whirlpool adp4500 dishwasher. pulsing.

first of all i’ve read the similar threads from a while ago and i’m hoping someone has diagnosed this fault since.
to clear the air i’m very familiar with whirlpool dishies and the fault codes and that a seemingly continuous flash is in fact one flash = ntc.
that said here are the symptoms this thing has.

firstly you select any program and press the start button. the result is that the drain pump turns on and off like a heart beat while the start light goes on and off in time with the pump. this is not displaying an error code. it will do this all day if left on. there are no leaks at all.

of course the first thing the machine should do is run the drain pump and illuminate the start light therefore it’s as if it’s pulsing off rather than on.
i spend all week fixing stuff and get stuck on this which belongs to a mate it makes you feel like you don’t know what you’re doing. although i suppose that’s true here.