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-   -   745i navigation, radio, and sound system problem (

edbmw745 01-24-2010 06:53 PM

745i navigation, radio, and sound system problem
i own a 2002 bmw 745i , the navigation system , radio system, are not working anymore, the fuses are all good, i was wondering if any one out their knows what the problem could be? please let me know thank you

Keif 01-24-2010 09:20 PM

One of the items on the MOST bus ring has tanked or you have an issue with one of the fiberoptic cables. MOST = Media Oriented Systems Transport. A MOST bus jumper / FOC coupler (fiber optic couple) - part: MOST 61 13 6 917 541 - can be used to eliminate / bypass specific devices on the network until the offender is found. Before that, try pulling out the FOC in the the glove compartment fuse box for a few seconds to give a simple MOST bus reset a shot.

edbmw745 01-25-2010 10:16 PM

thank you, im going to check it out and see what happens

Cehrlichman 03-24-2010 01:57 PM

I as well have a 2002 BMW 745i and am having the same issue. I took the MODE BUS out for a few min and plugged back in to see if it might reset the radio or navagation, nothing. I also went to BMW and asked if I should replace the MODE BUS. One of the techs I spoke with said he didn't recommend that because he didn't think that would be the cause. So I was wondering if there might be something else I can try?

*Car Problems* One night I went to start my car and the front nav screen flickered a bit. As it turned on it looked as if there was no problems. I go to accept the agreement and realize that after doing so both CD options (CD Changer/Single CD) are grayed out as well as the Radio. I scroll down to click, nothing, no sound of any sort (execpt a little crackle out of the front speakers, that happened every now and then previously). I scroll to the navigation, again nothing, just a blank screen where the nav would normally appear. Come to find out most all of the control functions dont work, with exception of the climate control. You can navigate through the menu just fine but when it comes to working nothing happens.

I've tried reseting the MOST BUS by pulling it out and plugging back in. I've tried cutting power to the entire and let it drain a bit (unpluged the battery). Not really to sure what to do from here. Any suggestions? Thank you!!

joekahng 03-24-2010 02:28 PM

any software updates lately? any new software updates on 02~03 models have triggered failure in certain control modules.

Cehrlichman 03-24-2010 02:58 PM

Not that I know of. I only bought the car last year and didn't hear about any update from previous owner. Plus it was working great for the first 6 months. Thanks!

allaboutdaz 04-09-2010 12:05 PM

any updates on this ?

Cehrlichman 04-09-2010 04:17 PM

Not yet. Any input would be great. Thanks!

TechFreak 04-09-2010 05:55 PM

Get hold of another MOST BUS LOOP Connector (same as the one in the glove box) then bypass each Control Unit in the trunk/boot... one at a time. ;)

Hopefully when you bypass the faulty control unit other functions will appear on the IDrive indicating which unit is having the problem.

Cehrlichman 04-12-2010 07:44 AM

Could you please tell me how I would go about bypassing each of the Control Units? Where exactly might they be located? I went down to BMW and asked just to borrow a MOST BUS LOOP and of course I already knew the answer before I even asked. It was "No. You must buy it.". And I of coursed ask if I could return it if it didn't work. Same answer "No". Now I have no problem going out and actually spending the $40 if thats what you think might work. What might you recommend? Again thanks for the reply.

shane2010 05-20-2010 10:36 AM

i am havin same problem please help me ........

nvafamilyman 06-07-2010 06:21 PM

Mine started this today as well, can some one explain the trouble shooting process. please advise

jide_99 06-08-2010 09:35 PM

nav not wkin
its ur radio when mine acted up, nav wasnt workin, no sound from radio, took it to a side audio and they send it off and rebuild my radio, often moisture gets in them and causes it to shut down.

nvafamilyman 06-09-2010 07:21 AM

radio probs
Thx for replying, where is the radio board located? I had my windows tinted the same day wondering if that can be the cause? Do you mind telling me what they charged to have it sent out and repaired?

jssmi765 06-15-2010 10:21 PM

If you read most of the threads here where people are having similar problems it is almost always the ASK (Audio Systems Control) unit. That is the CD player in your dash. Because everything electronic runs on the MOST BUS system if one unit goes out it appears that everything tanks. So the good news is it's probably just one component. The bad news is that the factory part is $1279 here is a link where you can get a new OEM part If you search long and hard on the internet - particularly on Ebay, you can find it cheaper used. I have found it as low as $350.

nvafamilyman 06-16-2010 08:21 AM

My problem ended up being the voice input control module, part of the optical loop for the audio system. If any of the devices on the loop go down the whole system does not work. The bad news is the part cost almost $900.

DrewBimmerGA 06-16-2010 11:26 AM


Originally Posted by nvafamilyman (Post 5262737)
My problem ended up being the voice input control module, part of the optical loop for the audio system. If any of the devices on the loop go down the whole system does not work. The bad news is the part cost almost $900.

I've been told its my voice input control module as well. I have a 2002 and it doesn't have the tray in the back to prevent moisture from getting to the compenents from the trunk hinge. They (BMW) say its water damage. I'm going to bypass it as soon as my MOST Bus jumper arrives (ordered it yesterday) and I'm taking the voice input control module to Electronic Masters (Duluth, GA) to see if they can fix it before I buy another one. They will look at it for free and they specialize in repairing car electronics.

nvafamilyman 06-16-2010 12:08 PM

let me know how it goes, I was impatient and ordered a new one:( Where did you order your MOST BUS jumper? what do those run? I am told the cd changer usually goes next.

DrewBimmerGA 06-16-2010 12:14 PM


Originally Posted by nvafamilyman (Post 5263323)
let me know how it goes, I was impatient and ordered a new one:( Where did you order your MOST BUS jumper? what do those run? I am told the cd changer usually goes next.

The first one is the jumper and the second one is the connector. I got the information off of a posting on here. I'm taking it on Friday so I'll post what happens after that.

DrewBimmerGA 06-22-2010 05:11 PM

1 Attachment(s)
Just an update. I bypassed my voice input control unit and everything is working fine. I had to modify the MOST jumper for it to fit but the service manager at the dealership told me how to do it. I cut off the end of the jumper, unplug the unit and plug this in and everything else is working (NAV, RADIO,etc). Since I never used the voice input anyway I may not even get it fixed or replace it. Here's a picture of the jumper after I modified it. I can take of picture of it connected in the car if anyone wants to see. It was very easy.

Jerry 745Li 06-22-2010 07:38 PM

Is the voice input control unit located in the trunk?

jssmi765 06-22-2010 07:41 PM


OnlySkills 06-22-2010 08:56 PM

glad you guys are getting this worked out...good luck on fixing the issue ! :thumbup:

Johnny Big 06-23-2010 01:39 PM

You are right. Mine had the same problem and BMW by passed the voice control unit for $300 and now the radio and navigation works. It would have costed $2000 if the whole thing was replaced and i figured i could do without talking to the car.

Yancboy1 07-02-2010 08:36 AM

@DrewBimmerGA Could you take a pic of it installed? i just ordered mine today and i have no idea what to do with it yet.

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