One drl not coming on

So I did the 18-19 Trd Pro headlights swap on my 2016 SR5 and I have everything working but can’t get one of the drls to come on. I used a v3 harness. Anybody know what could be the problem?

 

If the harness was working before, it should still be OK. If this is the first time you've used the harness, then maybe your harness connections are bad, or the harness is bad.

Use a multi-meter to measure voltage at the DRL connector...no voltage, then start working backwards to find where continuity is lost. If you have voltage at the connector, then use the ohmmeter range to test the two bulb elements for continuity, or eyeball it to see if the bulb is good.

Edit: @Coflo143 If "I used a V3 harness" means that you used a VLED v3 LED for DRL and it has a pigtail and y-connector w/resistor, AND you find you have voltage at the truck harness, then the problem is in the VLED wiring. You can trouble-shoot it or assume the LED is bad.

 

The led isnt bad the lights are two months old came off my truck. I wanna say a ground issue or possibly loose wire in harness somewhere. The harness i purchased because it had the dim feature. Never any issues and i originally started with the 2018 limited led lights then switched when i had pro lights. I feel its a ground issue though.

 

That's more info than I had from the OP. Since you supplied the LEDs and are familiar with the installed configuration, the OP could use your help locating and trouble-shooting the grounding points.

Not being familiar with the grounds on the stock harness, my thought is that a bad ground on the truck harness would affect both sides, not just the one side. Unless, of course, the truck harness requires grounds on both sides, and one ground is loose, and that ground was previously loose and not observed by the OP. If the VLED wiring has it's own grounds, no other grounds should have been disturbed.

I would first check for bad connections in the reinstalled VLED wiring, primarily to insure the LED is getting power.

 

Yes the harness i sent with the lights has two different ground locations, d/s and pass/s. I spoke with op so he is gonna recheck wiring.