High Beam Wire Size

if you want to control the lights any time without needing the high beams on, I would recommend tapping an ignition source, then run that through your switch and the switch to pin 86 on the relay. Ground pin 86. That will give you full control of the light bar anytime you turn the switch on when the truck is on and running.

 

Add-a-Fuse in the engine fuse box on one of the highbeam fuses will do the same thing without cutting or splicing. Use it to trigger the relay. Put a switch inline and you’ve got it made.

 

The Dimmer relay is same part number as the Inverter*(80 amps) and a few others that handle a higher load. You could wire/tap into pin 3 and add a fuse then to your light bar. Run the ground wire of the added light bar to a cab switch for OFF when necessary.
*Part Number: 9008087024
ACC; BATTERY CHARGE; CIRCUIT OPENING; CIRCUIT OPENING (FOR EFI); COOLING FAN; COOLING FAN, NO. 2; DEFOGGER; ELECTRONIC FUEL INJECTION MAIN, NO. 3; FOG LAMP; HEADLAMP; HEADLAMP DIMMER; HEATER; HEATER, NO. 1; IGCT; IGNITION CONTROL; IGNITION, NO. 1; IGNITION, NO. 4; INVERTER; OIL PUMP; PTC HEATER; RUNNING LIGHT; SUB BATTERY; SUSPENSION CONTROL; TOWING TAIL; WATER PUMP; WINDSHIELD WASHER; WINDSHIELD WIPER.

 

None of those relays are capable of 80 amps. Not sure where you are getting that from.

 

If you're not sure why the post?

Same part number for relay...2005 ~ 2018...

 

That relay is only rated around 30 amps. And the inverter itself isn’t going to draw 80 amps or put out that much

 

Well I’m having trouble getting mine to work properly. It was super easy on my second gen. When I connect everything according to the schematic I posted above, everything works except it comes on with low beams and not high beams. Can I not tap into the harness just before the bulb for the trigger? I’m wondering if the relay is wonky for some reason. I used the relay that came with the light bar harness and rewired a harness to follow the schematic. Aren’t all 4 pin relays the same? No matter what configuration I used, it will not illuminate with the high switch. Any insight or advice would be greatly appreciated. I’m working on a 2018 sport DCSB 6 MT.

 

Actually this is the wiring diagram I’m currently using. The schematic in my previous post came with the switch I used in my 2nd gen.

 

Where are you tapped to for pin 86?

 

I used an H11 extension so I wouldn’t have to cut into any factory wiring. I used my meter and checked for 12v at the high beam bulb connector while moving the selector, and tapped the side that didn’t show voltage. That schematic shows “earth” for the connection. But even swapping that connection in my case didn’t allow the bar to light up with the high beams. It either works while low beams are on and high beams are off, or it’s on constant. I’m perplexed.

 

So you have pin 86 on the ground? I use an "add a circuit" and pull from the factory fuse box, the high beam fuse since pin 86 needs a +12v source to trigger the relay.

 

This whole thing has me confused. I considered hitting autozone for a fresh relay and just start over with the harness just because the way this relay acts makes no sense to me. I have some fuse taps so I’ll look for the high beam fuse and see if that does it. I seem to think I had to get a relay from the parts store for this project in my ‘13 but I just can’t remember. Thanks a lot for the help Randy.

 

Not a problem. That's the issue with premade wiring harness sometimes and why I prefer to make my own. Can get the wire length perfect and I know it'll work when I fire it up. Hope it gets resolved.

 

To test your wiring, just momentarily take 12v positive to Pin 86 on your relay. It doesn’t take much amperage to trigger the relay, so it can be any size wire to test it. If it works, you just need to figure out why you don’t have 12v pos coming from the high beams.

 

Ugh I did actually mess that up and ordered an H11 extension and filed the tab on it to fit the wiring. This “simple” project has me feeling rather dumb. Here are a couple questions for you guys.

1. I assume the incorrect extension would not affect this as it’s two wires connecting two wires. Am I correct?

2. The schematic calls for using the -12v earth for the high beam. When using a volt meter this would be the wire that shows zero voltage no matter where the high beam selector is positioned, correct?

3. The switch lights up properly when in use and I’ve quadruple checked the connections there. Would the opposite action that I’m getting possibly be because I have a “normally closed” relay when I should be using a normally “open relay” or vise versa?

Again thank you guys a lot for the help. I plan to get a relay from autozone and try this again ASAP because I question the relay that came with the harness as it had multiple connections to each pin. I didn’t have anywhere near this much trouble with the same project on my ‘13.

 

Most relays have a diagram on the side of them that shows the wiring and if it’s normally open.
I haven’t done this project on the Tacoma yet, but on several older cars. Are the Tacoma headlights controlled on the neg side? Meaning they always have pos and get the ground to turn them on?

 

I’m pretty sure the high beam is ground interrupted. My second gen was for sure, but that also had low and high beam on the same bulb. I wonder if that makes a difference on my ‘18.

 

Here’s the relay that came with the light bar harness. I guess that diagram means it’s normally open? It definitely works in that I can hear a click and power feeds through it. It’s just not doing what it’s supposed to. I may run by autozone and compare with another 40amp relay.

 

Edit: looking at the schematic and the relay, that should work properly. Headlight wire makes connection with AOB switch to magnetize the coil in the relay, closing the switch in the relay to feed 12v from battery to light bar.

That leads me to believe my fault is somewhere on my high beam wire.

I need to research how to test this relay.

 

In your current wiring configuration which trigger feed is to ground (it can be either 85 or 86)?

Connect the other to pos and the relay should energize (click!) and power up the light.

I’m guessing that you don’t have the pos feed from the headlight high beam.