Intermittent dashboard blackout and engine cut whilst driving

[Yx67]

Hi,

I have a 2017 VW caddy maxi, it recently had a clutch and battery change, and then a week later the problem started

Whilst driving the lights on the dashboard started flickering, then it went fully black, no lights on dash and cut engine off, try to restart, checked battery terminals and no crank or anything then a few minutes later the lights came back on themselves and engine restarted.

The lights kept flickering but didn't go off again, took it to garage they checked alternator and said it's weak, so put a new alternator in but then the same above kept happening but more frequently. This time called AA by the time they came out had come back on but they checked and said there's a code for fuel pressure, so changed the fuel pressure rail.

However this didn't fix it either, took it back to the garage and he was sure that it was ignition starter switch. He changed that but it still didn't help.

Anyone experienced this before or know what it could possibly be?

[STP]

It sounds like a classic loose connection.

Check the tightness of battery clamps, the earth lead to the body, the nuts on the front strip with the master fuses on the engine fusebox, the main live into the engine fusebox (main terminal is on top) all that stuff.

You have to have a loose nut or connection somewhere on the main power cables from the battery or at the fusebox itself.

Trace all cables from the battery and ensure they are tight and clean at both ends of every single one. If the ends are all clean and tightly bolted down, then pull firmly on every end to see if the crimp has let go, if the cable comes out or wiggles loose at the end, there's the issue.

If none of that is found to be wrong, check all relays in the engine bay fusebox are pressed in properly, and if that doesn't do it, then you could have a bad ignition switch or a cooked main power relay. This relay has 109 stamped on top of it. Also can be numbered 460.

Relays may have changed on the MK4 but fault finding above still applies. I've a MK3 facelift and have never looked around a MK4 so apologies if numbers are different.