1. Welcome to Tundras.com!

    You are currently viewing as a guest! To get full-access, you need to register for a FREE account.

    As a registered member, you’ll be able to:
    • Participate in all Tundra discussion topics
    • Transfer over your build thread from a different forum to this one
    • Communicate privately with other Tundra owners from around the world
    • Post your own photos in our Members Gallery
    • Access all special features of the site

Relay and the amperage going to the on/off switch

Discussion in 'Lighting' started by Cthulhu, Oct 31, 2018.

  1. Oct 31, 2018 at 1:50 PM
    #1
    Cthulhu

    Cthulhu [OP] Executive Redneck

    Joined:
    Jul 21, 2018
    Member:
    #17251
    Messages:
    795
    Gender:
    Male
    First Name:
    John
    South Carolina
    Vehicle:
    2018 Tundra Limited CM Premium Package
    Good afternoon, I PROMISE I looked for about an hour, but can't find an answer to this question on the interweb. I figured my knowledgeable friends on this forum, especially those familiar with LED light bar set-ups, can help me out!

    I am buying a 60A relay harness to use for multiple LED light bars, which utilizes only one on/off switch. It comes with a lighted on/off switch, but instead of using that one, I'd like to use one of the switches I had previously purchased (see link below), so that all my switches aesthetically look the same, i.e., non-lighted.

    All of my light bars will be pulling a combined 42A, so the relay itself should be fine.

    My question is this...the power wire that goes out of the relay to the on/off switch...will that be carrying 41A, or is the amperage "stepped down" in the relay, and the amperage is lower going to the on/off switch? I've searched and I can't seem to find where product descriptions for relays show what the outgoing amperage is, only what amperage it can handle (i.e. 40A, 60A, etc.). I just want to make sure the on/off switch I want to use in the link below can handle the juice coming from the relay, and avoid burning my Tundy to the ground!! Thanks all!!

    https://www.amazon.com/gp/product/B00VU381FW/ref=oh_aui_detailpage_o07_s00?ie=UTF8&psc=1
     
  2. Oct 31, 2018 at 3:38 PM
    #2
    NewImprovedRon

    NewImprovedRon Hey! Get off my grass!

    Joined:
    Jul 8, 2015
    Member:
    #1501
    Messages:
    13,050
    Gender:
    Male
    First Name:
    Ron
    Bentonville, AR
    Vehicle:
    2015 Radiant Red TSS Doublecab 4X4 Off Road
    Deck rail system, Bed divider, door sill protectors, LED reverse light bars, Aries Bull Bar with 28" 180 watt LED light bar, LED step lights, LED bed lights, driver-side grab handle, TRD Rear Sway Bar, BedRug bed mat and tailgate mat, Morimoto Fog Lights, more to come.....
    I assume that you are connecting your LED lights positive wire to the relay, your LED lights negative to the frame or other solid ground point, the relay to the battery positive with an in-line fuse, and the relay itself to a solid ground point. The switch itself, is connected to a "trigger" wire from your fuse box (I like to use an Add-a Fuse) and to the relay trigger wire connection. The switch carries much less power in this configuration than the total load. All it is doing is completing the circuit in your relay allowing the lights to come on. In other words, you would not want to run everything through the switch. The relay is just another switch that turns on when you turn on the dash switch on. Make sure you use a heavy enough gauge wire for your lights and relay positive and negative wires. The trigger wire from the switch to the relay, switch ground, and switch positive (fuse box) can be smaller gauge wire. I see in the switch detail that you are looking at using only a 2 pin switch. You will want to use a 3 pin switch, one wire going to the relay (trigger), one to the fuse box Add-a-fuse (switch power), and one to ground. Press the switch button and it completes the relay circuit with a reduced amperage that the switch can handle and the relay takes the heavy load.
     

    Attached Files:

    Cthulhu [OP] likes this.
  3. Oct 31, 2018 at 3:52 PM
    #3
    papasmurf

    papasmurf Savage Fabrication

    Joined:
    Jan 11, 2017
    Member:
    #5911
    Messages:
    1,887
    Gender:
    Male
    First Name:
    Bruce
    San Diego
    Vehicle:
    2007 4x4 Tundra
    07 Silver Sky 4x4 | Total Chaos LT | 2.5 King Coil overs & Bypasses | Camburg Bed Cage | 3.0 King Bypasses | 2.0 King Bumps | Custom Deavers | Nitro 4.88's | ARB Locker | Demello Sliders | 17" Double Standards | BFGKO2 37's |
    No the 12 volt lead from the switch to the relay will only carry about 1-3 amps it’s just the trigger wire to trigger the relay... it’s low amps you can use 12-18 gauge wire for that.. for the main coming off the relay going to the light bars you should use 10-8 gauge for 40-50 amps you will be pushing.
     
    Cthulhu [OP] likes this.
  4. Oct 31, 2018 at 3:53 PM
    #4
    papasmurf

    papasmurf Savage Fabrication

    Joined:
    Jan 11, 2017
    Member:
    #5911
    Messages:
    1,887
    Gender:
    Male
    First Name:
    Bruce
    San Diego
    Vehicle:
    2007 4x4 Tundra
    07 Silver Sky 4x4 | Total Chaos LT | 2.5 King Coil overs & Bypasses | Camburg Bed Cage | 3.0 King Bypasses | 2.0 King Bumps | Custom Deavers | Nitro 4.88's | ARB Locker | Demello Sliders | 17" Double Standards | BFGKO2 37's |
    Op shoot me a pm and I can draw you the circuit how it should be wired
     
  5. Oct 31, 2018 at 5:44 PM
    #5
    Cthulhu

    Cthulhu [OP] Executive Redneck

    Joined:
    Jul 21, 2018
    Member:
    #17251
    Messages:
    795
    Gender:
    Male
    First Name:
    John
    South Carolina
    Vehicle:
    2018 Tundra Limited CM Premium Package
    These answers were perfect guys! Thanks so much for your responses!!
     
    NewImprovedRon likes this.
  6. Oct 31, 2018 at 5:48 PM
    #6
    Cthulhu

    Cthulhu [OP] Executive Redneck

    Joined:
    Jul 21, 2018
    Member:
    #17251
    Messages:
    795
    Gender:
    Male
    First Name:
    John
    South Carolina
    Vehicle:
    2018 Tundra Limited CM Premium Package
  7. Nov 1, 2018 at 1:32 AM
    #7
    Cthulhu

    Cthulhu [OP] Executive Redneck

    Joined:
    Jul 21, 2018
    Member:
    #17251
    Messages:
    795
    Gender:
    Male
    First Name:
    John
    South Carolina
    Vehicle:
    2018 Tundra Limited CM Premium Package
    Ron, quick question, since the 2-prong on/off switch isn’t lighted, I really don’t need a ground wire going to it, right? Isn’t a ground/3-prong on/off switch design really only necessary if it is lighted?
     
  8. Nov 1, 2018 at 6:39 AM
    #8
    NewImprovedRon

    NewImprovedRon Hey! Get off my grass!

    Joined:
    Jul 8, 2015
    Member:
    #1501
    Messages:
    13,050
    Gender:
    Male
    First Name:
    Ron
    Bentonville, AR
    Vehicle:
    2015 Radiant Red TSS Doublecab 4X4 Off Road
    Deck rail system, Bed divider, door sill protectors, LED reverse light bars, Aries Bull Bar with 28" 180 watt LED light bar, LED step lights, LED bed lights, driver-side grab handle, TRD Rear Sway Bar, BedRug bed mat and tailgate mat, Morimoto Fog Lights, more to come.....
    If the switch isn't lighted, then you can use the 2 pin switch. Just place the switch between the power from the fuse box Add-a-Fuse and the trigger wire going to the relay. I assumed that your switch was lit when in the "on" position. My bad assumption. As info, I used an OEM switch for my light bar that matches the other switches in my dash. It is lighted with an LED light that comes on with the other switches when the headlights are turned on and further lights up another step when the switch is turned on. It is a 4 pin switch with the 4th connector going to the illumination circuit in the dash. Good luck with your project!
     
    Cthulhu [OP] likes this.
  9. Nov 1, 2018 at 7:53 AM
    #9
    Cthulhu

    Cthulhu [OP] Executive Redneck

    Joined:
    Jul 21, 2018
    Member:
    #17251
    Messages:
    795
    Gender:
    Male
    First Name:
    John
    South Carolina
    Vehicle:
    2018 Tundra Limited CM Premium Package
    Thank you kind sir!!
     
    NewImprovedRon likes this.
To Top