2020 Tacoma SR5 rough idle after LED headlight install

Purchased and installed Alpha Rex Nova headlights into my sr5 tacoma. Headlights are functioning properly, however after reconnecting the battery the truck was really struggling to idle and would stall when I pushed on the throttle.

I'm pretty sure it's the ECU struggling to adjust to the new headlight power draw and I've read where after 50 miles or so of driving the ECU will "relearn" everything, but I can't even get the truck out of the driveway without it stalling out. Any ideas?

 

I would put the stock headlights back in and see it corrects itself.

 

Unhook the battery for five minutes and try.

 

I have tried that a few times (5-30min intervals) but no luck yet unfortunately.

 

Well then you're going to have to put the old headlights back in.

 

Dumb question but did you use an adapter with your wiring harness? Seems like it isn't made for the lower power draw

Edited because it definitely isn't the ECU after some research.

 

Sorry, but none of this makes any sense at all. The ECU doesn't need to learn how to power lights, and lights have nothing to do with engine control. Something else happened during the install. Check all your fuses.

 

Since it’s the SR5 I didn’t use an adapter with the wiring harness. Plug and play, red to pos. black to neg. and fuse tapped INJ

 

Haha yeah that’s what I thought when it first happened, makes no sense. I’ll recheck the fuses and keep ya’ll updated. Appreciate the replies!

 

There’s your problem. You fuse tapped the injector fuse. Make sure the fuse didn’t blow

 

Aye-yup! I think what's happening is you're pulling the injector signal to ground and 'fooling' the ECU. If this is 'plug & play' why did you need to tap in to another circuit?

 

Pretty sure you need to fuse tap for the running lights on non-TRD models

 

Did the instructions say to tap the INJ circuit? Holy cow, what a terrible idea.

 

If it has DRL's (not familiar with these lights) you're definitely going to need an adapter because the SR5 doesn't have the correct wiring for it.

As others have said you tapped a line that shouldn't have been spliced into.

 

It’s not the first person that’s done it, I’m pretty sure I saw another thread a few days ago about having to tap the injector fuse

 

I think OP was either misled or didn't do his research. There is no plug and play headlight assembly for SR5's that has a DRL. You have to make use of a wiring harness.
Even if the instructions told you to tap the INJ circuit that's not a great idea. As you have seen its throwing off your timing because the ECU is undervolted.

Easiest way to troubleshoot would be to just cut/unplug the tap from the headlights and see how it runs. If that fixes the problem than you know it was the root cause. If that doesn't fix it just solder the wire back together.

Or just keep shooting down suggestions and enjoy the 35k brick sitting in your driveway. Everyone here is trying to help you. ¯\_(ツ)_/¯

 

fuse is still good. Instructions on alpha rex website say to fuse tap INJ since the sr5 doesn't have LED drls

 

Well it sounds like Alpha Rex had their head up their ass if that's the instructions to tap the injection fuse. ECUs don't like under volt conditions and in some cases it will mess them up

 

Yeah, I got curious and checked out their instructions. They definitely say to fuse tap INJ.

First, I'd disconnect that fuse tap and see if that fixes the problem.

 

Most tap the radio fuse in the cab under the dash for the drl in an sr5.