Brake warning switch - The 1947 - Present Chevrolet & GMC Truck Message Board Network

BlouDon · 03-31-2020, 02:14 PM

There is a Brake Warning Switch on the brake balancer block of my truck with a Tan wire attached to it. This goes to a warning light on the dash.

What is this light meant to say?

**HO455** · 03-31-2020, 02:50 PM

The light will come on when one of the brake circuits isn't making as much pressure as the other one. So normally when you step on the brakes the front and rear brakes both make approximately the same pressure. Inside of the Proportioning Valve is a spool (Pressure Differential Valve in picture) that will shift away from the side with pressure to the low pressure side if the pressures are not equal.
So if the rear axle hose breaks then then pressure won't build in that circuit. Then the spool inside of the Proportioning Valve shifts and grounds the tan wire and the light lights. Warning you that something is wrong with the brakes.
Note this is not a drawing of a Proportioning Valve normally found on our trucks.

BlouDon · 03-31-2020, 03:24 PM

Quote:

Originally Posted by HO455

The light will come on when one of the brake circuits isn't making as much pressure as the other one. .

Thank you!!

**HO455** · 03-31-2020, 04:00 PM

You are welcome!

**FirstOwner69** · 03-31-2020, 04:54 PM

To add to HO455's great description, here's what the '69 owners manual says.

03-31-2020, 02:14 PM	#1
BlouDon Registered User Join Date: Feb 2019 Location: Centurion, Gauteng, South Africa Posts: 227	Brake warning switch There is a Brake Warning Switch on the brake balancer block of my truck with a Tan wire attached to it. This goes to a warning light on the dash. What is this light meant to say? __________________ Best regards, Philip Chev: '70 C10 (350 V8 / 700R4 ) & '59 Apache ( 235, 3-sp ) Jensen Interceptor '74: Mopar 440(EFI'ed) / 4L60e Jaguar: '72 E-type Coupe V12 & '74 E-type V12 Convertible & '80 XJS V12

03-31-2020, 02:50 PM	#2
HO455 Post Whore Join Date: Feb 2016 Location: Portland Oregon Posts: 10,807	Re: Brake warning switch The light will come on when one of the brake circuits isn't making as much pressure as the other one. So normally when you step on the brakes the front and rear brakes both make approximately the same pressure. Inside of the Proportioning Valve is a spool (Pressure Differential Valve in picture) that will shift away from the side with pressure to the low pressure side if the pressures are not equal. So if the rear axle hose breaks then then pressure won't build in that circuit. Then the spool inside of the Proportioning Valve shifts and grounds the tan wire and the light lights. Warning you that something is wrong with the brakes. Note this is not a drawing of a Proportioning Valve normally found on our trucks. Attached Images __________________ Thanks to Bob and Jeanie and everyone else at Superior Performance for all their great help. RIP Bob Parks. 1967 Burban the WMB,1991 S(stink)-10 Blazer,1969 GTO, 1970 Javelin, 1952 F2 Ford 4X4, 29 Model A, 72 Firebird. 85 Alfa Romeo If it breaks I didn't want it in the first place The WMB repair thread http://67-72chevytrucks.com/vboard/s...d.php?t=698377

03-31-2020, 04:00 PM	#4
HO455 Post Whore Join Date: Feb 2016 Location: Portland Oregon Posts: 10,807	Re: Brake warning switch You are welcome! __________________ Thanks to Bob and Jeanie and everyone else at Superior Performance for all their great help. RIP Bob Parks. 1967 Burban the WMB,1991 S(stink)-10 Blazer,1969 GTO, 1970 Javelin, 1952 F2 Ford 4X4, 29 Model A, 72 Firebird. 85 Alfa Romeo If it breaks I didn't want it in the first place The WMB repair thread http://67-72chevytrucks.com/vboard/s...d.php?t=698377

03-31-2020, 04:54 PM	#5
FirstOwner69 Senior Member Join Date: May 2010 Location: Wisconsin & Arizona Posts: 4,839	Re: Brake warning switch To add to HO455's great description, here's what the '69 owners manual says. Attached Images __________________ Jim



Register or Log In To remove these advertisements.

Register or Log In To remove these advertisements.