Passat 1.9L won't start after an attempted jump start

[TdiBlacky140]

Mate tried do jump his passat when it wouldn't start, thought it was flat battery, put a booster pack on it and something strange happened with dash lights all dimming, lights shone up again as normal when booster pack disconnected; but then wouldn't even try turn over, ignition comes on but nothing happens when hold the key in to start, it doesn't even click.

It started with a bump start and drove ok, but as soon as turned it off it wouldn't start again. Just ignition lights come up, no click or anything.

All the wires / earths from the battery down to the starter and fuse links etc.. all look ok and cleaned them anyway.
All the fuses in the cabin and in the engine bay are ok.

What's the best thing to start with, gonna check for power to the starter motor I suppose.

Can VCDS be used to help with this issue?

[philipharmes]

The battery was originally flat & probably isn't much better now.

Charge the battery slowly ( say 5 amps ) for a number of hours until you get it's voltage above 14v.

Then try starting it again.

[TdiBlacky140]

But even trying to jump it the battery doesn't even try

[Roverfan]

Yep, seen a car last week not starting even with jump leads on but with new battery it starts. They can get damaged beyond hope, not saying yours is this bad but it can happen. I wouldn't trust a battery that has been dead.

However you say there is no click and that indicates the starter solenoid not engaging, if so it points to an electrical problem with the wiring, relays, switches or the starter itself. First thing to check would be if 12v is reaching the starter (on the smaller gauge wire) when you turn the key to start

[VAG-Abound]

But even trying to jump it the battery doesn't even try

Ours was like that until I left it with a good sized, engine running "donor" vehicle connected for 10 minutes or so before trying to start it. Annoying for the neighbours but got the job done :).

After that I put a conditioning CTEK charger (https://www.ctek.com/uk/products/car/mxs-5-0-uk) on it for a couple of weeks, and it now starts normally after a week or two of non-use. It's a bit laboured at times (as it has always) been so I pop the CTEK back on occasionally for a couple of days "just in case".