brake warning light? Brakes work good... - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Tom · 09-09-2004, 02:51 AM

My red brake warning light came on tonight when I started up the 79. The brakes work fine, and I just changed the front pads/rotors. What causes the light to come on, fluid level, vaccum?

MylilBowTie · 09-09-2004, 03:27 AM

If I remember right its a pressure difference from front to rear.

Tom · 09-09-2004, 09:09 PM

The front brakes are new, the rears I checked and are fine, fluid level in the master cylinder is good, pedal feel and brake performance are normal. Anyone have any ideas?

screwballl · 09-10-2004, 10:01 PM

maybe its the e-brake pedal or switch?

cliffsta · 09-11-2004, 12:31 AM

thats what i thought, maybe the e brake switch is boo boo; thats the only time my brake warning light comes on, other than startup.

Fixit · 09-11-2004, 04:45 AM

If the rear brakes aren't adjusted right (to loose) it might cause a pressure difference that well cause brake switch the valve to trip.Also if the front pabs are worn.

mckpaul · 09-13-2004, 08:55 AM

I found one side of my master cylinder empty on my truck shortly after I got it, it had been sitting for a while. I filled it back up, had a little air in the lines, the pedal was a little spongy. After I changed all my dash lamps, the light was on. I unpulgged the wire on the proportional valve and the light went out. This weekend, I bled the brakes on all four wheels and got all the air out. Hooked the wire back up and the light came back on so I unpulgged it again. I went out for a test drive really testing the brakes out hard, locked up the front on the first quick stop but after that they worked better, stops quick now and almost can't lock them up. Also did some hard stops in reverse. When I came home, I also pressed the reset button on the proportional valve. When I hooked the wire back up, the light stayed off.

The proportional valve is bolted to the frame kind of below and behind the radiator on the driver side, just follow the lines from the master cylinder to locate it. It has one wire attached to it, the wire on mine comes out of the valve and goes to a disconnect a couple of inches from the valve. The reset button is on one end of the valve and is covered in rubber, kind of hard to push. Don't know if it was the fact that I got the air out of the system which got the pressure balanced on both sides of the valve or the fact that I pushed the reset button after I did that, but it's fine now.

hotrodhomi · 09-13-2004, 09:51 AM

how long after you worked on it, did the light come on? Same day? Did you bleed the system?

Tom · 09-13-2004, 09:35 PM

lol it turned out to be the emergency brake. Seeing as I've had kick panels in the way so I've never been able to use it and recently pulled them, I had no idea it set off a light

09-09-2004, 02:51 AM	#1
Tom driving is in my blood Join Date: Dec 1999 Location: Mesa AZ Posts: 5,748	brake warning light? Brakes work good... My red brake warning light came on tonight when I started up the 79. The brakes work fine, and I just changed the front pads/rotors. What causes the light to come on, fluid level, vaccum? __________________ -78 c10 short/step: 388cid, M20, 5/5 drop, lots more. Playtoy and first vehicle. -98 c1500 x-cab: 5.7L, 17" rims, 5/6 drop, flowmaster, helper bags,NBS rear disk brakes. -02 Suburban 4x4: leveled front -CBR600F4i, CBR600RR, CBR1000RR, and standup skis DISCLAIMER: I cant spell for the life of me.

09-09-2004, 03:27 AM	#2
MylilBowTie Right turn Clyde Join Date: Nov 2002 Location: Cincinnati, Ohio Posts: 2,911	If I remember right its a pressure difference from front to rear. __________________ 1974 C25 LWB: 454 4bbl Carb / TH400 / 3.73 1992 Camaro RS 305 TBI

09-10-2004, 10:01 PM	#4
screwballl Tonawanda 454 Join Date: Mar 2004 Location: Liquid Sunshine State Posts: 2,754	maybe its the e-brake pedal or switch? __________________ 91 Chevy Suburban Tonawanda 454 R2500 - SOLD!!! 04 Dodge Durango 5.7L Hemi 2WD, 24K miles (as of July 2011) In the past 30 years about 90% of Fords are still on the road, the other 10% made it home. -------------------

09-11-2004, 12:31 AM	#5
cliffsta Stepsides RULE Join Date: Jul 2004 Location: Pineville, LA Posts: 1,921	thats what i thought, maybe the e brake switch is boo boo; thats the only time my brake warning light comes on, other than startup. __________________ 1981 Chevy C10 Custom Deluxe Stepside 350 V8, headers, side exhausts, 3-speed auto SOLD 1980 Chevy C10 Custum Deluxe Stepside 305 V8, Edelbrock Performer Intake, Edelbrock 1406 600CFM 4-barrel, TH350C. Bent rod. SOLD 1984 GMC Sierra Classic Longbed 6.2L Diesel SOLD 2009 Kawasaki KLX-250S too many mods for this signature 1999 Honda Accord EX 4-cylinder, 17" Motegi Wheels 215/45/17 Sumitomo tires, Tein S-Tech lowering springs, KYB GR2 shocks, Acura TL 20mm rear swaybar, debadged, blackhoused headlights, Short-Ram Intake Cardomain of the Accord

09-13-2004, 08:55 AM	#7
mckpaul Registered User Join Date: Dec 2002 Location: Houston Posts: 300	I found one side of my master cylinder empty on my truck shortly after I got it, it had been sitting for a while. I filled it back up, had a little air in the lines, the pedal was a little spongy. After I changed all my dash lamps, the light was on. I unpulgged the wire on the proportional valve and the light went out. This weekend, I bled the brakes on all four wheels and got all the air out. Hooked the wire back up and the light came back on so I unpulgged it again. I went out for a test drive really testing the brakes out hard, locked up the front on the first quick stop but after that they worked better, stops quick now and almost can't lock them up. Also did some hard stops in reverse. When I came home, I also pressed the reset button on the proportional valve. When I hooked the wire back up, the light stayed off. The proportional valve is bolted to the frame kind of below and behind the radiator on the driver side, just follow the lines from the master cylinder to locate it. It has one wire attached to it, the wire on mine comes out of the valve and goes to a disconnect a couple of inches from the valve. The reset button is on one end of the valve and is covered in rubber, kind of hard to push. Don't know if it was the fact that I got the air out of the system which got the pressure balanced on both sides of the valve or the fact that I pushed the reset button after I did that, but it's fine now. __________________ Paul 1984 Chevy C-10 LWB/305 Last edited by mckpaul; 09-13-2004 at 08:59 AM.

09-09-2004, 09:09 PM	#3
Tom driving is in my blood Join Date: Dec 1999 Location: Mesa AZ Posts: 5,748	The front brakes are new, the rears I checked and are fine, fluid level in the master cylinder is good, pedal feel and brake performance are normal. Anyone have any ideas?

09-11-2004, 04:45 AM	#6
Fixit Registered User Join Date: Sep 2004 Location: Oneco, CT Posts: 5	If the rear brakes aren't adjusted right (to loose) it might cause a pressure difference that well cause brake switch the valve to trip.Also if the front pabs are worn.

09-13-2004, 09:51 AM	#8
hotrodhomi Registered User Join Date: Apr 2004 Location: Sacramento Posts: 3,737	how long after you worked on it, did the light come on? Same day? Did you bleed the system?

09-13-2004, 09:35 PM	#9
Tom driving is in my blood Join Date: Dec 1999 Location: Mesa AZ Posts: 5,748	lol it turned out to be the emergency brake. Seeing as I've had kick panels in the way so I've never been able to use it and recently pulled them, I had no idea it set off a light __________________ -78 c10 short/step: 388cid, M20, 5/5 drop, lots more. Playtoy and first vehicle. -98 c1500 x-cab: 5.7L, 17" rims, 5/6 drop, flowmaster, helper bags,NBS rear disk brakes. -02 Suburban 4x4: leveled front -CBR600F4i, CBR600RR, CBR1000RR, and standup skis DISCLAIMER: I cant spell for the life of me.

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