I replaced the rear calipers on my 2012 RR. Without bleeding the brakes I started the car and turned it in the drive. It didn’t quite start as normal as the brake pedal had loads of travel. Anyway the next day whilst jacked up and with the front calipers off the car for refurb, I tried to start the engine. It wouldn’t start! It had ignition and request to press the brake to start but just wouldn’t start.

Now my question is! Does the request to press the brake before starting rely on sensing hydraulic pressure in the brake lines via the ABS pump (incidentally the wheel speed (ABS) sensors are disconnected as well) or does it simply monitor the brake light switch? 2012, FFRR Westminster TDV8 - Orkney Grey
2003, FFRR Vogue TD6 - Zambezi Silver
IIDBT

I'm going to guess it's pressure monitored. I left my Wife's fatty stood for a few weeks a while back and I had to really stand on the brakes to get it to start as all the vacuum had depleted in the braking system. I thought we had a fault at first, but then I thought, RR, nah! Drives:
2010 FFRR TdV8 Vogue - Stornoway Grey
2010 FFRR TdV8 Vogue SE - Zermatt Silver
1998 BMW E36 M3 GTII