Rear window heater/defogger not working

Hi

I'm out of ideas. I've realised that my rear window heater isn't working. When I click on the button it lights up for about 1 second and switches off. So far I've checked all connections and coding, latest scan here https://forums.ross-tech.com/showthread.php?17231-Retrofit-3Q0-ABS-Pump/page7

No fault codes and it's actively coded on the bcm as far as I can see.

Any ideas?

does the module see the input from the button when pressed every time thereafter ? if so try recoding the module with the same string ........

EDIT: I'm assuming you've done some testing ?

Errmm not sure what you mean. If you are referring to the measuring values then yes the button does function when pressed but the current doesn't remain active as it should do for a timed period - 600 seconds I believe. It switches off after approx 1 second. I was thinking it might be a relay fault as it's supposed to use a relay to run the rear window defogger but before I tear the car apart I thought I'd ask the question in case anyone has had a similar/identical issue.

Have you checked the rear defrost for an open loop or short causing breaker reset after the relay?

Default coding since car has retrofitted components?