out how to unplug it.  

 

I also got the full Carly adapter and ran full diagnostics on it, and attempted to register the battery which the used car dealer told me was new (but he didn't have the tool to register the battery).  Attempts at registering the battery with Carly fail almost instantly.  About half the time it will only start if the IBS is unplugged as well.  

2F80
2E98 - Generator, communication
2DEC - Power management, battery
2E8E - IBS, communication

Others that look like they have nothing to do with this or are related to the low voltage:

55C3 - VCSG-Wheel-notlaufregulung activated, no DXC target torque
A118 - Signal detection speed error
5EBA - Steering angle sensor status error
C998 - Radtoleranzabgleich plausibility
A468 - Energy - saving mode active / No LVDS signal
E587 - K-Can controller bus off
E18F - Central registry does not match the target
A670 - Error fogging sensor / BSS error
A092 - SHD normalization
 

 

These codes were persistent after several drive cycles and reset cycles

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Hi Eric

I had an alternator issue with one of the Mercedes, symptom were battery dying overnight that was blamed initially on the battery. It was in fact the voltage regulator a diode had died allowing leak back when the engine was off draining the battery with the engine running alternator output was correct. I would get the alternator checked. I have also read that the IBS sensor and lead can cause issues.

From your codes it seems the issue is in the charging system, just need to sort which code is the cause as the other 2 could be symptoms.

I did read some time ago that the 2F80 code is a Kombi system clock plausibility issue. As I recall if the engine is turned off (current year/time stored in the DDE) then a coding session or reset to factory settings is carried out the system clock is now at model/year beginning so the DDE sees a negative amount of time between turn off and turn on, implausible so code 2F80 is triggered. I think that is it but the old grey stuff may be a bit crusty

Dave

 

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I think you’re on to something with the FSR, I noticed that when the fan is on high, it doesn’t really go on high.  I’m not sure why I haven’t noticed it before, but the fan is definitely only getting up to about 2/3 speed. 
 

IBS is probably messed up too since it won’t accept the new battery command from Carly but other codings work… sort of. 

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Morning Eric

Some times you need to reset fault codes individually a "reset all codes" wont work and certain coding isn't possible with a "fault code registered" , once all codes are clear you should be able to register the battery.

Dave

PS Change that FSR before any more coding work

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Unplugged the FSR and the transmission gear indicator light finally went out and the car started the following morning.  I'll order an aftermarket FSR for $25 and hope it works

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Some updates:

I updated the battery size and type to the correct value. It still wouldn’t register but it updated to 70AH lead acid with no issues.  It was set to 120AH, but the battery is only 140 reserve minutes (the length of time it can produce 25 amps of power) which I worked out as 66 and 2/3 amp hours.   Is it possible this 1st generation E90 (2006) doesn’t have the registration function?
 

After doing this, the car went into sleep mode very quickly, completely powering the radio off so that it took almost 60 seconds for the BMW logo to go away after starting the car, which was the intended result. 
 

additionally, the two high speed fan settings in the HVAC started working again and the heated seats are functional again as well.  
 

I think the improper battery size was driving the poor car insane, it never knew if the battery was charged or dead so it was randomly cutting 12 volt power when it shouldn’t and not cutting power when it should.  
 

If it starts in the morning, I think I can consider it fixed. 

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Hi Eric

Check realoem (if you haven't already) put your Vin and it will bring up your model check the month/year of manufacture. As far as I know the 3 range started battery registration in 2006 just not sure which month?? Realoem will confirm battery size/type

Seems your getting there now

Dave

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  • 1 month later...

I just filled the water back up in the battery and noticed this wire is unhooked, does anyone know where it goes?  Black wire coming from the positive wire

96EA1554-CB06-4BD2-94CA-940D5B8F307E.jpeg

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Morning Eric

I was told some years ago that wire is a "transport connection" only used between the factory and the Dealership it should be taped out of the way but it seems many Dealers just leave it hanging ??

My sister inlaw asked if I knew what it should be connected to, I told her the "ejector seat" don't touch it Bless she told several  friends their car could have ejector seats I haven't had the heart to tell her it was a wind up !! My brother inlaw thinks it's hilarious

Dave

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