Parking Brake Lamp

[Ol Blue K20]

OK guys, I've been wanting this truck for years and my girlfriend talked the ol' guy out of it and bought it for my birthday in late Oct. I've been lurking here a while but now I have another 72 I joined. I have repaired every thing in the cluster except the parking brake lamp. The bulb is new the printed circuit is good and I tested continuity. I figured it was the switch on the pedal and when I looked I could'nt find one. So where is it? Any help would be appreciated

[Portmod7]

Pretty sure the brake lamp you are talking about is triggered by a pressure switch near the master cylinder on the engine side of the firewall.

In short, it's not a "parking brake lamp", its a light to alert you that something is wrong in your hydraulic, main braking system.

[29od1]

Originally Posted by Portmod7

Pretty sure the brake lamp you are talking about is triggered by a pressure switch near the master cylinder on the engine side of the firewall.

In short, it's not a "parking brake lamp", its a light to alert you that something is wrong in your hydraulic, main braking system.

I agree with the above.

The switch located on the top of the brake pedal is to activate the rear tail lights.

[Ol Blue K20]

I thought from memory on my k5 and k10 it also worked with the park brake. Maybe the old age is setting in. I'll try grounding the valve wire and see if it comes on, Thanks for the info

[LockDoc]

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The guys are right. It is only activated if you have trouble with your brake system. Look at your proportioning valve and you will see a brown wire hooked to it. That is the wire that supplies that light with a ground if there is a problem.

LockDoc

[Ol Blue K20]

Ok guys I just went out and grounded the wire (don't tell the boss) but you're correct it lit up. So I will correct my first statement everything in my cluster is repaired and working. LOL
Thanks Guys

[ray_mcavoy]

Originally Posted by Ol Blue K20

I thought from memory on my k5 and k10 it also worked with the park brake. Maybe the old age is setting in.

What year K5 & K10? GM did change the wiring on the "brake" warning light sometime in the late 70's or early 80's so it serves as a dual purpose light that comes on with either a hydraulic problem or with the parking brake.

To make the change, they simply added a switch to the park brake pedal assembly and wired it into the same circuit, allowing either switch to ground the brown wire and turn on the "brake" light. So it'd be easy to wire up if you would like to have the "brake" light in your 72 serve as a dual purpose indicator like it does in the newer trucks.

[Ol Blue K20]

they were both 72's. Don't tell the kids I remembered wrong they'll put me in a home LOL. But Ive been thinking about your idea about making it do dual purpose already and going to look at it later. Thanks

[jocko]

however, it COULD be a parking brake lamp if....
http://67-72chevytrucks.com/vboard/s...d.php?t=419932

Did this on my 66. Original plan was to add a small LED in the dash area as my parking brake lamp indicator - but ended up using a stock unused (except on C40+) light tube. Worked out great. But the same could be applied to 67-72 with an inconspicuous LED or bulb mounted somewhere (cuould also use dual circuit to have the dash BRAKE light indicate both (i.e. parking brake on OR single MC circuit failure. The light would still come on at start (as it should) but if it remained on, you'd know why it took so much gas to go forward... ) Just a thought.

[SS Tim]

Exactly, all you need to do is add a switch to th park brake. It would ground the brake warning lamp by tying into the wire going to the combination valve.

[Ol Blue K20]

When it quits raining here i was going to look and see what it would take to add a switch so it will be dual purpose