2012 Vauxhall Meriva Not Starting - RAC Can’t Help

Mildly_Miffed

This is where we should be... doing some actual diagnosis, not just guesswork!

Next step is to start tracing the individual pins in that coil loom, seeing what and where the fault lies. Multimeter and wiring diagram time!

If you disconnect the coil pack, does it still blow?

Goudy

Just thinking out loud but if there was just a broken wire in the loom to the coil pack it would be an open circuit not a short.

Not unless it touched on another wire or ground, but you would presume they are all bound up and insulated .
Not impossible, but probable? Maybe at each end of the loom there's a possibility a loose wire shorts, or the loom itself is damaged and split open and touching something.

But it would short if the coil pack was plugged in or not.
Unplugging the coil pack wouldn't effect a short in the loom to it.


So it's the coil pack?
Maybe, but the coil pack might just be part of a route of a short from somewhere else on that circuit.
To short you need a route to ground.

That route might be the coil pack as the circuit is connected to coil pack, that's connected to the spark plugs, that are screwed into the engine and that's earthed to the car's body which is connected to the negative battery terminal.
By disconnecting the loom from the coil packs, you might be just cutting off the short.

Perhaps if you tested the resistance of the coils/coil pack will identify if the coil pack is shorting.
If it isn't then it's looks like the coil pack is part of a short circuit not THE short circuit.

SH88

Mildly_Miffed said:

This is where we should be... doing some actual diagnosis, not just guesswork!

Next step is to start tracing the individual pins in that coil loom, seeing what and where the fault lies. Multimeter and wiring diagram time!

If you disconnect the coil pack, does it still blow?

Goudy said:

Just thinking out loud but if there was just a broken wire in the loom to the coil pack it would be an open circuit not a short.

Not unless it touched on another wire or ground, but you would presume they are all bound up and insulated .
Not impossible, but probable? Maybe at each end of the loom there's a possibility a loose wire shorts, or the loom itself is damaged and split open and touching something.

But it would short if the coil pack was plugged in or not.
Unplugging the coil pack wouldn't effect a short in the loom to it.


So it's the coil pack?
Maybe, but the coil pack might just be part of a route of a short from somewhere else on that circuit.
To short you need a route to ground.

That route might be the coil pack as the circuit is connected to coil pack, that's connected to the spark plugs, that are screwed into the engine and that's earthed to the car's body which is connected to the negative battery terminal.
By disconnecting the loom from the coil packs, you might be just cutting off the short.

Perhaps if you tested the resistance of the coils/coil pack will identify if the coil pack is shorting.
If it isn't then it's looks like the coil pack is part of a short circuit not THE short circuit.

Hello.
Thanks once again for your responses and thought process.

After discovering it was only blowing the fuse when connected to the coil pack, I thought the next step would be to just replace the coil pack.
(even though the RAC guy did, but didn’t check the fuse - I figured if the fuse was already blown, the new coil pack the RAC tested on the road side wouldn’t work anyway).

So I bought one on eBay and it arrived today.

I unplugged everything, fit the new coil pack, and changed the terminal fuse, and although a bit chuggy to start with, it cranked and started.

I’ve turned it off and restarted a few times now and it’s running.

Things sound a little clicky and smells oily but I may just be imagining it.
I should probably clean the spark plugs too but I don’t have a tool long enough to reach them.
(I brushed the tops with a tooth brush though to make sure the connection was ok).

edit:
It revs fine and idles fine, but it’s still a little chuggy when it revs back down to 1000 revs for a few seconds before idling fine.
So I’ve just bought a socked extension and I plan to clean them properly tomorrow when it arrives to see if that helps even more.

Besides that, it seems the issue was mainly the coil pack (at the moment).
That said I can at least drive it to the garage now (hopefully) and have a professional look and double check.

Thanks for all your input.
I’ll leave an update if the garage say or find anything.

oldagetraveller1

"So I bought one on eBay and it arrived today."

Don't be too disappointed if that only lasts 5 minutes. No doubt some cheap Chinese knock off/tat.