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Switch lights on, engine cuts out

Posted: 21 Aug 2020, 13:48
by Savara
Hi All. Now this is interesting. Definitely a new one for me: I'm heading back from the MOT today and discovered that when I switch my headlights on, the engine cuts out! I'm guessing there's a short somewhere but anyone know where I might start looking?

Re: Switch lights on, engine cuts out

Posted: 22 Aug 2020, 20:44
by Cecil
Try cleaning up the earths below the ignition coil.

Re: Switch lights on, engine cuts out

Posted: 22 Aug 2020, 21:28
by Cecil
Also make sure the earth stud is in good contact with steel it is fitted to, likely rusted !

Re: Switch lights on, engine cuts out

Posted: 24 Aug 2020, 13:53
by Savara
Ok cheers. Have checked there, all tightened etc. and no difference - well I though it was sorted but now the van is cutting out at random. I have heard an electrical crackle noise from the glovebox area though when it happens. I've been told there's some earthing crown type thing in this area, is that the case? If so I can't find it..

Re: Switch lights on, engine cuts out

Posted: 24 Aug 2020, 16:39
by Mocki
Up behind the glove box, above the fuse box, on the bottom of the window 

Re: Switch lights on, engine cuts out

Posted: 26 Aug 2020, 07:48
by syncroandy
The engine cutting out as described, sound like something is causing the ignition circuit to the engine to fail. However, the headlights are powered by the X terminal, so should not be drawing power from the ignition circuit. Possibly there's a problem with the battery power input to the relay plate or ignition switch, but then, if the engine can be cranked OK, perhaps not..  I'd be suspecting one or more of the following, ignition switch, dash harness from the switch to the relay plate, the relay plate itself and connections to it. I'd suggest gaining access to these components and thoroughly inspecting them for any signs of deterioration or damage. Pay attention to the terminals at either end for corrosion or signs of overheating (melted insulation), and any poorly-done modifications. Any damage found should be repaired using materials of an appropriate spec.

Also:

https://www.google.com/search?q=auto+el ... ghton+area

Re: Switch lights on, engine cuts out

Posted: 26 Aug 2020, 19:47
by colinthefox
Quite coincidentally, I've just solved a very similar problem on Van Blanc. When I turned the headlamps on, the DashCam would stop working, my phone wouldn't charge properly, and occasionally it seemed like the starter battery was not being charged. The cause was a poor connection where the alternator wire and the wire feeding the main electrics came together. IIRC on a petrol van this would be at the starter solenoid (or maybe at the battery positive?). On my diesel it was at the battery positive. Cleaning and tightening solved the problem.

Re: Switch lights on, engine cuts out

Posted: 26 Aug 2020, 19:49
by colinthefox
Oh, and when I turned the headlights on the relays behind the glovebox would rattle!

Re: Switch lights on, engine cuts out

Posted: 07 Sep 2020, 17:02
by Savara
Sorted it - Turns out the connector at the ignition switch is missing! It's been bodged with a bunch of poorly attached crimps, poorly crimped and several the wrong size. Took a while but got all crimpy and  sorted the whole lot - yay  :D
Thanks for all the input folks!

Re: Switch lights on, engine cuts out

Posted: 12 Sep 2020, 19:53
by robertneill602
When turning the engine over, the X circuit is temporary cutout by the ignition switch. Pre 84 models using the older continental fuses only had one 16 amp relay fed circuit at fuse 10. As said in other replies the headlamps are also fed directly by the X circuit. The 68 onwards Bay models also had a dim/dip headlamp flasher relay that was discontinued with the Type 25/3 models. Also with the Bay the fuse 10 was directly fed with no relay.