This is a tricky one ...V5 wagon. Returned to parked car. Lost all electrical power, including hazards (first thought it might have been stupid security system). Recovery came, battery OK, made connection from battery -ve to throttle cable mount on motor, started and ran, so he said earthing problem. Cut out from time to time but came back, while in motion. Bought jumper leads. Next time no power I tried same trick, no luck, tried earthing to body using washer bottle mount, worked but didn’t work next time. Ran some wiring to throttle cable mount, washer bottle mount, cleaned earth connections I could see, improved things but still not right.

Took to Cotcomp, for whom it ran fine (grrrr). They ran a few new leads and cleaned things a bit more. No smoking gun. Ran fine a few days, now problem back

When it happens I turn on hazard switch so I know when I get current is flowing.

Clues:

Recently had sills welded then new wiring, switch and rear fog lamp. No electrical issue prior. Don’t think any issues after welding, but certainly after wiring.

Turning headlights on quickly seems to impose some noticeable load. At times it has precipitated complete electrical loss.

One time it struggled to maintain idle.

One time power came back just because I jiggled a crappy wire I ran from battery -ve to throttle cable mount on motor. Didn't work the next time.

Sometimes power comes back because I jiggle jumper lead connection on battery -ve.

Sometimes bumps precipitate loss of power. Possible wet weather in Edinburgh also, but can’t be sure.

Any suggestions very gratefully received.

 

Can't really suggest more than checking all your earth's making sure the wire and surface it's mating to is clean and free of dirt, there's 2 or 3 on each wing and a few that connect to the top of the inlet manifold. I'd start there and any wiring that was recently done. Could easily be a split in a wire occasionally touching metal or moisture, as you mention rear light, which if the one in the spoiler is a pretty common leak I'd definitely check there.

 

thanks, I'll have a look.