To relay or diode, that is the question. Well, firstly you need to know what role each component will play in a circuit.
A diode is meant to conduct power in one direction and has the ability to allow currents to flow through or not – depending on the direction.
Relays are switches that open and close contact points to other circuits – basically controlling a circuit by a low power signal or to control multiple circuits with one signal.
So, if you’re looking to add lights to a trailer or boat and be able to manually control them or have them come on automatically when you’re in reverse, this diagram uses a relay:
Oznium offers a relay that’d work: https://www.oznium.com/wire-12v-and-relays/relay40
Extra Information
rpaxton
Here is my project:
I am wiring a set of courtesy lights to a boat trailer. I want these lights to come on when the truck is in reverse and also be able to activate them with a manual switch in the cab.
My concern with this setup is that most automatic transmissions are shifted electrically now, and I don’t want to back feed the circuit and shift the tranny into reverse when I am not behind the wheel.
My questions is would it be easier / better to use relays wiring this circuit or diodes? Can anyone suggest a wiring diagram for this circuit?
Thanks in advance!
Rodger
Phil Oznium Owner
A diode would likely work (you’d have to make sure you get a large enough one to handle the current).
Or here’s a nice diagram for you which shows how to do it with a relay.
I’m assuming the stock reverse light circuit it positive switched (with a constantly connected ground wire).
How do you determine the size of the diode needed? I’m trying to accomplish this however when I turn my switch on the reverse lights also come on even though I have a diode in place with the banded side facing the radios reverse trigger wire. I’m using a 2 1 amp diode. On the banded side I spliced ties the two together going to the reverse trigger and on the other end (2 legs) one of my switch wires connected and the other leg is the camera/reverse light wire coming from the rear of the car. If I do it this way when I flip my switch the radios reverse trigger goes into camera mode but doesn’t show an image since the camera isn’t getting power. Any help is appreciated.