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Guys this maybe a stupid question, but I’m looking to setup lights under my truck and in the bed that trigger off the relay when the doors open but then i also want them on a switch. can i tag in the power trigger wires from the interior lights that i tag in as well as the switch power into the relay. So basically can you have two separate power trigger feeds to the one relay?
If I understand what you want to do (lights come on when door is opened and a switch to turn lights on when door is closed) you have headlight switch to turn on dome light. Wire your lights in behind door switch and it should work. You can't use two separate power sources with a 4 or 5 pin relay (backfeed) . You might be able to do it with an 8 pin potter-brumfield, I'd have to work on that one.
Ok so two power leads in on the 86 switch connector would be a no no. Thoughts were when the door was open the lights under the truck and the bed lights would be on and then when i hit the switch on the desh the lights would also turn on. Sounds like backfeed would be the power running back to the switch or back to the interior light when one is selected
Two signals can be used on pin 86 if you install a diode in one of them. That way you don't backfeed one of them. Or, you can use two relays with pin 30 on both connected to the load.
You would use a relay for the switch, and a relay for the door open signal. Then wire the output from each relay together. This way either opening the door, or flipping the switch will turn on the accessory lights. This also isolates each signal from each other.
Back when Radio Shack existed it was easy. Just get a diode. It really doesn't matter much which one. It needs to be able to handle enough current to run the relay, And it needs to not blow with ~14 volts going backward against it.
But that's about it and describes just about every diode ever made. If you do go that route just make sure you get one with a lead on each end (you don't want one that's intended to be mounted to a PC board).
And you would need two diodes, one on each feed wire. Each diode will only protect the wire it's on from back-feeding, so if you want to keep from back-feeding both circuits you need two wires.
Assuming there was a switch on the wire between the battery and the relay (about where it says "manual override switch"), then any time the "reverse light" was on it would turn on the "lights", and any time the "manual override switch" was on it would turn on both the "lights" and the "reverse light." That's the back-feeding we were talking about.
In this case a single diode (edit: I had incorrectly said "relay" originally) on the wire from the "reverse light" to the relay would prevent the only unwanted feedback. Since the "manual override switch" isn't doing anything other than turning this relay on there's nothing to feed back to there.
edit: By the way, if the circuit were just as drawn, with no switch where it says "manual override switch", then the relay, "lights" and reverse light would always be on.
Ok so just adding in a relay on the reverse line will stop the feed back. I can just join the power leads from the reverse line relay to the power leads coming from the relay on the manual override correct?
That isn't the diagram you should be using. I've done one that should work for what you want. The relays can have a common positive, because they share the same load. Calculate the fuse needed by adding up the load from each lamp you use. You shouldn't need to fuse the door switch, because there is one in the truck already. You can include a 2 amp fuse in the dash switch circuit to protect it from shorts.
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