C5x7 dies in traffic - what's going on?

[petef]

So, Central Glasgow, Saturday afternoon, heading for station to drop off kids after visiting at Christmas. Waiting at traffic lights.......suddenly everything dies - engine, all dash lights, heater fan... then this noise starts from the front of car, a loud strange whirring noise I've never heard before. Try to coast to kerb but inadvertently put gear lever into park so come to an abrupt halt. Blind Panic, but eventually turn ignition off and on and.....bingo, engine starts and normal service resumed. But what the hell happened?
Got home ok, some 15 miles, and ran check with Lexia - shows no fault logged. Battery connections are good, battery itself - a Yuasa - replaced not long ago. I'm completely stumped - it's as if everything in the car shorted out for a few seconds. And what on earth was that noise? Fortunately the dash cam recorded a couple of seconds of it before dying also - sorry about advertising at beginning of video
Any one any ideas??.

[GiveMeABreak]

That doesn't sound too healthy!

Sound aside, it's like the engine fuse box has and cut electrical power, but I doubt hitting Park when in motion helped any, so I do hope the gearbox is ok - it does seem so as you got home, but an unnerving experience for sure. The only time I suffered an electrical power outage was on a dual carriageway in the MKI C5. Lost everything - dash lights, audio, air con, silence - turned out it was the Comms unit under the steering wheel that was playing up. Had that replaced and fine. I don't think there are any fault codes returned for those issues though IIRC

[petef]

My first - Mk 1 - C5 had its Comm 2000 replaced when some vital functions were lost from around the steering wheel. The second - a facelift model - had a fit one day with a 'Blackpool Experience' when every light on the dash came on for a short while. This fault seems more sinister - with a quiet, sudden and complete death, albeit with immediate resurrection. What I cannot understand at all is what was making the noise? There is nothing under the bonnet that could make that kind of noise is there? - engine excepted. The hydraulic pump is relatively quiet. Perhaps some valve got stuck in a rapid recycle? EGR? turbo solenoid? Only clue I can supply is that last week I put some turbo cleaner in the fuel tank - to try and cure the ongoing over-pressure problems I have been having with the turbo. Maybe some crud got dislodged and stuck something else. But I'm really grasping at straws, but would like an answer to try and stop it from happening again.

[bobins]

I think I would - as a matter of some urgency - check the fusebox and associated wiring and electronics to check for shorts and singed bits. Fusebox 'issues' are a known problem with these and there has been a recall for this in the past.

[masood_ilyas]

Pete for what it is worth last September (2018) I had a similar blackpool experience with my Mk2 C5 on the M4 which I posted here
viewtopic.php?f=3&t=60912&p=585890&hili ... 85#p585890
but no smoking gun was ever found, one can only guess that it was a developers idea of testing software routines like a "Lamp test function" and list "All Errors" both got triggered for unknown reasons. All the connectors in the engine, gearbox and fusebox areas were checked all were sound and the errors reported on the multi screen display all were irrelevant which went away after a clearing of faults using Lexia and Reset of BSI box, touch wood it has been fine and behaved itself since.
My C5 is dated 2006 but it looks like Citroen carried on using the same ECU management software on later models.

Kind regards

Masood

[petef]

I have now checked the under bonnet fusebox and all seems ok, all wiring sound and no lingering smell of burnt electrics. Car also driving ok at the moment. Thing is Masood, there was no fault found on Lexia after the car died and no lights or any kind of power during the 'death' - except for the noise from the front. I am still none the wiser.....

[Nemo26]

If that was noise from fan, that usually means ecu failure, lost comunication etc. If that happens once again, chek sensors for absence of 5V referent voltage. If there is no 5V voltage that means that ecu doesnt have control. Before condemn ecu be sure to check all powers and grounds to ecu. Also try to disconect all sensors which share 5V referent voltage to eliminate no start because of shorter sensor.