SOS Warning

[Andy Collings]

Got SOS warning come on, diagnostics says no GPS signal, internal fault telematics unit. Cleared message came back after a few miles. Checked Sat Nav and GPS seems to work fine. Can put up with SOS signage but tone getting on my nerves every time I turn ignition on. Any idea's what could cause this, don't really want to go to dealership to sort, they will probably change the unit and charge a bundle. Could it be a software issue ?

[Andy Collings]

Just to note, each time I reset it. it doesn't come back till I have driven around 3-5 miles. If it was the telematics unit would it not come back straight away?

[X5Sport]

The Telematics units have rate gyros in them that need GPS to recalibrate (you lose GPS in tunnels etc) your position. If it doesn’t see the GPS to re-synch the position within a certain time frame then it alarms. They don’t use the Nav GPS receiver. SOS systems use their own dedicated GPS.

[Andy Collings]

Thanks but not sure this helps me! I can reset the warning and as I say it comes back every time after a few miles. No tunnels etc involved and only just started doing it. Had the car since April doing exactly same routes.

[X5Sport]

The point I was trying to make is it’s lost it’s GPS and it’s separate from the Nav one.. If it isn’t a faulty antenna then it will very likely be a new module. The rate gyros will allow it to work for a few minutes on dead reckoning but no GPS lock means it isn’t accurate and throws a warning. That will very likely be why it’s OK for a few minutes then errors again.

[Andy Collings]

Oh I see, great explanation, sorry missed the point first time. Will see if I can get a module from somewhere, teach me to read things properly eh! Thank you for posting again and not dismissing me as an idiot. Will post update after replacement! Cheers. Andy.

[X5Sport]

I never dismiss anyone

If it is the module it will need coding as there will very likely be vehicle specific data (VIN) needed and it may have a built in SIM card that will need correcting for you specific car. I don’t know for certain, but other manufacturers do it that way so just to be aware. It may use something different .. it’s a BMW after all!

[Andy Collings]

Thanks again, will find the unit over weekend, it's in left hand side of boot apparently. I will check part number etc and get the same one. I have read that you have to get the same one as fitted or a more up to date one. Looked on Ebay, there are several used ones on offer, some reasonable prices too. Be glad to just get rid of the warning bong. Will see how it goes and post update.

[Andy Collings]

Looked at some more posts on forums and decided at first to try easy fix of SOS warning with a MOST fibre optic loop. Basically you disconnect the connector on the TCU and put this loop onto the free connector. This didn't work as advertised on mine. I still got the warning and I lost all sound from my music system. Connected back up the TCU and music back to normal, still with SOS.
Just bought off ebay a used TCU with same part number and software but a little newer. Will fit soon and see what happens. The TCU and Amplifier and MULF are easily accessed in the left hand side of the boot, just take off the first aid kit access panel and there they are. Will change TCU soonest.

[Andy Collings]

Replaced the TCU yesterday, so far so good, no SOS message! See how it goes.

[Andy Collings]

SOS still gone, diagnostics was right, TCU internal fault. If you have the same issue read loads of threads. Don't bother with the cheaty fibre optic link, didn't work for me. Replacement TCU off Ebay was only around £40 and fixed it. Just make sure you try and get the same part number and the same production date as yours or slightly newer. My replacement was 2 months newer that's all. Was a straight forward swap with no coding required.

[libra007]

thanks, will try that for annoying message.