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hooking up relay to turn off another device when turned on

I am trying to hook up a relay to turn off a light when I turn on my electric water, keep forgetting, I am sure this is a simple solution, Basically my little "IDIOT" light will be on all the time when ignition on until I turn on my switch for my fans and electric water pump on vehicle, then idiot light will turn off. I know I could hook it up for the switch and problem would be solved, but I have a temp sensor which turns it off and cools down without ignition on. thanks

Reply to
prodigy
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I guess that you just need to hook up a 12v ( assuming that it's a 12v vehicle system that we're talking here ) SPCO relay's coil between the switched feed to your pumps and fan, and vehicle ground. You then need to hook an ignition-controlled 12v supply to the normally closed relay contact, and one side of a lamp to the moving contact. The other side of the lamp goes to vehicle ground. With the ignition on, but the fan / pump switch off, current will flow through the lamp via the normally closed relay contacts, and the lamp will light. When you switch on the fan / pump switch, the relay will be energised at the same time, and the contacts will change over. There will no longer be a current path through them and the lamp, and the lamp will go out.

Arfa

Reply to
Arfa Daily

If the lamp was hooked across the two switch terminals then it would be lit when the switch is open (off) and unlit when the switch is closed, the pump and fan would act essentially as the 'common' line as they would have far less resistance than the light bulb.

I am not sure what your reference to the temp sensor means... is it in series with the switch and disables the circuit when the unit is hot?

John :-#)#

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Reply to
John Robertson

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