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Discussion Starter · #1 ·
Hi, I have the infotainment screen constant restart issue on my 2008 Premium Luxury. I have changed out the Bluetooth module as the usual suspect with no joy.
I've got a MOST optical test loop cable on the way but just need a diagram to identify and locate the other modules to test in turn if one of them is faulty.

Any help much appreciated,

Steve


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I believe so, a plug with a fibre loop that can be removed.
 

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School time:
What's "MOST"?
 

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School time:
What's "MOST"?
MOST (Media Oriented Systems Transport) is network mostly exclusively fibre optic where high speed is needed.
 
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Definitely didn’t read this as moist first time found.


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Hi, I have the infotainment screen constant restart issue on my 2008 Premium Luxury. I have changed out the Bluetooth module as the usual suspect with no joy.
I've got a MOST optical test loop cable on the way but just need a diagram to identify and locate the other modules to test in turn if one of them is faulty.

Any help much appreciated,

Steve


Sent from my SM-G991B using Tapatalk
Infotainment section in workshop manual covers all modules on the MOST loop. The point is Most is only used to transfer data between these modules. There is no way to diagnose on MOST loop unless you disconnect each module one by one and replace that with test loop. For this purpose WM should suffice. I.e. if you disconnect one, you should have display on but some modules unavailable.

The display unit should stay on independently. Have you tried a second display unit or head unit? DTC for both should be available on Canbus available to SDD or iCarsoft.
 

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MOST (Media Oriented Systems Transport) is network mostly exclusively fibre optic where high speed is needed.
Thanks Gav.
 
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Most modern cars have multiple buses to reduce the costs associated with wiring harnesses they include stuff like;

A LIN bus (single wire IIRC) to control things like smart alternators and heated seats etc my son's Ford Fiesta 09 has this.
Also medium speed CAN Bus for devices that don't need the fastest communication
Pulse Width Modulation (PWM)
High-speed - CAN Chassis bus
High-speed CAN Powertrain bus
etc
 

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Is this what you are looking for?
 

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Discussion Starter · #11 ·
Infotainment section in workshop manual covers all modules on the MOST loop. The point is Most is only used to transfer data between these modules. There is no way to diagnose on MOST loop unless you disconnect each module one by one and replace that with test loop. For this purpose WM should suffice. I.e. if you disconnect one, you should have display on but some modules unavailable.

The display unit should stay on independently. Have you tried a second display unit or head unit? DTC for both should be available on Canbus available to SDD or iCarsoft.
Thanks Hamedhbb, really helpful. I haven't yet sourced a replacement head unit as I was looking to isolate the problem module short of taking that expensive step!
Below is what what my Icarsoft is showing when checking the fault codes...
 

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Does sound like you’ve got a break in the fibre or a faulty unit somehow breaking the loop.
The only way round this is to look at each module on the MOST ring and use the test loop :(
 
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Thanks Hamedhbb, really helpful. I haven't yet sourced a replacement head unit as I was looking to isolate the problem module short of taking that expensive step!
Below is what what my Icarsoft is showing when checking the fault codes...
I agree with Gav. Have you added anything to the system? If not I would start from modules in the boot because they are subject to more moisture. Otherwise it could be a sharply bent fibre behind the display unit to head unit. Unfortunately if it is broken away from modules, you going to need a longer fibre cable to bypass some parts of the loop.
 

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Discussion Starter · #14 ·
Thanks guys, I'm awaiting the arrival of my test loop and then start the tracing process. Good point about starting frm the boot models, much appreciated (y)
 

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Discussion Starter · #15 ·
So I'm still no closer to a solution to my constantly restarting head unit. I've replaced the unit itself along with the Bluetooth and parking module with no success. I now have a parking sensor down which causes the alarm to go off upon starting the car. Every constant restart of the head unit also causes the parking alarm sounder to go off as well - the beeping is driving me mad!
Any more thoughts guys? If anyone can tell me where the parking sounder is located at least I could silence that in the short term...

ta,

Steve
 

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Steve, have you got a PAI? and if so anything plugged into it?
 

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Discussion Starter · #19 · (Edited)
See post #10
Seems I can't open that thread - for some reason the link won't resolve? Some issue with the DNS...

UPDATE, seems my phone wont open the web link, have managed to sort that now, thanks I'll take out the front seat again and have a look at the PAI and try a MOST bypass - thanks all!
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Discussion Starter · #20 ·
So for the interest of others I finally appear to have solved the problem of my constantly restarting head unit. Using the MOST loop I went round each module and bypassed each one, finally it appears to be the DAB radio module that has been causing the issues all along. I looped out that unit and lo and behold no reboots over the last few days. Given that I don't use the DAB radio at all (I use my Echo Auto for music streaming) I just removed the offending module and all appears well. Interestingly many of the internet articles around this problem point to the DAB module being sited under the front passenger seat, however on my 2008 XF it sat on top of the navigation unit behind the n/s boot trim.
Hopefully this might help others if they encounter the same or similar issue...
 
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