sidvr6 0 Posted May 30, 2021 Hoping that someone can help me, as this has got me completely baffled... 1994 Corrado VR6 intermittently cuts out for no apparent reason: No misfire, stutter or change in engine character before it cuts out - just an instant stall, dead. Fault can happen when car is sat idling or when it's being driven, more likely to occur when car has been running for more than minutes and warmed up. Car runs perfectly outside of this fault, it's just sailed through it's MOT, emissions readings are spot on - car behaved perfectly through it's test, but stalled on it's way there and on way back after. When it cuts out there are no dash lights illuminated: oil pressure, coolant, brake, ABS warning and ignition lights all stay off. Mileage and clock stay constantly on when fault happening and don't flash off or disappear/flicker as fault happens. Car can stays 'dead' for a few minutes, re-trying to start it does nothing - no dash lights illuminate and no sounds from any relays. Other times it re-starts straight away. Car has a Scorpion 1218T alarm, which still works perfectly throughout the fault - car will arm and un-arm as normal, locking all doors and illuminating the separate dash alarm LED. Arming and un-arming the alarm does not reset or clear the fault - car stays in dead state even after this procedure... until car decides it's time to start again. There are NO faults on VCDS when scanned (apart from the normal crank sensor G28 fault code '00513 03-00 no signal' when any VR6 engine is off, which clears and stays off once started). I've recently changed the ignition switch 6N0905865 twice (Meyle) & both the ecu relay 109 and fuel pump relay 167. Also been through all the fuses. No change. I removed and checked the cars ECU yesterday, to look for any damage or burns on the main PCB - all looks perfect. In the 19 years I've owned this Corrado (and 32 years of VW ownership) I've never had a fault I can't rectify... until now. Any help or advice would be most appreciated. Quote Share this post Link to post Share on other sites
tonedef 8 Posted May 30, 2021 Until I got to the part where you said ignition switch, that was what I was thinking. Have you investigated the imobiliser reader coil? Fifteen or so years ago I had intermittent cutting out issues with mine that seemed to be cured when I messed with the coil contacts. Quote Share this post Link to post Share on other sites
fla 9 Posted May 30, 2021 Is yours and AG or CP ecu? As tonedef says it could be the ecu immobiliser if its a CP, which uses the halo coil around the steering column. When you try and start it does the engine crank or does it simply show the dash lights? If the latter its pointing to an immob fault. Quote Share this post Link to post Share on other sites
Dox 22 Posted May 30, 2021 (edited) Coil reader only reads the key chip when the key is first presented, it’s not then needed until the ecu is powered off and then the cycle is repeated? immobiliser fuse is the same as the spoiler, remove, inspect for burning and replace it anyway? immobiliser box is behind the dash, inspect its plug for burning / oxidisation/ water ingress etc Does the alarm also have its own immobiliser? If so I’d bypass it. Edited May 30, 2021 by Dox Quote Share this post Link to post Share on other sites
sidvr6 0 Posted May 30, 2021 Thanks for the response guys, much appreciated. The ECU is an AG as the car is a coilpack model but early 1994 one, so unfortunately it doesn't have the immobiliser box behind drivers side of dash or a reader coil - think it's part of the ecu circuit on AG pcb, which I visually inspected for damage. Fla, when I try restart the engine during fault it shows NO lights and does NOT crank, it stays totally dead - until the car decides it's time to play ball again, then it does everything as normal (dash lights, relays energise) and fires straight away instantly as if I've just imagined the whole cut out that's just happened. Dox, I've been through all the fuses as mentioned, checked them all with a multimeter just to be sure - all good. The alarm does have its own immobiliser (which I had wondered about) alarm functions perfectly when car is running, but also arms and disarms when car is in fault/dead mode - it could well be the immob' circuit in the alarm system unit has a dry joint or bad contact. Again, thanks guys. Quote Share this post Link to post Share on other sites
fla 9 Posted May 30, 2021 Hmm thats really a strange one. Ignition switch would give similar symptoms as you describe. But using Meyle which is a decent make shouldn't give you any issues. If there are no dash lights either it means there's no power at all. Which could mean loose connectors or wiring at the fuse box..are all the connectors properly seated and the locking clip pushed in? I'm inclined to think its something absolutely obvious, as you've replaced all the key suspects Quote Share this post Link to post Share on other sites
Cressa 44 Posted May 31, 2021 I too would consider dropping the fuse box down as fla says. Turn it and yourself so you can have a good look at all the connections. Oh these cars do test us 😡 Quote Share this post Link to post Share on other sites
1xshaunx1 27 Posted May 31, 2021 Take the battery out and check the main earth connection to the body that sits behind it toward the windscreen Quote Share this post Link to post Share on other sites
Dox 22 Posted May 31, 2021 54 minutes ago, 1xshaunx1 said: Take the battery out and check the main earth connection to the body that sits behind it toward the windscreen But he says the alarm still operates when the fault occurs, so there must be sufficient power for that? Quote Share this post Link to post Share on other sites
Dox 22 Posted May 31, 2021 Ecu power or ground issue, my focus would be on the alarms immobiliser and earth to the ecu. Quote Share this post Link to post Share on other sites
sidvr6 0 Posted June 6, 2021 Sorry for the delay... think I've sorted it! Had a good going through the wiring under the drivers side of dash, all okay. Checking behind the fusebox I found a plug not quite seated correctly, think it was plug G1 or G2 (tricky to see behind in there). Since clicking it back in correctly (& making sure the rest are seated tight) it's been as good as gold... even feels better to drive. Thank you to everyone that contributed for your time and knowledge on this issue... Cheers guys. Quote Share this post Link to post Share on other sites
Cressa 44 Posted June 6, 2021 Well done mate. Thats what we are all here for....suggestions 😂 Quote Share this post Link to post Share on other sites
tonedef 8 Posted June 6, 2021 3 hours ago, sidvr6 said: Sorry for the delay... think I've sorted it! Had a good going through the wiring under the drivers side of dash, all okay. Checking behind the fusebox I found a plug not quite seated correctly, think it was plug G1 or G2 (tricky to see behind in there). Since clicking it back in correctly (& making sure the rest are seated tight) it's been as good as gold... even feels better to drive. Thank you to everyone that contributed for your time and knowledge on this issue... Cheers guys. There should be a locking bar slides across the back of the fuse box to latch all the plugs in and stop anything like this happening. Is it missing? Quote Share this post Link to post Share on other sites
MackDM 0 Posted August 18, 2021 Good info on the fix. Good future reference. Quote Share this post Link to post Share on other sites
