Geo Hahn said:
I'm not following that. Once the pressure is gone I would have thought the brake lights would be off.
This is a dual circuit brake system, and we are talking about the "Pressure Differential Warning Actuator", which lights a big red light on the dash (not the regular brake lights). The PDWA compares the pressure between the front and rear brake circuits, and lights the big red light if the pressure differential goes high enough to move the shuttle inside the PDWA. By bleeding at only one slave, the pressure on that side goes to zero, but the pressure on the other side does not.
I probably should have mentioned "firm" pressure, like trying to stop the car. It doesn't take a lot, but some.
Lots of folks assume they would know if half the brakes were not working, but it can be harder to tell than you think. When I picked up my second Stag (which has a PDWA that has been disconnected), the rear brakes were not working and apparently had been that way for longer than the PO had owned the car.
I didn't realize the problem myself until I did a brake test ... which resulted in the rear brakes finally moving and sticking on! Spent the better part of 6 hours in a Walmart parking lot, trying to get them freed up using only tools available from Walmart.