Brake and dash lights flash with turn signal

Today I installed a K Suspension headlight wire harness; if you are not familiar with this it is a parallel harness that uses the old headlight plug to trigger a new relay so it pulls power right from the battery for brighter lights. I also replaced all bulbs with LED and swapped to an electronic flasher. After I was done I went to test everything out and the whole Jeep is screwed up. I have swapped to all LEDs on a previous 98' XJ, Toyota trucks and a Subaru Forester without any problems....

Problem
Right turn signal - right side blinks
Left turn signal - right front blinks faint, left rear and all brake lights, the odometer and dash lights flash too.

Start the Jeep and it runs horrible with what seems like small random backfires.

I had a lot of stuff go bad at about the same time, so for the last few days I have
replaced the PS pump and lines that failed
new water pump (sounded like crap) thermostat and hoses
oil filter adapter seals (pissed out a quart of oil last week)
replaced the fuel injectors

So I know I touched a lot of stuff which makes it harder to narrow down, but I don't see how any of this would cause that much grief with the lights. Any ideas?

If I were to troubleshoot this one, assuming the wiring was not damaged or incorrectly connected, I would suspect a bad led bulb. Another possibility is a ground at one of the corners knocked loose or corrosion is preventing good contact. Start unplugging bulbs and test the function. Headlight harness shouldn't have anything to do with the turn signals and brakes. Good luck!

When I swapped injectors to "4 holes" jobs from eBay, my 97 ran like pure excrement. Unless there was something wrong, I'd swap back to stock.

Otherwise, it's really easy to damage the coolant sensor (which is probably very brittle given its location) whenever you do anything with the accessories. Check that.

Turn signals: the electronic flashers you swapped in are my guess.

FYI this is on a 2001 XJ

This morning I tried swapping back to the factory flasher relay. Not enough load I'm guessing and the lights don't flash at all.

Went up to O'Reilly's and bought 4ga cables, replaced grounds (batt/fender, batt/block, block/firewall) and the positives (batt/PC, PC/Alt, batt/starter) no difference. I will spend some more time this evening cleaning all the grounds. Very weird problem, but it must have to do with the grounds.

This is frustrating. I also have the K-Suspension Viper coil swap to install.

Fixed!

The light issue was a single LED reversed. Flipped it and they all worked fine, including the dash.

The engine running bad was a bad coil with the K-Suspension kit. That one took a long time to figure out. Cleaned and sanded ALL the grounds, swapped back to the old injectors, checked all harness connections, put a timing light on it, checked sensors and finally tried the coil, which fixed it.

Just closing out the solution to this thread.