I have an '04 Tacoma, so when my lights are on my left turn signal stays on, but doesn't blink jut stays on constantly, and when my lights are off and i turn my left blinker on all the lights on my dash and radio console blink in time w/ the turn signal. The right turn signal has no issues. Anyone know what might cause this?? Im pretty sure it's the turn signal switch. If so is it worth trying to do myself and have to deal w/ the Airbag bypass BS or just taking it to the dealership and have them mess w/ it. The new switch is $110.00. Is there a way to trouble shoot and determine if it is the switch and not a short before Get it fixed or buy the part and fix it myself?? Any help would be great.

 

It sounds like you lost the ground on the left side. The lights are grounding through the turn signal circut or you have a short through 2 of the wires.

 

get a supply of spare bulbs and replace one at a time. It could be as simple as a dual filament bulb that is shorting out the other functions.

Other than that it could be the towing converter black box, but check bulbs first...

 

i have a 2002 Tacoma with the exact same problem. there is a trailer harness installed that i did not instal myself. i am tracking grounds but don't see any burnt out wires or melted stuff. i have checked the bulbs they look fine. can a dual filament bulb short on the inside where i cant see it? even if it looks OK and not burnt? also if i just start throwing in extra grounds do you think that would work?

 

I have a similar problem with my 98 Tacoma. The left blinker light on dash stays on at all times when key is turned on When I use that blinker my rear lights both blink well the top half of them the bottom don't do anything, ever. The right side blinker works fine except that the rear bulb was out so I replaced it, it still doesnt work. The other thing is when I have left blinker on it blinks inside as long as I don't have my foot on the brake pedal then it just stays on steady,also if I am not using L blinker and I put my foot on brake regardless if key is on or not, the front left blinker lights up like a brake light. WEIRD!!

 

It still sounds like a ground issue. If the alarm has a 4way flash option, and most do, you may have either pulled out a wire or caused one to short. Go over the harness with a fine tooth comb. Push, pull and wiggle each wire (not too much force, ie; dont pull the wire out. if you did, that was the loose wire.) while the turn signal is to the left or till the left flasher on the dash goes out. Then repair that wire...

 

Just had this happen on my T100. The trailer harness was fubar and once I unhooked it and put everything back to stock no more issues. New trailer harness worked fine.

Before I figured it out I changed all the bulbs, disconnected stuff, thought it was the signal stalk, blinker relay, etc.

Just unplug the trailer harness points in the rear taillights and put it back to stock and see what happens.