Do I need a diode

I have my bed lights wired up and working great. It dawned on me I may need a diode. hopefully not. My switch has 2 leds one for indication powered off the 12v in for switch and then one LED for dash illumination that doesn't effect switch operation. The dash illumination LED I've tapped from the green +12v on an adjacent factory switch. I'm not really hooked up like the switch diagram. I'm tapped into always on constant 12 volts from the cab fuse panel with an add a circuit (power door locks).





here is the switch diagram. It says use diode but the way I understand it that's only if I'm using the headlight circuit for the switch power.



Thoughts?

 

Where did you get that switch

 

Air Onboard is where I got switch via Amazon.

Any one else with electrical experience wanna weight in on how I wired it and if I need a diode?

 

The Spec sheet says "This is an electronic switch....."

For Negative switched vehicles ...

The Diode is in line with the Relay's coil. When the Relay coil is de energized it may cause an induce voltage when the magnetic field collapses ( like a coil in the ignition system). The Diode prevents this "back feed". It (the Switch) may work for a while but it probably, eventually, blow the electronic circuit in the switch. = burned out switch ....

Hope that helps ??

 

Diodes are cheap no matter if you need it or not if there is any doubt install it. It will have no effect if you plan does not need it and if it does it will prevent any feed back to the lighting circuit if it is needed..

 

Ok I will install it where would I put it based in the first image if how I have it wired

 

I thought a diode was like a 'check valve' of sorts, it flows one way, buy not the other.

I don't know what positive switched circuit means, so why won't it (diode) work... school me please.

 

You are correct ... it is a one way valve ....

Try thinking this way...

You can wire a simple battery light circuit with a switch 2 ways.

1. Put the switch after the battery + terminal then to the light. Then connect the other bulb connection to ground / battery - . This way the switch is interrupting positive voltage going to the bulb from the battery (or the power does not go to the bulb until the switch is on).

2 Put the switch after the bulb and before ground. The Battery + is directly wired to the bulb terminal . This way the switch is interrupting ground to the bulb from the battery - . (or the power goes to the bulb all the time and the switch interrupts ground.

Look at the schematic you have and you can see this if you study the wire the two circuits are wired.

The reason the diode is not needed In the top circuit, the wire you would put the diode in is already grounded and you do not have to worry about induced voltage from the coil since the path to ground will take care of this ......

Also the striped end of the diode in the bottom schematic should be the end that is going to the relay. (just fyi )

 

Got it. Thanks guys.

 

So I don't need a diode. Cause 85 is grounded the way I wired it

 

How is your truck wired? Does it use negative light switching? The diode diagram's little arrow is the direction of current flow. The line drawn across the point of the arrow is the blocking side current will not flow that way.

 

My taco is a 2014 as you see above I'm running power to bed lights from fuse panel and grounding to chassis

 

What ??

 

Good for you I frankly do not know how the lights are wired there seems to be two choices that is why I posted as a question I guess I'm not quite as smart as others on this site that seem to be experts on all things Tacoma. Diodes are not all ways used as coil discharge protection they are used to prevent feed back to other circuits sharing common wiring but hey you could do that with a SPDT relay or a single 25 cent diode up to you.

 

MOST members here are very happy to assist others and also know that not everyone knows everything. Most ask that you do a search first - however, in the case of this thread, it is hard to search for a specific application question or request for clarifications (since there is so much to read/scan).

As Far as I'm concerned you are most welcome to ask any reasonable question/advice/assistance - especially to me and I'm sure MOST others....

 

I know my question requires pretty specific education/knowledge was just hoping some one very knowledgable knew for sure either way. For educations sake. Not "use one it can't hurt"

My lights are wired exactly how the first image appears at the top of this page. that's a pic I took and tested with a 9 volt battery before input it in

 

No Problemo .... If it's wired as the bottom circuit - use the diode ... It's there to protect the electronics in the switch.

 

I read what you said just wasn't sure if you noticed that I tapped into dash illumination from adjacent switch that's negative switched no? If not great thanks for the help. Also I wasn't doubting just got multiple ppl saying the complete opposite so I wasn't sure.