Golf MkV TDI starting issue

[jdanger61]

Hi all, looking for some help to diagnose a starting issue on my 2008 MkV 2.0 TDI DSG.

It intermittently won't start. Usually after driving for more than 30 mins then parked and turned off for 10+ mins. When it happens none of the interior/exterior lights, remote locking or instrument lights work, put the key in ignition and still nothing. Won't even crank over. Can't do anything but wait for sometimes hours! Sometimes a jolt (like slamming the door) will bring it back to life, but not always.

Very hard to diagnose, its been a local VW specialist all week and they couldn't fault it. They had already incorrectly diagnosed it as a camshaft angle sensor, but it didn't fix the problem.

Any help would be great!

Thanks

[Umai Naa!!]

Sounds like it could possibly be an ignition switch.

Also worth checking all earth points, and the big fuses on the front side of the E-box in the engine bay. Have seen a few of these where only one side of the fuse is secured, leaving the other side to make intermittant contact, and warp from the heat caused by the additional resistance.

[jdanger61]

Thanks! Will have the fuses and earths checked. The mechanic seems to also think its the ignition switch or the battery.

[vdubmotorworx]

when you try and crank are the ignition lights on or is the dash display blank? or is it lit fully and bright? or is it lit up then dims on trying to crank??..VDUB...

[jdanger61]

when you try and crank are the ignition lights on or is the dash display blank? or is it lit fully and bright? or is it lit up then dims on trying to crank??..VDUB...

The dash is normally fully blank. Sometimes it flickers but not in sink with turning the key

[vdubmotorworx]

sounds more like a loose earth fault then ...

[Golf Loon]

Did anyone clean the engine bay. I have seen an ecu connector under the rain tray with water and corrosion in it which does what you are describing.

[jdanger61]

Thanks all

I haven't had the engine bay cleaned in the two years I've owned it. It really is sounding like earth/connection faults rather than major component problems

[The One]

sounds more like a loose earth fault then ...

I'd go more towards a loose earth/dirty/corroded earth as well, doesn't seem like it could be much else, and why not start with the cheapest/easiest fix anyway.