| Vacuum pump wiring help [message #313624] |
Wed, 22 February 2017 08:44  |
Tilerpep
Messages: 404
Registered: June 2013
Location: Raleigh, NC
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On the coach I got a few weeks ago, the po installed a brake vacuum pump, but didn't quite finish. If someone has one of these, or is willing to look at the following install manual in light of my question, that would be great.
http://ssbrakes.com/attachment/63196-Instruction%20Manual
On page 7 it summarizes the wiring needed for the four pins of the relay. My install has a "Y" not pictured in the manual on the wire from relay terminal 1 to vacuum switch. One side goes to vacuum switch as shown, the other side goes up behind the dash, where there is a designated but not connected switch. Can someone confirm that the vacuum switch functions by simply grounding the circuit, and this additional wire up to the dash should function as a additional way to manually activate the pump if I just make it switch/connect to a ground behind the dash?
If my thinking is correct, the pump will always be energized to run based on the pressure switch calling for it, AND/OR if I throw the toggle in the dash it will energize it to run as long as the switch is "on".
I think my preference is for the dash toggle to energize the whole assembly/circuit, and then the pump actually cycles based on demand from the pressure switch. I would call this a master switch rather than a demand switch, but I am making up terms by logic than any common usage! If I understand how the relay works in general, to accomplish this the switch would instead be wired between the constant or ignition switched (another debate in my head) 12 volt source to terminal 2. Thoughts?
1975 Glenbrook, 1978 Royale rear bath
Raleigh, NC
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