Forgot to add, I had the earth cables checked and connections cleaned up two weeks ago while it was in for other bits.

 

Both earth cables.? The one between the body and engine is under the battery tray and difficult to get to.
It would be worth buying a universal earth cable for a few quid and putting it from the battery earth point on the body to somewhere on the engine, having 2 wont hurt and it eliminates an earth problem.

 

Yes Jon, the top earth is easy but as the car was going in to be under sealed I had Autolusso do the lower earth, they did the top one again for good measure.

 

I had this the other day. After a 200 mile drive, I pulled into M&S garage for some food, went back to car, put key in as the key hole surround was illuminated. Then it clicked and was absolutely dead, no interior lights, nothing.
I was perplexed because I've recently done all the earth connections. I had a quick check and the positive terminal was loose, I tightened it and it all came back to life.

I assume your terminals are tight after cleaning. I hope mine was a one off and not like yours, it's a tad concerning that the car can just die in the middle of the road at night with my kids in there.

 

All the terminals appear to be tight all around Al.
A tad concerning, I tell you its more than that when you are doing 80 on the motorway pitch black and peeing down with rain as happened to me on the first occasion, I was just so lucky to be right on an exit slip road and have very little traffic around me.

 

I think I'll put another earth lead in as John suggested. I don't wanna think about overtaking lane, 80mph, busy, dark, electrics failure. A man could get paranoid enough to put some emergency battery powered indicators in the car, with a massive red switch on the dash:biglaugh:

 

You might laugh but that might be an option if I don't get this sorted, a dozen AA batteries should do it lol.
Where would you put an extra earth point ?

 

After doing some research I opted for an Exide battery, it does what it says on the tin. Coming back to the problem I have to agree with comments made, Check, Check and check then clean all earth connections and make sure that all the positive connections are tight. You will be amazed how these things can have a bearing on your problem.
Good luck.

 

The big deal with this problem is that I don't know if Ive fixed it and won't until it goes again, it's a bit like playing Alfa Russian roulette.

 

Ah sorry I should have mentioned the hazards, they did stay powered up, it was all that saved me on that first occasion in the dark, they must have either a separate circuit or be separated from the ECUs.

Bet you all think you know where the hazard light button is don't you ? try to find it in the pitch black at panic stations in lane 3 at 80mph with your missus yelling WTF !

 

This is what I'm thinking about Hazard kit - Rocker

Looking at the picture of the rear of the unit, I assume one of the leads is the power supply and the other 2 for the + and - to the indicators. Question is, where would be a good place to splice these cables in? And assuming I could use those small security Duracell 12v batteries, how many might be needed for say 20 minutes worth of emergency power?

 

Had a new battery fitted at Autolusso on Saturday and the bloody electrics conked out again just as I got home, seems to be the 80 mile round trip that is the trigger, its always 40 odd miles out ok, stop off for a bit then lose it at around 40 miles back again.
Something is tripping out the ECUs and then requiring the battery disconnect for 20 minutes reboot.
With no reason for fault showing on the diagnostics we dont know where to go next, I have no confidence in it any more and although if it goes during the day I can still get home ok, I just cant risk going anywhere if I cant be home before dark.
As it stands I have two options and Im really looking for a third;

option one, chuck money at it not knowing what to try next and not knowing if its been fixed until it goes again.
option two, have my arse spanked by webuyanyold****dotcom and some other poor bugger comes on here asking the same questions.
option three, ?????

I just wish something would break and then I could put it in to be told its a £100 or £300 or £500 fix and I can use it properly again.

 

Sounds as if it needs real-time logging to monitor what precedes the petit-mal. Or, more old-school, pull fuses for systems that can be done without, and see if it fails or not, then put half back and try again until you can isolate the origin.

 

We're coming up to the best time to sell convertibles...

 

I dont want to sell :depressed:

 

Sounds like a bit of a nightmare, and worrying if Autolusso can't point you in the right direction.
If it was me I'd be asking around for a recommendation for an auto electrician.
Has to be something to do with the electrics, maybe something overheating and shutting down before it burns out.