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Nick_R_23 · 04-23-2023, 06:26 PM

If the brake light is coming on, it means the shuttle valve in the proportioning valve is off to one side or the other due to one side of the hydraulic system not building pressure. Your description of symptoms seems to back this up. Either your master cylinder isn’t building pressure on one port, or you have a blockage or air in a line somewhere.

04-23-2023, 06:26 PM	#3
Nick_R_23 Registered User Join Date: May 2016 Location: Willow, Alaska Posts: 894	Re: So tell me about hydro boost, 1988 K30, pedal just about going to the floor If the brake light is coming on, it means the shuttle valve in the proportioning valve is off to one side or the other due to one side of the hydraulic system not building pressure. Your description of symptoms seems to back this up. Either your master cylinder isn’t building pressure on one port, or you have a blockage or air in a line somewhere.