Electrical help

[airmanwilliams]

What the heck is the red and white off the switch for? I am sure I know this but for some reason I am not grasping this one. If you have power from the battery going through the fuse to the relay and onto the switch then why is there another positive and negative there by the switch that need connected to another power source?

 

[cruiseroutfit]

I'm guessing keyed power. Many light relays pull relay power from the battery but switch power from a keyed source or another switched source, i.e. high beams or headlights in general.

 

[STAG]

The + and - on the left is the power feed that when the switch is activated (switched closed circuit) it gives 12v to the magnetic coil inside the relay to close the switch in the relay, which let's the + (on the right side of your diagram) flow through the relay and go to the lights.

On the left-side + and -, the - actually goes straight to the electromagnetic coil in the relay. The + goes to the switch first, then out from to switch and to the other end of the electromagnetic coil.

 

[Bobzilla]

that's right, the red wire at the switch should receive 12V power from the fuse block key ON or OFF your choice, when the switch is activated the 12V from the switch will activate the relay coil to latch the relay, the white wire or ground from the relay to switch can be grounded to the battery or frame, it does not need to pass through the ON-OFF power switch.

The 40A relay should receive 12V power with key on, you can power the relay with key off if you choose to do so? normally you would want the 40A relay powered only when the key was on to avoid draining the battery, but most cars have the relay powered for the headlights with key off.

 

[STAG]

Yeah every car I know of you can turn the headlights on without a key in the IGN, but that's just for the main headlights, park lamps, 4-way flashers and brake lights. All other 12v requiring accessories are usually only key-on.

I ran the 12v to my backup camera directly to constant power (through a fuse though) and in 1 week of not using my hummer it completely sucked my battery dead. I didn't think that my backup camera pulled enough to do that. I pulled the fuse and it stopped the problem so I made a set of relays powered on by key-on power, for all my accessories because I don't want to be camping and have any unexpected power draws.

 

[STAG]

If you have power from the battery going through the fuse to the relay and onto the switch..

power doesn't come from the relay to the switch. Think of a relay as a draw-bridge. The guy(small-amp power) in the bridge-house flips a lever (in this case a switch on your dash) to drop the bridge down (the electromagnetic coil in the relay pulls the contacts closed and completed the circuit) and the cars (the big-amp power) can flow freely through the bridge(relay)

 

[airmanwilliams]

Thanks guys. Got it worked out, IM AN IDIOT. Put in 60 hours at work 2 weeks straight and just couldnt think. Ended up finding a great deal on a couple carling switches and cut the crappy switch off this universal harness and wired it up to one of the carling switches.