Swapped out the green relay with a spare and now the light only comes on at 40+ mph and goes out when I switch off the ignition, only coming back on at 40+ again.

I've spent the afternoon in the garage and the pump didn't fire once, until I started up to move the car, so I'm kind of back where I was before I dismantled the car.

Don't think it was alarm related because it did it with my home-installed system, and continued when that had been removed and replaced by a pro installation. If another remote was interfering, would that not sound the arm/disarm bleeps? If so, I'm not getting any of those.

Didn't have time to do the sensors but will the MOT do a road test at 40+ (the car is 4x4)? Working alone, how easy is it to identify which sensor is giving me trouble?