zigzkidz
Full Access Member
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What is this thing? Everytime i shut my truck off a few seconds later it makes a whistle noise, its just irratating.
What is this?
- Thread starter zigzkidz
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What is this thing? Everytime i shut my truck off a few seconds later it makes a whistle noise, its just irratating.
icanfixall
Official GMM hand model
Thats the vacuum-electrical switch for your low vacuum dash alarm signal... You never want to see that lite up driving down the road with vacuum assisted brakes. A 6500 lbs crewcab does not stop very well without vac assist brakes. This is one very good reason for the hydroboost brakes...
k_williams1982
'01 Excursion 4x4
If that goes bad, will it make stopping a little harder? I've had one of these trucks "kick" the vac pump belt and know what no brakes feels like. Mine doesn't feel quite that bad, but I know they could be better.
zigzkidz
Full Access Member
i dont have a low vacum warning in my dash. I just want that whistle to go away, i think when i unplugged it the sound went away but i havent really checked
69dieselfreak
well that nice
i think the low vac warning is the park brake light on our trucks
tractorman86
Registered User
really, i guess i need to put a vacuum gauge on my truck, brake lights on dash have been on for a while. part of that problem might be that i also need to do rear slave cyls, i just did the brakes 6months ago and they seemed fine...
david85
Full Access Member
I love these "name that part" threads
Yes, thats the low vacuum warning light switch. It should activate the brake light if the vacuum drops too low. I lost vacuum assist 3 times now and had to drive home that way every time. It seems my switch doesn't work
Low brake fluid, low vacuum and the parking brake deployed are the only things that should turn on the brake light AFAIK.
Yes, thats the low vacuum warning light switch. It should activate the brake light if the vacuum drops too low. I lost vacuum assist 3 times now and had to drive home that way every time. It seems my switch doesn't work
Low brake fluid, low vacuum and the parking brake deployed are the only things that should turn on the brake light AFAIK.
The Warden
MiB Impersonator
I recall there being a pressure-differential sensor in the proportioning valve as well....set to make the light come on if the pressure difference between the front and rear brakes isn't what it's supposed to be. Too lazy to pull my shop manual out at the moment
and I COULD be mistaken....but I recall it being there...
jperecko
Diesel Ape
I have lost the belt to my vacuum pump and had to drive 30+ miles without power brakes... fun. Mountain pass+traffic... good fun. I never had any warning light come on. Guess mine does not have?
typ4
Full Access Member
they frequently fail.
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