not an easy question here--brake light is on - Camaro5 Chevy Camaro Forum / Camaro ZL1, SS and V6 Forums

David campbell · 09-12-2023, 05:47 PM

Who knows the brake system? the brake light indicator on my dash stays on when I pressure the brake pedal due to the combination valves switch pin in the Hydraulic Modulator Assembly staying closed, thus tripping my brake indicator light to come and stay on. service manual says its remains closed (brake light indicator on) when there is unequal brake pressure betweeen the rear and front Where do I find the source of unequal pressure?. heres a video of the problem.

https://youtu.be/-8Hsgaki-sM?si=Qeq_6of576AJRemo

what i know is this ---I assume it's a combo valve (2-way or 3-way: metering valve plus shuttle for warning of partial brake failure, and a proportional valve used when you have disk front and drum rear brakes since drums require much less hydraulic pressure than disk brakes). The shuttle (which i am pushing on and which activates the warning light) would move either forward or backward depending on whether the master cylinder front or rear internal brake piston failed (leaks, or its tiny return orifice plugged), or the shuttle would move if the front or the rear brake hydraulic pressure was different (more than is proportioned) by being either plugged or was leaking badly. In other words, if either the front OR rear brakes fail, the shuttle moves, but if both front and rear fail together it does not necessarily move. I have to center The shuttle after every brake application aka resetting it manually, is the problem in the master cylinder or in the brake system after the combo valve? i dont believe its a combo valve problem.

i have replaced the front rotors, and calipers and pads. and flushed the front brake lines and no frontend leaks found yet still no help. the brake light is still on... where to look know is the question?

09-12-2023, 05:47 PM	#1
David campbell Drives: 1997 camaro conv Join Date: Jan 2020 Location: Watertown tn Posts: 8	not an easy question here--brake light is on Who knows the brake system? the brake light indicator on my dash stays on when I pressure the brake pedal due to the combination valves switch pin in the Hydraulic Modulator Assembly staying closed, thus tripping my brake indicator light to come and stay on. service manual says its remains closed (brake light indicator on) when there is unequal brake pressure betweeen the rear and front Where do I find the source of unequal pressure?. heres a video of the problem. https://youtu.be/-8Hsgaki-sM?si=Qeq_6of576AJRemo what i know is this ---I assume it's a combo valve (2-way or 3-way: metering valve plus shuttle for warning of partial brake failure, and a proportional valve used when you have disk front and drum rear brakes since drums require much less hydraulic pressure than disk brakes). The shuttle (which i am pushing on and which activates the warning light) would move either forward or backward depending on whether the master cylinder front or rear internal brake piston failed (leaks, or its tiny return orifice plugged), or the shuttle would move if the front or the rear brake hydraulic pressure was different (more than is proportioned) by being either plugged or was leaking badly. In other words, if either the front OR rear brakes fail, the shuttle moves, but if both front and rear fail together it does not necessarily move. I have to center The shuttle after every brake application aka resetting it manually, is the problem in the master cylinder or in the brake system after the combo valve? i dont believe its a combo valve problem. i have replaced the front rotors, and calipers and pads. and flushed the front brake lines and no frontend leaks found yet still no help. the brake light is still on... where to look know is the question?