97 Silverado K1500 brake warning light

[Hawk6]

My 1997 Silverado K1500 passenger side rear brake cylinder broke on my drive home from work a few weeks ago. Lost all the brake fluid on the front reservoir in the master cylinder. Limbed the truck home only using my front brakes. I thought this would be an easy fix. Replaced both rear cylinders, bleed the brakes and we are done. Nope, brake warning light stayed on. Bleed the brakes again, had some air, but the brake warning light remain on. I then bench bleed the master cylinder, bleed the brakes once again, with some air, with no luck, brake warning light stayed on. The truck brakes are working better then ever. I bleed the brakes until no air were in the lines. Just can't figure why the warning light is still on. The ABS light is not on, the rear brake tail lights are working. I've checked to see any leaks from the master cylinder to the rear brakes, no leakage. What I have not checked is the front disc brakes to see if the pads need replacing. When I changed both front axles and ABS sensor with wheel hubs less then a year ago, pads looked great. Talking with a friend, they mentioned to change out the Brake Stop Light Lamp Switch that located above the brake pedal. I ordered the part and we'll see what happens. Can anyone relate to this problem that I'm having.
Thank you and appreciate the feedback.

 

[Hawk6]

My 1997 Silverado K1500 passenger side rear brake cylinder broke on my drive home from work a few weeks ago. Lost all the brake fluid on the front reservoir in the master cylinder. Limbed the truck home only using my front brakes. I thought this would be an easy fix. Replaced both rear cylinders, bleed the brakes and we are done. Nope, brake warning light stayed on. Bleed the brakes again, had some air, but the brake warning light remain on. I then bench bleed the master cylinder, bleed the brakes once again, with some air, with no luck, brake warning light stayed on. The truck brakes are working better then ever. I bleed the brakes until no air were in the lines. Just can't figure why the warning light is still on. The ABS light is not on, the rear brake tail lights are working. I've checked to see any leaks from the master cylinder to the rear brakes, no leakage. What I have not checked is the front disc brakes to see if the pads need replacing. When I changed both front axles and ABS sensor with wheel hubs less then a year ago, pads looked great. Talking with a friend, they mentioned to change out the Brake Stop Light Lamp Switch that located above the brake pedal. I ordered the part and we'll see what happens. Can anyone relate to this problem that I'm having.
Thank you and appreciate the feedback.

Also, there is no Master cylinder level sensor. I checked all the fuses, all good. To reset, I disconnected the battery cables for the entire day, with no luck.

 

[EJ_74]

Could be a switch. But if it came on when the cylinder went out, it's likely related. I've heard if air gets in the ABS unit it will be trapped and require a scan tool to bleed

 

[Schurkey]

The BRAKE light in the instrument cluster is triggered three ways
1. The safety switch in the combination valve. The combination valve is bolted to the ABS unit. Remove the single-wire connector from the safety switch. Does the light go out?

2. The switch on the park brake pedal assembly. Hold the park brake pedal all the way up (or disconnect the wire leading to that switch.) Does the light go out?

3. The ABS unit is unhappy. You'd have to check the service manual set for your vehicle for tips on that.

Yup, you need a scan tool to get all the air and ancient fluid out of the ABS unit. Instructions attached.

 

[GoToGuy]

You replaced the brake cylinder, good. Did you check the shoe adjustments. If there's too much shoe travel you can have too much cylinder piston travel and it will blow out.
A loss of brake pressure to one half the system will result in the safety switch shifting to the unpressurized side and turning on the " Brake " light on the instrument panel.
Rather than random answers get the Factory Service manual free here to download.

 

[Hawk6]

Appreciate everyone's feedback. Problem solved. Turns out the Brake Pressure warning switch was broken. No replacement parts were available online. Went the local salvage yard and pulled one from a 1997 C1500. You can see the picture that the tip was broken. Again thank you.