Starter relay main hot post

[MWbirdLOVER70]

Good morning all. So I added a vaccum pump to be able to achieve proper vaccum for my power disc brakes booster (big cam)question is it needs 12.5 volts. All my keyed on fuses 11.5 til she warms up and all my constant fuses 12.5 Was wondering if I can use the main stud on starter relay for constant voltage? Should be 12.5 volts. Pump harness is fused. Been running a toggle switch off the constant fuse on fuse box but sometimes forget to flip on when starting car and then realize no breaks backing up and then flip on. Rather than run direct to battery and looking obvious I figured starter post. Any thoughts on this set up? Thanks in advance

 

[pnora]

You can. How many amps is this drawing? Myself you could fuse a relay off the stud and your ignition keyed feed to trigger the relay.

 

[Badvert65]

t shouldn't be a problem. Personally, I would run a relay to the pump that energizes with the 'RUN' line of the key switch.
jus' sayin'

 

[MWbirdLOVER70]

Thanks guys. The pump does have a relay installed by manufacture

 

[pnora]

Looks more like a vacuum shut off switch to me not a relay.

 

[MWbirdLOVER70]

You can. How many amps is this drawing? Myself you could fuse a relay off the stud and your ignition keyed feed to trigger the relay.

Thanks Panora. I’m not sure of draw but can’t be much. Thing I don’t like is small spark as I hook up negative battery ( car sits more than driven) that’s why I was going keyed on voltage but low starting voltage didn’t meet requirements so went to toogle switch hot circuit. Not to electrical savy but can use multi tester

 

[MWbirdLOVER70]

t shouldn't be a problem. Personally, I would run a relay to the pump that energizes with the 'RUN' line of the key switch.
jus' sayin'

Thanks Badvert. Added pics of the pump. Hate that wired Hot it runs when it senses low vac ( pre set) and runs battery down over period of time so I just disconnect battery when car sits

 

[pnora]

What brand and model vacuum pump? There should be info available to tell you the amp draw.

 

[pnora]

Thanks Badvert. Added pics of the pump. Hate that wired Hot it runs when it senses low vac ( pre set) and runs battery down over period of time so I just disconnect battery when car sits

If you wire it as I suggested you will not have this problem.

 

[MWbirdLOVER70]

Looks more like a vacuum shut off switch to me not a relay.

Yes has a pressure limit switch and actual relay behind also. 15 amp inline as well

 

[MWbirdLOVER70]

What brand and model vacuum pump? There should be info available to tell you the amp draw.

Leeds through PST

 

[pnora]

15. The pump should never be connected directly to the battery or a circuit that has power when the ignition key is
off. Likewise, never connect the pump to the ignition coil or any other electrical component in the ignition
system or charging system. Confirm the circuit you choose can support 15 amps, has full battery voltage, and
only has power when the ignition key is in the on position. The circuit should not have power when the key is
turned off and removed.

 

[MWbirdLOVER70]

If you wire it as I suggested you will not have this problem.

So if I take the harness supplied with their relay and inline fuse and run directly to starter relay post I should be good to go? Sorry like I stated I can do some electrical but relays are new to me

 

[MWbirdLOVER70]

15. The pump should never be connected directly to the battery or a circuit that has power when the ignition key is
off. Likewise, never connect the pump to the ignition coil or any other electrical component in the ignition
system or charging system. Confirm the circuit you choose can support 15 amps, has full battery voltage, and
only has power when the ignition key is in the on position. The circuit should not have power when the key is
turned off and removed.

15 amp inline fuse

 

[MWbirdLOVER70]

15. The pump should never be connected directly to the battery or a circuit that has power when the ignition key is
off. Likewise, never connect the pump to the ignition coil or any other electrical component in the ignition
system or charging system. Confirm the circuit you choose can support 15 amps, has full battery voltage, and
only has power when the ignition key is in the on position. The circuit should not have power when the key is
turned off and removed.

15. The pump should never be connected directly to the battery or a circuit that has power when the ignition key is
off. Likewise, never connect the pump to the ignition coil or any other electrical component in the ignition
system or charging system. Confirm the circuit you choose can support 15 amps, has full battery voltage, and
only has power when the ignition key is in the on position. The circuit should not have power when the key is
turned off and removed.

So any keyed on circuit I found on the fuse box was all at 11.5-12.0 bolts with the exception of constant voltage like door jam switch or dome light

 

[pnora]

So if I take the harness supplied with their relay and inline fuse and run directly to starter relay post I should be good to go? Sorry like I stated I can do some electrical but relays are new to me

I just read the instructions. It does not have a keyed relay. It only has two wires hot and ground. The relay they refer to is the vacuum pressure control. So just get a 12 volt relay and wire it in with you ignition triggering the relay. That way you never have to worry about it not being activated when the motor is running.

 

[pnora]

I think you need to find someone that can help you wire it as you do not seem to grasp what is being told.

 

[MWbirdLOVER70]

I think you need to find someone that can help you wire it as you do not seem to grasp what is being told.

Yes looks like over to my buddy the guru of all things Mopar. Thanks again for all the help. It’s truely is appreciated

 

[pnora]

Yes looks like over to my buddy the guru of all things Mopar. Thanks again for all the help. It’s truely is appreciated

No problem. With that unit drawing 10 to 12 amps you do not want to wire the load into your fuse panel as it will overload the circuit. A relay is the answer. 4 wires on the relay. 1-Terminal will go to the starter relay stud and you should fuse that wire. 2-the load will be on another wire that is presently powering the pump. 3-The low amp draw wire to activate the relay can be off your 12 volt keyed ignition feed. 4-The last will be a ground wire. It is really simple to do and you will be all set up wiring it that way.

 

[MWbirdLOVER70]

No problem. With that unit drawing 10 to 12 amps you do not want to wire the load into your fuse panel as it will overload the circuit. A relay is the answer. 4 wires on the relay. 1-Terminal will go to the starter relay stud and you should fuse that wire. 2-the load will be on another wire that is presently powering the pump. 3-The low amp draw wire to activate the relay can be off your 12 volt keyed ignition feed. 4-The last will be a ground wire. It is really simple to do and you will be all set up wiring it that way.

Very cool. I think I can handle that, but what about “their” relay that I think is a relay? Do I run it in conjunction with the parts store relay?