Bmw e90 most loop broken after the trunk

nggrozev · 04-18-2019, 04:59 AM

Hi. I have been reading thru the forum, but cant find someone with the same problem. I have 328xi with the base stereo system, in the trunk i only have tcu and mulf2. My bluetooth, aux and usb are not working and i have the sos error, but i have sound. I did some trouble shooting with most loop cable, so i have signal to the tcu and to the mulf2, but after that the signal does not travel to the drivers feet connector. I used the loop for the mulf2 which receives signal from the tcu but still no signal at drivers feet port. I guess that i have sound in the car because i have the base system and dont have amplifier. My questions are: is there any other module between the mulf2 and the drivers feet connector that i might not know about!? And if there is nothing else between does this mean that i will have to replace the fiber cable for sure and how har that would be?

Thank you for the help in advance!

ctuna · 04-18-2019, 12:51 PM

Not likely the Fiber cables broke.
Though one guy had rodents eat his.
Easy to check shine some light in one end of them
and it comes out the other.
USB and Aux come from mulf 2 hi in cars equiped with
them.

It would help if you had Inpa and Ista D for diags and troubleshooting.

Is light coming out of one side of the radio most connector .Does it make it as
far as the Most test port.

nggrozev · 04-18-2019, 01:10 PM

Hi thank you for the reply. I found the problem today when i removed the back seat. No light was going to the most test port with both tcu and mulf2 baypassed. When i removed the seat it turned out that the seat somehow sliced one of the fiber cables that are going from the trunk to the junction fiber box. Very odd but indeed the fiber was sliced. Got it fixed with cheap used fiber cable

04-18-2019, 04:59 AM	#1
nggrozev Registered 0 Rep 2 Posts Drives: Bmw e90 lci Join Date: Apr 2019 Location: Europe iTrader: (0)	Bmw e90 most loop broken after the trunk Hi. I have been reading thru the forum, but cant find someone with the same problem. I have 328xi with the base stereo system, in the trunk i only have tcu and mulf2. My bluetooth, aux and usb are not working and i have the sos error, but i have sound. I did some trouble shooting with most loop cable, so i have signal to the tcu and to the mulf2, but after that the signal does not travel to the drivers feet connector. I used the loop for the mulf2 which receives signal from the tcu but still no signal at drivers feet port. I guess that i have sound in the car because i have the base system and dont have amplifier. My questions are: is there any other module between the mulf2 and the drivers feet connector that i might not know about!? And if there is nothing else between does this mean that i will have to replace the fiber cable for sure and how har that would be? Thank you for the help in advance!
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04-18-2019, 12:51 PM	#2
ctuna Lieutenant General 2036 Rep 13,349 Posts Drives: 325xi 06 wagon MT Join Date: Jan 2010 Location: Santa Cruz, Ca iTrader: (0)	Not likely the Fiber cables broke. Though one guy had rodents eat his. Easy to check shine some light in one end of them and it comes out the other. USB and Aux come from mulf 2 hi in cars equiped with them. It would help if you had Inpa and Ista D for diags and troubleshooting. Is light coming out of one side of the radio most connector .Does it make it as far as the Most test port.
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04-18-2019, 01:10 PM	#3
nggrozev Registered 0 Rep 2 Posts Drives: Bmw e90 lci Join Date: Apr 2019 Location: Europe iTrader: (0)	Hi thank you for the reply. I found the problem today when i removed the back seat. No light was going to the most test port with both tcu and mulf2 baypassed. When i removed the seat it turned out that the seat somehow sliced one of the fiber cables that are going from the trunk to the junction fiber box. Very odd but indeed the fiber was sliced. Got it fixed with cheap used fiber cable
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