Start/Stop + Aftermarket head unit = Hair Loss

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If I was doing this at home I would put it back to the original setup which isn't affect by the stop start but does lose it's settings then I'd find the memory wire ( yellow ) and run a permanent fused live to the battery. Then it should work through Start/Stop and retain it's settings.

Right, that's kind of how it is right now. Ignition live is from the loom, permanent live from the battery directly, due to the "timed live".

Do you still have the original HU.
If that runs no issue it points to the Sony being at fault.

I do still have it, it didn't display any issues before it was taken out, but I'd have to mess with the wires to put it back in to test now I think given the permanent live has been switched over by the installers to the dedicated one.

I know people seem to think this all points to the Sony being at fault, but it's doing exactly what it's supposed to as far as I can tell, given the wiring it has been fed, in both scenarios. If I were to try another head unit, should I be putting it in with just the standard wiring loom? Assuming it loses its settings overnight, what have we proved...the timed live of Narnia is a real thing? :)

Again, a man I spoke to on the phone (I wish I'd written his name down) at Comand seemed to think this was all normal behaviour for a 3rd party head unit. Whereas another man at Comand doesn't.
 
Again, a man I spoke to on the phone (I wish I'd written his name down) at Comand seemed to think this was all normal behaviour for a 3rd party head unit. Whereas another man at Comand doesn't.

I have never experienced this, but then I've not fitted a Sony HU.
To my mind the timed +Ve isn't that. The +Ve feed to the MB unit is permanent.
It also has canbus connectivity, I believe. With an original unit you can switch it on with the ignition off and it will time itself out, after maybe 10 minutes. Press again for another 10 minutes.
This is from memory as one of the 1st things I do is replace such with aftermatket, Chinese is my choice for reasons of the wallet and functionality.

I only ever use the loom's +Ve and pick up a switched +Ve from the ciggy lighter, that signals the HU to start up when the ignition is turned, and does what the canbus would do for the original HU.

You may save yourself going round in aimless circles by trying another HU.
 
I'm convinced it's the wiring because one thing works one way and the other works the other way.

The original fault (losing settings) was cured with a permanent live so we have the solution but it created another fault.

It's really hard because we can't see the wiring or a wiring diagram.

Everything I look at regarding the wiring of a head unit points at the three main wires ... yellow (Permanent), red (switched live), black (ground) so running a wire to the battery (depending on how it's wired should already be there as they've done it) or to a permanent live in the fuse box by the drivers door and connect the yellow wire should cure the problem because in two scenarios it already has.

For illustrative purposes only but this is a sony 16 pin diagram:

Sony.png

Edit:

Sorry I posted this before I saw you had replied

"Right, that's kind of how it is right now. Ignition live is from the loom, permanent live from the battery directly, due to the "timed live". "

There's something getting switched around there when they changed from one to the other.
 
I've just had a long conversation with Richard at Comand, here are the facts:

Yes there is a "timed live" in my particular model, not sure he calls it that, but it kicks in after 2 hours. So that part is true.
Changing the battery was a good move, but wouldn't ever fix my problem completely.
It could all be fixed now with a voltage stabiliser, however, he would want to diagnose what's happening at start (of the stop/start cycle) to see if this is indeed the problem as it could be something else.

£120 diags, £120 to code out the old unit so I get my time and date settings back, plus the cost of any potential parts.

It's a long old slog to Surrey for me, but I might do this as this has been driving me NUTS!
 
To be honest if they can't solve it I don't think anyone can.

It's a long old slog to Surrey for me, but I might do this as this has been driving me NUTS!

I can only imagine I've been looking at it for a few hours and it's driving me nuts!
 
Well, lots has happened to the World since this little debacle. I couldn't be bothered traveling to Surrey (Comand) to get this sorted, then the lockdown happened, so I took the time to remove the Sony head unit and go back to stock.

Wished I'd never bothered switching from the stock head unit, and if a company hadn't suggested they could do it for what seemed like a reasonable fee, then I certainly wouldn't have.

Anyway, back to stock head unit. Thought I should update the thread in case anyone else was ever daft enough to think it's possible without some form of wizardry to make it work.

However, and if you've read this far, congratulations, the Mercedes screen at the top of the dash no longer displays anything, rendering even the stock unit more or less useless unless all you want is the radio station that's already preset. Bluetooth, clock set and anything useful relies on the information on the screen.

Rear of screen is connected, I've checked that. I've tried pulling fuse 26, which some youtube video suggested fixes this kind of thing. I'm assuming because the battery was changed whilst the head unit was removed, the car has forgotten about the screen element? Dunno, clutching at straws.

Any suggestions?
 
Yesterday when I started my car for the first time in couple of weeks, my Pioneer head unit failed to power up. Now I have a hard wire kit installed for the dash cam that monitors battery voltage and shuts down when the voltage drops to prevent non starting due to flat battery. I let the engine idle for a couple of minutes and then restarted it and the HU powered up. No settings lost, but it took a while to seek the live traffic info and download it. I am guessing that the HU shuts down in low battery situations.
 
I probably should have started a new thread. There’s a lot of history that can be written off in this one.

This is the stock MB head unit which is working fine, the screen however isn’t.
 
Absolutely it did yes.
 

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