2008 Leon Cupra wont start - no crank

[Ben Lucas]

Hi all I've searched the forum without any luck to my issue any help would be greatly appreciated!
I drove to work Friday without issue but when i got back to the car in the evening it would not start no crank nothing. So i thought of the obvious being battery, starter, fuses or alternator. None of these are at fault the starter will turn if i apply direct power, no lights dim and i went through all fuses with multimeter and all seem fine.

So i looked a litter deeper and found the only thing that gives any sign of power when i turn they key is the display for the aircon in the centre of the dash (lights work, horn radio, wipers etcs but that's normal) i get no display on the dash when turn key (only when i open the doors it shows) what made me think maybe the chip for the immobiliser was faulty so i got my spare key and still no luck.

The only things i can think now would be either a relay, sensor, bad earth, faulty ignition/immobiliser or fuel but the latter don't really make sense as I'm getting nowt so sounds electrical. So my question is what would be best to check next or am i missing something obvious? My knowledge is OK on the mechanical side but with electrics can get confusing, i have bought a OBD2 reader that should arrive early this week to see if its throwing up any codes.

Any help in the mean time would go a long way and thanks if you took the time to read this.

 

[Ben Lucas]

Connected OBD2 reader today that would not link to scan. Starting to think its a bad earth. Will get a bit of time this weekend to look deeper and will keep updated. Any ideas would be great!

Thanks

 

[R3k1355]

Get a proper VCDS don't mess around with a cheap OBD reader when something is properly wrong.

Have you started with the obvious like checking the battery isn't completely mullered?

 

[Ben Lucas]

Another update after reading various pages of threads regarding similar issues i tried changing relays which did not do anything. I wiggled a few earths tried to remove 460 relays(believe these to be starting relay / terminal 15 +31) but couldn't get off. so i gave up called the AA put all back together sat and waited. About 10 min went by and i thought id try start and this time it started without issue with all the old relays back in the same slots????? So i drove home and when i got home i turned the ignition off and it wouldn't turn on again completely dead i took off my seat belt and tried again and this time it started no issues, have since tried with seat belt on and off and seems to be starting fine again. This has to be a lose connection or an earth issue but where to start!?

 

[Ben Lucas]

Get a proper VCDS don't mess around with a cheap OBD reader when something is properly wrong.

Have you started with the obvious like checking the battery isn't completely mullered?

Hi thanks for the reply the battery is about 6 months old as i replaced then and i intend on getting a shop to scan this was just to try get it home.
This is looking more like a loose connection or earth as stated in my above post. a relay provides ignition switched (terminal 15) output power to pretty much all of the components in the car which need to be powered up when the ignition is switched on. I Think ill look deeper into this

Thanks again

 

[Ben Lucas]

An update as promised.


So after spending a week going through different things nothing worked changed relays the lot. Put everything back as it first was and the car started after a week of troubleshooting so was still none the wiser to the root of the problem. Today the car died again but this time the radio would turn on also which it did not on key before. So I pulled it out and found it to be really hot to touch, this is the oem radio nothing messed with. So I unplugged it then the car came into life again so I believe my problem lies in the stock head until or the wires around it. Easy fix for now is to not have it in.