What is this?(vacuum switch)

[BeauP]

Hey ya'll I am trying to find out what I have in my hand. The vacuum line that comes out of the valve on the brake booster goes to a round swicth mounted on the left sidewall. It is under a metal bracket, it is round with a nipple for the hose on the front has metal backing and a plug on the side. It is cracked and i need one. What is this called? Can I get it at a parts house or is it a dealer item?



ps on the back it says E T N controls division carol stream if this helps (no numbers)



Sorry, I think I have finally answered my own question after calling 3 parts houses and 2 hrs internet. NAPA calls it a Low Vacuum Warning Switch. nobody else knows that it exists I think I have read every brake post on here, but maybe this cracked little jewel will help my vacuum problem (hard petal)

 

[BeauP]

Okay maybe i finally have a worthy question. My abs and brake lights went out for the time being after i removed this switch and pluged the vacuum line going to it. Do i have to replace this switch. Brakes are the same without it, terrible :-laf

 

[DBF]

+

Sorry, I think I have finally answered my own question after calling 3 parts houses and 2 hrs internet. NAPA calls it a Low Vacuum Warning Switch. nobody else knows that it exists I think I have read every brake post on here, but maybe this cracked little jewel will help my vacuum problem (hard petal)

My 92 FSM says it only lights the Brake warning light on low vacuum.



You can unplug the hose going to that switch & put a vacuum gage on it; you should read 8. 5 to 25" varying by engine speed.



Regards, DBF

 

[cojhl2]

Deadhead the line from the pump to the booster and check the vacum. If it is OK then I would suspect the booster. If it is not OK, (15-18 In) then the pump itself is bad, or there is a bad leak in the hose from the pump to where you have the guage plugged in.



I replaced my booster a few years back . it's not too bad a job.

 

[BeauP]

Planning on borrowing a gage if it checks out good would it hurt to leave the swicth unhooked? It would save me $90. As far as the idiot light coming on I am already an expert at both feet power braking So if low vacuum occurs I will be the first to know right? I can use that money to buy a service manual then maybe I can stop asking uneducated questions.

thanks for the help

 

[Philip]

I don't think your cruise control will work with that vacuum switch unhooked.



When I bought my truck the switch was broken. The cruise would not work.

 

[dpuckett]

I dont know why the cruise wouldnt work without the switch. My cruise is currently unhooked (bad vacuum line, ironically), so I cant test that theory. Just make sure you unplug the wiring end of the switch, then there is no signal telling you it is low on vacuum. But then there may be no signal telling the PCm vacuum is good, either. Or you could try to find a used switch from a non-cruise or junkyard rig.



Daniel

 

[BeauP]

My vent selector swicth(defrost,floor or dash) is not working know. I have been digging around under the hood all weekend, can anybody confirm that the low vacuum swicth has to be installed for the a/c to function properly

 

[dpuckett]

AS far as I know, the low vacuum switch is just a warning. How does your brake pedal feel? I fit is hard, it could be your pump. If not, you have a leak (could be your switch thingie that you said was broke). Get a vacuum tester, and pump it up from the line that goes to the heater core area, and listen for leaks.



I had this same problem with both my TX trucks. It is amazing how much havoc one vacuum line can wreak. Thought I was working on a gasser for a while.



Daniel

 

[PToombs]

I don't know what vacuum level trips the switch, but check here. www.surpluscenter.com They have hobbs switches and other goodies. Maybe you can make something for $5 work!

PS- don't get lost on there!

 

[cojhl2]

My vent selector swicth(defrost,floor or dash) is not working know. I have been digging around under the hood all weekend, can anybody confirm that the low vacuum swicth has to be installed for the a/c to function properly

I had my heater controls out a few years ago and from what I understood there is no elec connection involved in the vacuum circuits. It looked like all controls were mechanical and controlled right at the switch.



This problem cannot be solved easily until you get a vacuum gauge and test the system. That vacuum pump is not a large displacement pump so a leak anywhere can allow low vacuum problems.



You gotta trace it with a guage,, my opinion,, also those gauges are not expensive.

 

[BeauP]

Update- I still have not put a gage on it yet, But the plug to the swicth has to be hooked up or the vent selector will not work. It does not matter what you do with the vacuum line.