[grannyknot]

I'm trying to track down the source of this dash brake warning light.
The photo is with the ignition on but engine not running, when the engine starts all the other warnings disappear and the brake light stays on, solid red, no blinking.
I just refreshed the whole braking system, with overhauled brake calipers, new pads, new flex hoses, fresh Motul 600 fluid.
No air is in the system, I've taken the car for a couple of mile drive and the brakes working perfectly.
I didn't replace the pad wear sensors, I should have but I have placed an order them now.
Any ideas?