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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
 
A

Arfa Daily

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
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
 
J

John Robertson

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

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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just flip out."
 
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