Brake Light In Dash - The 1947 - Present Chevrolet & GMC Truck Message Board Network

orange72350 · 10-03-2003, 12:38 PM

This morning, on my way to school, the brake light in my dash came on. wasnt touching the brakes or anything, just came on. thought maybe i was low on fluid, cehcked it. it was a tiny bit low, but i still topped it off. pedal was still stiff as usual, but light is still on. any idea what causes this? thanx dale
btw its a 350/350 combo with the factory brakes. brand new claipers/pads in the front

tom hand · 10-03-2003, 12:48 PM

On 72's the brake light is also connected to the parking brake...so check the little switch under the dash before you tear into your brake system

BLACK AND BLUE 67-72 · 10-03-2003, 01:22 PM

My 72' does not have a switch for the E-Brake, it only has the wire on the proportioning valve. Supposedly the only time it will come on is if there is a problem with the brake system, meaning a change in the hydraulic pressure from what it is supposed to be. So if your rear brakes are really worn down then it could come on, also if the front brakes were worn it should also come on or if there is air in the system or a leak. Mine came on when the rear wheel cylinder started leaking, and again when the master cylinder whent bad, I replaced the master cylinder and bled the rear brakes and it went off for a while then it came on again so that probably means that I need to bleed the front calipers to get it to go off again.

gman · 10-03-2003, 05:42 PM

On a '72, is a dash light supposed to come on when the emergency brake is applied?

dinnut · 10-03-2003, 06:43 PM

my brake light is on. the rear drums are probably leaking from the master cylinder. i have no pedal until 3/4s of the way down it gets stiff. i checked the master last night and the back portion was low. i filled it and still had not much of a pedal

BLACK AND BLUE 67-72 · 10-03-2003, 06:52 PM

dinnut, that sounds like what my problem was. It was the master cylinder. And as far as I know gman I have never seen a 72' with the brake light wired to come on by depressing the E-Brake. Only on 73' and up have I ever seen them activated in that way.

1969 GMC · 10-03-2003, 07:44 PM

I have only had the brake light come one once, and that was when I was going 55-60 and one of the front brake hoses took a crap. The pedal went to the floorboard and the light came on. No brakes. Thank goodness for stick shift, though.

tom hand · 10-03-2003, 08:31 PM

My 72 has the brake light wired to the e-brake and it is factory. I have posted a picture of it before on the board. I can not find the pic but I will take another tomorrow if anyone is interested

gman · 10-04-2003, 12:03 AM

Mine has never come on so I'm wondering if it works. Thats why I questioned whether or not the light should be on with the emergency/parking brake on. My other newer cars light up with the parking brake on so it got me wondering how my '72 is supposed to work.

Tom Hand........pictures would be great. Thanks.

Jemost 72 · 10-04-2003, 04:10 AM

I went thru this a while back, changed the prop valve-light still on. Changed the wheel cyl's-light still on. Canged the master cyl-fixed the prob-light went off...

BLACK AND BLUE 67-72 · 10-04-2003, 09:37 AM

Hey, Tom I would like to see those pics also!!

sactoC10 · 10-04-2003, 10:24 AM

I recently went through 3/4 of my entire system to get that darn light to turn off. It actually did go off for a short time prior to completing all the work I did, but the fact that it came back on showed some reliability that it actually does work.

My 71 first needed some fluid, light stayed on.
Replaced front pads, light still on.
Bled the front, light stayed on.
Pushed the button on prop valve, LIGHT WENT OFF.
Front brakes still sticking after 5 mins of driving, light back on. Replaced front hoses, light still on.
Bled entire system, light STILL on!
Replaced master cylinder, light still on.
Replaced booster...
Guess what, it is off and has not yet come back on!

tom hand · 10-04-2003, 12:16 PM

Here is a pic of the switch that makes the light come on with the parking brake. It is t'd into the brown wire that goes to the prop valve with the exact same kind of connector that is used on the dome light at the fuse box.

jorgensensc · 10-04-2003, 07:22 PM

My light came on just about when my manual brakes went out. I was just as suprised that this switch still worked(looked very original) That's when I decided it was as good a time as any to go to power brakes. Changed the front calipers (completely disgusting inside after 30 years of crud) rear wheel cylinders too. Right after I got it all put together and drove it around awhile the new switch set the ligt off. Turns out it was low on fluid. I hadn't bled the system completely. Added fluid and it works great, What an amazing little switch!!! I don't have the ebrake switch on mine though. It would be nice, can't tell you how many times my brake was partially depressed and I didn't know it and drove it for a few days. Broke some rear shoes doing that!!!

gman · 10-05-2003, 12:28 AM

Tom Hand,

Thanks for the picture. Mine doesn't have that switch but I wish it did. Do you think that is original? The spot on my brake mechanism is just flat where yours is in the picture........not even a hole for the mounting of a switch. Thanks again.

BLACK AND BLUE 67-72 · 10-05-2003, 12:35 AM

Yeah, thanks Tom!! Mine does not have anything there either? Anyone know if this is factory? I have never seen it on any trucks from '67 to '72, and have not seen it in any wiring diagrams either.

10-03-2003, 12:38 PM	#1
orange72350 Registered User Join Date: Jan 2003 Location: Cold, Snowy High Level, Alberta Canada Eh Posts: 394	Brake Light In Dash This morning, on my way to school, the brake light in my dash came on. wasnt touching the brakes or anything, just came on. thought maybe i was low on fluid, cehcked it. it was a tiny bit low, but i still topped it off. pedal was still stiff as usual, but light is still on. any idea what causes this? thanx dale btw its a 350/350 combo with the factory brakes. brand new claipers/pads in the front __________________ 2003 yamaha raptor. Stock, but it still hauls!!!! 2000 skiddo mxz 700. Camoplast 1.5 inch track, jaws twin pipes, b+b can, custom built and weighted clutch, wiseco piston, high comp heads. its very fast. wow. 72 c-10 longbox. Bright Orange. Brand new 350, rv cam, performer intake, qjet, headers, 2 1/2 inch exhaust into hooker areo chamber mufflers. Body work coming soon. "dont let yer mind wander, its to little to go places by itself." "Forget the herse, cause i'll never die"-ACDC Back In Black "If It's To Loud, Yer Just Too Old" "I Love Anything Fast Enough To Do Something Stupid In" "Instant idiot, just add beer!!""

10-03-2003, 12:48 PM	#2
tom hand CCRider Join Date: Feb 2000 Location: Olive Branch,MS,USA Posts: 2,232	On 72's the brake light is also connected to the parking brake...so check the little switch under the dash before you tear into your brake system __________________ 72 GMC Sierra SWB almost finished---- 84 Softail Olive Branch MS

10-03-2003, 01:22 PM	#3
BLACK AND BLUE 67-72 Firefighter Join Date: Feb 2001 Location: Yellville, Ar, USA Posts: 1,943	My 72' does not have a switch for the E-Brake, it only has the wire on the proportioning valve. Supposedly the only time it will come on is if there is a problem with the brake system, meaning a change in the hydraulic pressure from what it is supposed to be. So if your rear brakes are really worn down then it could come on, also if the front brakes were worn it should also come on or if there is air in the system or a leak. Mine came on when the rear wheel cylinder started leaking, and again when the master cylinder whent bad, I replaced the master cylinder and bled the rear brakes and it went off for a while then it came on again so that probably means that I need to bleed the front calipers to get it to go off again. __________________ '72 Chevy SWB 350 Auto '67 GMC LWB 350 4 speed '70 Chevy 4x4 Stepside 350 Auto Yellville, Ar. USA

10-03-2003, 05:42 PM	#4
gman Registered User Join Date: Nov 2000 Location: Ogden, Utah Posts: 290	On a '72, is a dash light supposed to come on when the emergency brake is applied? __________________ 72 Chevy SWB Custom Deluxe K10, 350/SM465, PS, PB, Fact. Air 2000 Harley...Wide Glide

10-03-2003, 06:43 PM	#5
dinnut Registered User Join Date: Apr 2003 Location: missouri city, tx Posts: 4,486	my brake light is on. the rear drums are probably leaking from the master cylinder. i have no pedal until 3/4s of the way down it gets stiff. i checked the master last night and the back portion was low. i filled it and still had not much of a pedal __________________ 70 longbed 496/th400/Ford 9"

10-03-2003, 06:52 PM	#6
BLACK AND BLUE 67-72 Firefighter Join Date: Feb 2001 Location: Yellville, Ar, USA Posts: 1,943	dinnut, that sounds like what my problem was. It was the master cylinder. And as far as I know gman I have never seen a 72' with the brake light wired to come on by depressing the E-Brake. Only on 73' and up have I ever seen them activated in that way. __________________ '72 Chevy SWB 350 Auto '67 GMC LWB 350 4 speed '70 Chevy 4x4 Stepside 350 Auto Yellville, Ar. USA

10-03-2003, 07:44 PM	#7
1969 GMC Registered User Join Date: Feb 2003 Location: The Rubber City Posts: 5,498	I have only had the brake light come one once, and that was when I was going 55-60 and one of the front brake hoses took a crap. The pedal went to the floorboard and the light came on. No brakes. Thank goodness for stick shift, though. __________________ 1969 GMC K2500 1996 Honda Accord 2007 Kawasaki KLR 650

10-03-2003, 08:31 PM	#8
tom hand CCRider Join Date: Feb 2000 Location: Olive Branch,MS,USA Posts: 2,232	My 72 has the brake light wired to the e-brake and it is factory. I have posted a picture of it before on the board. I can not find the pic but I will take another tomorrow if anyone is interested __________________ 72 GMC Sierra SWB almost finished---- 84 Softail Olive Branch MS

10-04-2003, 12:03 AM	#9
gman Registered User Join Date: Nov 2000 Location: Ogden, Utah Posts: 290	Mine has never come on so I'm wondering if it works. Thats why I questioned whether or not the light should be on with the emergency/parking brake on. My other newer cars light up with the parking brake on so it got me wondering how my '72 is supposed to work. Tom Hand........pictures would be great. Thanks. __________________ 72 Chevy SWB Custom Deluxe K10, 350/SM465, PS, PB, Fact. Air 2000 Harley...Wide Glide

10-04-2003, 04:10 AM	#10
Jemost 72 Southern Bowties Join Date: Jan 2003 Location: Fort Worth, TX Posts: 240	I went thru this a while back, changed the prop valve-light still on. Changed the wheel cyl's-light still on. Canged the master cyl-fixed the prob-light went off... __________________ 1972 Cheyenne 350/350

10-04-2003, 09:37 AM	#11
BLACK AND BLUE 67-72 Firefighter Join Date: Feb 2001 Location: Yellville, Ar, USA Posts: 1,943	Hey, Tom I would like to see those pics also!! __________________ '72 Chevy SWB 350 Auto '67 GMC LWB 350 4 speed '70 Chevy 4x4 Stepside 350 Auto Yellville, Ar. USA

10-04-2003, 10:24 AM	#12
sactoC10 71 DELUX Join Date: Sep 2003 Location: Northern CA / Sac Posts: 1,055	I recently went through 3/4 of my entire system to get that darn light to turn off. It actually did go off for a short time prior to completing all the work I did, but the fact that it came back on showed some reliability that it actually does work. My 71 first needed some fluid, light stayed on. Replaced front pads, light still on. Bled the front, light stayed on. Pushed the button on prop valve, LIGHT WENT OFF. Front brakes still sticking after 5 mins of driving, light back on. Replaced front hoses, light still on. Bled entire system, light STILL on! Replaced master cylinder, light still on. Replaced booster... Guess what, it is off and has not yet come back on!

10-04-2003, 12:16 PM	#13
tom hand CCRider Join Date: Feb 2000 Location: Olive Branch,MS,USA Posts: 2,232	Here is a pic of the switch that makes the light come on with the parking brake. It is t'd into the brown wire that goes to the prop valve with the exact same kind of connector that is used on the dome light at the fuse box. Attached Images __________________ 72 GMC Sierra SWB almost finished---- 84 Softail Olive Branch MS

10-04-2003, 07:22 PM	#14
jorgensensc Registered User Join Date: Jul 2003 Location: Cypress, Tx Posts: 4,005	My light came on just about when my manual brakes went out. I was just as suprised that this switch still worked(looked very original) That's when I decided it was as good a time as any to go to power brakes. Changed the front calipers (completely disgusting inside after 30 years of crud) rear wheel cylinders too. Right after I got it all put together and drove it around awhile the new switch set the ligt off. Turns out it was low on fluid. I hadn't bled the system completely. Added fluid and it works great, What an amazing little switch!!! I don't have the ebrake switch on mine though. It would be nice, can't tell you how many times my brake was partially depressed and I didn't know it and drove it for a few days. Broke some rear shoes doing that!!! __________________ 1972 C20 Suburban- Big Blue Betty '56 Chevy Bel Air Sedan- Frame up Restoration -What would you attempt to achieve if you knew you could not fail?- -I Refuse To Tiptoe Through Life, Only To Arrive Safely At Death's Door- R.I.P. EAST SIDE LOW LIFE Last edited by jorgensensc; 10-04-2003 at 07:25 PM.

10-05-2003, 12:28 AM	#15
gman Registered User Join Date: Nov 2000 Location: Ogden, Utah Posts: 290	Tom Hand, Thanks for the picture. Mine doesn't have that switch but I wish it did. Do you think that is original? The spot on my brake mechanism is just flat where yours is in the picture........not even a hole for the mounting of a switch. Thanks again. __________________ 72 Chevy SWB Custom Deluxe K10, 350/SM465, PS, PB, Fact. Air 2000 Harley...Wide Glide



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10-05-2003, 12:35 AM	#16
BLACK AND BLUE 67-72 Firefighter Join Date: Feb 2001 Location: Yellville, Ar, USA Posts: 1,943	Yeah, thanks Tom!! Mine does not have anything there either? Anyone know if this is factory? I have never seen it on any trucks from '67 to '72, and have not seen it in any wiring diagrams either. __________________ '72 Chevy SWB 350 Auto '67 GMC LWB 350 4 speed '70 Chevy 4x4 Stepside 350 Auto Yellville, Ar. USA

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