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BMW 3-Series (E90 E92) Forum
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No Sound or Audio - TCU or MOST?
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02-15-2019, 06:13 PM | #1 |
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No Sound or Audio - TCU or MOST?
Hey all,
About a month ago my audio cut out, no music, no seatbelt chime (slight blessing), no BT calls. This happened at the same time as the SOS alert. I did as much reading as I could, checked the fuses, all were good, picked up a MOST loop and got to testing. My MOST diagnostic port is under the driver side kick panel and prior to bypassing any modules there was no fiber optic light at the diagnostic port. I bypassed the amp, nothing different, then, when bypassing the TCU (I only have one unit under the trunk floor, not two like many others who have posted), I saw the fiber optic light at the diagnostic port. However, when reinstalling the diagnostic port loop piece, I still get no sound. Does anyone have any ideas? Is it possible the diagnostic port loop is bad? Is there anything else to check? I have found a used TCU with the same part number on eBay, but I am doubtful that it will give me sound back. Any help would be appreciated. Thanks |
02-16-2019, 01:21 PM | #3 |
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So i purchased an 2006 325xi and the previous owner said the nav system stopped working no power no nothing at all after the new battery was installed. I purchased the carly adapter to register the battery hoping to solve the issue. It didnt help. Ive done some research and seen prices of 5-700$ to have it sent out and repaired. Ive also seen upgrades to a cic unit costing about 700$. Do you guys think have my system upgraded to a CIC will solve my issue? This is a link to something ive found https://www.bimmer-tech.net/shop/bmw...ation-retrofit
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02-16-2019, 02:02 PM | #4 | |
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02-16-2019, 02:13 PM | #5 |
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You should start your own thread if you can.
Have you checked fuses? There is a fuse in the back of the unit in addition to the fuse behind the glove compartment. Do diags tell you anything. Carly should tell you something about functioning units and non functioning ones. It would be better if you had Inpa and Ista D as far as getting to root causes of problems. Describe all symtoms. Does the Nav Light up at all ? Till you know if the Head Unit is getting power and the amp is working don't make any further purchases. And don't start thinking about that box till you have this fixed. Because if you do a more uptodate Nav the box will not work. Last edited by ctuna; 02-16-2019 at 02:25 PM.. |
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02-16-2019, 04:36 PM | #6 | |
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02-16-2019, 05:09 PM | #7 | |
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02-16-2019, 05:20 PM | #8 |
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Not familiar with Carly but it should read 6 to 10 ecus
depending on how your car is configured. Also the bistable relay provides power to a lot of stuff. This is more than a Stereo problem. This is a power problem. electical e90 pdf http://www.google.com/url?sa=t&rct=j...,d.cGU&cad=rja http://www.google.com/url?sa=t&rct=j...85464276,d.cGU http://www.google.com/url?sa=t&rct=j...85464276,d.cGU see first pdf I believe relay 30g is the bi stable relay. https://www.newtis.info/tisv2/a/en/ Last edited by ctuna; 02-16-2019 at 05:27 PM.. |
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02-16-2019, 05:43 PM | #9 | |
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02-16-2019, 05:44 PM | #10 |
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Are you sure that you wired the battery back up correctly .
Or the other guy did. If you use battery back up when changing the battery on these it blows stuff up. Might not be the relay might be something feeding it. I would also check the battery voltage , yeah I know you said it was new but a low battery voltage can cause you a lot of ghost problems Don't take stuff for granted measure it. Last edited by ctuna; 02-16-2019 at 06:32 PM.. |
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02-16-2019, 06:26 PM | #11 |
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No im not sure. The people i purchased the car off of said the nav and radio worked before they had the battery replaced. After that it worked intermittently. It was also a backyard shop not an authorized dealership or anything. After a few days it stopped working completely.
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02-16-2019, 06:43 PM | #12 |
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Works before the battery change doesn't work after
what's the one thing you did . If you used battery back up to change the battery it can blow stuff up in these cars . Usually fuses. Did you use battery back up? More likely a wiring error at the battery. I would measure the battery doesn't matter if its new you want that out of the way. Is there 12 volts at the OBD port? Also the IBS system can turn off stuff it doesn't deem necessary if it detects a low battery and the Nav is one of those things. The IBS can really cause you to chase your tail. Read the first electrical pdf. https://www.google.com/search?client...e90+30g+relay+ Last edited by ctuna; 02-16-2019 at 06:58 PM.. |
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02-16-2019, 07:18 PM | #13 | |
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02-16-2019, 08:26 PM | #14 |
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You need to do basic voltage checks before you do anything
with the Most Bus your logic is not sound. They changed your battery and now you have electrical problems . If you let somebody like autozone or a non BMW shop replace your battery they are well known for screwing up the electrical system. Until you can read the ECU's with Carly and they come up OK the Most Bus is not the issue. Don't shotgun this problem. For a sanity check if you know somebody with another Car you might check to see if Carly still works. Start measuring where you have at least 12.4 Volts and where you don't . Did carly give you and OK? If you can't even run diags I don't see how it could have effectively registered the battery . but that is not your current problem. Maybe you should find a BMW Indy locally. So I take it you did not put the Battery in either. Do not take these cars to non BMW shops for anything but tires. Last edited by ctuna; 02-16-2019 at 08:33 PM.. |
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02-16-2019, 08:36 PM | #15 | |
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02-16-2019, 08:52 PM | #16 |
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Pre 03/07 CCC units fail all the time. I would replace it with a post 03/2007 CCC.
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02-16-2019, 08:52 PM | #17 |
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I beieve Carly reads your battery voltage if it can
communicate at all . Clear codes and rerun diags if possible . But you will need a voltmeter to get down to details. Also they has no power at all, to the head unit he has a terminal 30g fail . Can't read any ECU's or DME doesn't seems like the head unit is not the issue, at this point. Last edited by ctuna; 02-17-2019 at 04:52 PM.. |
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02-17-2019, 10:27 AM | #18 | |
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14.8 while running idle AT battery also here are some screen shots. |
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02-17-2019, 01:20 PM | #19 |
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Your battery voltage is low
Cold weather is hard on batterys plus you can not let these cars set or only drive them short distances without owning a battery tender and using it. I would put a full charge on the battery from the terminals under the hood . This means a 5 hour plus charge on a trickle charger or battery tender. should be 12.4 or above. As said before if the battery voltage is low it can trigger the IBS to shut stuff off . What are the 6 or 2 fault codes? Did any come back after the reset? At least its running diags today. Last edited by ctuna; 02-17-2019 at 01:49 PM.. |
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02-17-2019, 01:38 PM | #20 | |
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02-17-2019, 01:42 PM | #21 | ||
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02-17-2019, 01:54 PM | #22 |
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Battery voltage it to Low .
Put it on a trickle charger for about 5 hours plus. and see if things improve. Charge/Jumper points are under the hood. If the Nav does not light up it could still be the IBS messing with you. |
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