Source output stops when Ign switched on

I’m using the 12V IO to power a 12V (DRL) LED.

It works fine until I switch the ignition on, at which out the LED turns off. Resetting the M2 gets it going again.

Any hints as to what I can do in code to ‘reset’ the outputs? I’ve tried digitalWrite(PS_BUCK, LOW); then digitalWrite(PS_BUCK, HIGH); but no joy.