intermittant engine cuts off / loss of power issue

[Rasco]

Need help! Got a serious intermittent electrical fault where the car randomly shuts itself off with no warning whilst I'm driving!

the engine just shuts off, no warning, engine and electrics are all working fine and the rev counter drops off to 0 and all the electrics shut down, I pull over then when i try to restart it i get absolutely nothing when the key is in position 1 or 2 even the little red led display goes off  then after 5 mins switched off  the car seams to reset itself at key in position 1 all the dash lights come on together like the ECU is resetting itself I get and no warning EML Light afterwards like the ECU has loss all comms / power before it has a chance to record the issue its so weird, had the car over two years with no problems only thing I did recently was an oil and filter change?, just complete loss of the engine like a stall with no waning after a few minutes It starts no problem and drives ok done it three times in two days in the dealers now but they say there are no error codes and cannot replicate the fault need help!

been looking online and people with a similar fault say it could be the ignition relay? any ideas, thoughts, welcome.

 

[r5gtt]

Hi mate, check battery terminals.

[Rasco]

first thing I did, i'll double check though, the battery was replaced for a new one last year.

[r5gtt]

Check all wiring to alternator too.

[Rasco]

Checked battery voltage, with engine on and off both battery and alternator are working fine, it's not a battery issue there is charge and sufficient current to crank the engine fine, the issue is the car has an intermitant fault where you get no dash lights and nothing happens when you put the key in at all totally dead but the headlights work and the heating etc has power but the fans don't work? But on other occasions the car starts as normal no issues at all???????

[pudding]

Check VCDS if you have it.  Any faults relating to 'terminal 30' is battery / alternator related.  Any other module faults, such as the 'body control' one will also show up.

It could also be a dodgy ignition switch.   If you have a key ring that's heavy with loads of keys etc, that can cause switch failure over time.  Seen it happen with girls cars with all the crap they have dangling off a key ring.

[Rasco]

ha! that might be it you know, I'm into my EDC so I have a very small penknife and a AAA led torch on my keychain, in no way girly in fact its a macho macho keychain for a MAN! but that could be it. it would explain why when its at the dealer and they just have the key on it's own they cannot replicate the fault (although its intermittent still), I might pop to the dealer tonight and try it with the spare and then on the keychain / wiggle the ignition barrel.

what should I look for with a faulty ignition switch? is that play in the barrel? or something else?

cheers

[Rasco]

ok so the main stealer reckons they have found the issue, terminal 15 supply relay 433 apparently which is one of the two main relay in the engine bay fuse box, fingers crossed that s the end of it!

[Rasco]

appears to be fixed

[Dan_FR]

Good news! And thanks for updating the post - should be useful to anyone suffering the same issue in future 

[r5gtt]