Replaced my whole brake system on my 73 charger, so why does the dash brake light come on when I apply the brakes. Bled the bejesus out of the master cylinder and system. New powerbooster, master cylinder, proportioning valve, hard lines, flexible lines, calipers, rear cylinders, so [Edited by Moparts - Keep it clean]. Also I might add no leaks. Car stops ok and pedal does not go to floor. Light comes on when the pedal is released and goes out when I give the brake a quick tap. Manual says that when light goes on some part of the system malfunctions. Anyone have any Ideas o how to troubleshoot this headache. Mopar rules!

Brake light switch under the pedal

I had no idea that there was another switch inbetween the proportioning valve and the brake lamp. I thought that the proportioning valve was the only switch. Thanks

Sometimes when doing brake swaps the prop valve warning light switch becomes uncentered and a quick hard stomp of the pedal will recenter it.

I think we are talking about the CLUSTER brake ligth

that light is conected to the emergency brake pedal too. so thats something to check.

HOWEVER for the way you describe, could it be siwthc or brake fluid distributor malfunction. SOMETIMES needs to be resetted. Dunno exactly the way to make it, BUT you could try, removing switch and relocating the double action piston to get centered and meet correctly with switch button

It's the warning light that tells you that there's a brake failure on one half of the system it'd be that the electrical contact in the prop valve needs to be recentered. when one side loses pressure the psi in the other side moves it over to the leaking(lower psi) side & it makes(electrical) contact & you see the red light. so now one side needs to be opened a bit & the brake pedal pushed to move the contact back to the center area. With all new stuff it just needs to be set right. I'm not sure of the exact procedure for this or how to figure which side the "contact" is over on but that's the main idea.

Ok so theres more to the story. When I recieved the new proportioning valve I noticed that it had the wrong mounting bracket so i ground off the rivet head, slipped the old bracket into position and tack welded the old bracket to the rivet. could this heat might have melted something inside?

Also, when I blead the master cylinder with the bleeder tube method i noticed that the large resevoir had much weaker outlet pressure than the the smaller resevoir.Could this have anything to do with it?

bracket removing... I don't think that made anything on dist block

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Also, when I blead the master cylinder with the bleeder tube method i noticed that the large resevoir had much weaker outlet pressure than the the smaller resevoir.Could this have anything to do with it?

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MAYBE...