Odd wiring find

c210rg · 02-11-2026, 05:08 PM

I just joined and had a question for the smarter ones than myself. Car is a 2011 328i sedan. My son bought it a couple months ago. A lot of little issues we are trying to figure out, we have made good progress but still face some electrical problems.

We found some interesting wire hacks in the trunk right side by the battery. Please see picks. Don't know if this is a problem or not but wanted to know if anyone has seen this before? You can see the resistor and in the black block next to it is 2 diodes. The car has iDrive but we believe someone added it. The amp on the left side of the trunk has been modified also.

Thank you for the help.

ctuna · 02-11-2026, 05:43 PM

c210rg · 02-11-2026, 06:37 PM

Thank you for the info. We will move battery maintainer to under hood. I don't think the resistor or diodes are part of the stereo system, but of coarse not sure. We will check out the links you posted.

Just a side note he does want to sell the car when we get it sorted and doesn't have a lot of money to put into it, I'm doing the best I can to help.

ctuna · 02-12-2026, 12:01 AM

Defiantly somebody messed with it .

c210rg · 02-12-2026, 04:58 PM

Ya for sure, just trying to figure out what. I'm thinking of buying 1 month of Identifix for the car to help with the wiring. There interactive wiring diagrams might be very helpful.

ctuna · 02-12-2026, 11:57 PM

BMW used to have a free online technical bulletin with all that info.

The same database is included with Ista D the diagnostic program that BMW used for the E9x chassis. It contains a database with guided troubleshooting.
You can usually find it or get it at the coding sub forum here.

To run it requires a PC laptop , K/D can cable download and setup.
See coding sub forum .

Photonicinductor · 03-25-2026, 11:42 PM

Quote:

Originally Posted by ctuna

BMW used to have a free online technical bulletin with all that info.

The same database is included with Ista D the diagnostic program that BMW used for the E9x chassis. It contains a database with guided troubleshooting.
You can usually find it or get it at the coding sub forum here.

To run it requires a PC laptop , K/D can cable download and setup.
See coding sub forum .

You don't even need a K+Dcan cable or any form of connection to the car to view wiring diagrams in ISTA. Just pop in your VIN and you can access the wiring diagrams for your car.

02-11-2026, 05:08 PM	#1
c210rg Registered 4 Rep 3 Posts Drives: 2011 BMW 328i, 1997 BMW M3 Join Date: Feb 2026 Location: Parma Idaho iTrader: (0)	Odd wiring find I just joined and had a question for the smarter ones than myself. Car is a 2011 328i sedan. My son bought it a couple months ago. A lot of little issues we are trying to figure out, we have made good progress but still face some electrical problems. We found some interesting wire hacks in the trunk right side by the battery. Please see picks. Don't know if this is a problem or not but wanted to know if anyone has seen this before? You can see the resistor and in the black block next to it is 2 diodes. The car has iDrive but we believe someone added it. The amp on the left side of the trunk has been modified also. Thank you for the help. Attached Images
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02-11-2026, 06:37 PM	#3
c210rg Registered 4 Rep 3 Posts Drives: 2011 BMW 328i, 1997 BMW M3 Join Date: Feb 2026 Location: Parma Idaho iTrader: (0)	Thank you for the info. We will move battery maintainer to under hood. I don't think the resistor or diodes are part of the stereo system, but of coarse not sure. We will check out the links you posted. Just a side note he does want to sell the car when we get it sorted and doesn't have a lot of money to put into it, I'm doing the best I can to help.
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02-12-2026, 12:01 AM	#4
ctuna Lieutenant General 2438 Rep 14,067 Posts Drives: 325xi 06 wagon MT Join Date: Jan 2010 Location: Santa Cruz, Ca iTrader: (0)	Defiantly somebody messed with it .
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02-12-2026, 04:58 PM	#5
c210rg Registered 4 Rep 3 Posts Drives: 2011 BMW 328i, 1997 BMW M3 Join Date: Feb 2026 Location: Parma Idaho iTrader: (0)	Ya for sure, just trying to figure out what. I'm thinking of buying 1 month of Identifix for the car to help with the wiring. There interactive wiring diagrams might be very helpful.
	Appreciate 0 Quote

02-12-2026, 11:57 PM	#6
ctuna Lieutenant General 2438 Rep 14,067 Posts Drives: 325xi 06 wagon MT Join Date: Jan 2010 Location: Santa Cruz, Ca iTrader: (0)	BMW used to have a free online technical bulletin with all that info. The same database is included with Ista D the diagnostic program that BMW used for the E9x chassis. It contains a database with guided troubleshooting. You can usually find it or get it at the coding sub forum here. To run it requires a PC laptop , K/D can cable download and setup. See coding sub forum .
	Appreciate 0 Quote