Right Turn Signal Issue

hey guys,

New member just trying to get some help. I’m having an issue with my passenger side turn signals. They don’t work....sort of.

2003 tundra AC with oem hitch system

This issue started 2 days ago after I drove to visit some family. It did rain on the interstate but only for about 20 minutes or so.

When headlights are off, driver side blinker works normally f/r. Passenger side will blink normal in front, but will cause both brake lights to blink as well as the dash and hvac lights that blink at the same time. With parking lights on/headlights on, turn signals do not work at all. Driver side parking light will light up white and passenger side will light up amber (I have switchbacks) and rear passenger will have turn signal light on as well. I’ve done the following:
Unplugged turn signal relay and plugged it back in (aftermarket relay for LED; with no headlights, I can hear the relay click for both l/r)
Unplugged both front bulbs and swapped.
Unplugged both from sockets and swapped.
Unplugged rear turn signal bulb.
Unplugged rear passenger tail light harness.
Unplugged trailer harness.
Unplugged headlight stalk and tested with a known working. No change.
Unplugged hvac controls and hazard (hazard button does the same thing as passenger symptoms; dash lights blink and both brake lights blink)
Unplugged battery.
Checked all fuses under hood and by footwell.
Checked grounds in engine bay.


My only other thought is that it’s a pinched wire or ground on the passenger side. I’ve traced out the harness and there’s no noticeable kinks or melted wrapping or any copper showing. Kind of running out of ideas. No electrical work in about 3 weeks or so. Swapped in new tail lights and harness. Everything was working and no issues. Double din was swapped in 2 years ago and no issue at all. Haven’t towed anything in months.

This literally happens after just driving to visit family. Didn’t hit anything or run anything over.

Really hoping to see if anyone has had the same/similar issue. Any help is appreciated. Thanks.

 

I'm not an expert, but it sounds like it might be a grounding problem to me

 

That’s what I’m guessing. But I just found the part number for the oem trailer harness. Didn’t realize that there’s a black box connector. Gonna go and look for that and see if that’s a problem.

 

There's two ground points for the rear harness. One is at front of the fuel tank and the other is in the left kick panel in the cab.

 

Do you happen to know if the one by the kick panel is within a connector (7-pin, 9-pin, etc) or is it by itself? I’m hoping that it’s the black box from the trailer harness or a ground. But idk where the black box would be mounted. It wasn’t there when I was checking but I wasn’t down there too long.

 

There is a connector but the wiring diagram shows it going to the sheet metal. Should be a white wire with a black tracer.

 

Thanks. I’ll see if I can get under there tonight to check the one by the gas tank. I feel like since there’s a black box/converter for the trailer harness, that could’ve shorted out. But then again, I’m not 100% sure. But I also feel like it could be something small that I’m overlooking.

Side note. Would you be able to provide the diagram? Or pdf? If it’s too much trouble, no worries. Thank you for your replies and your help!

 

I can do the pdfs but it'll be tomorrow. It's a lot easier to do on a desktop.

Trailer converter is actually in the dash, behind the left side of the glove box.

Ground point we talked about earlier is with a gray 12 pin connector.

 

No worries man. I’d really appreciate it. I’ll be taking a look tomorrow in the morning.

I didn’t realize the trailer converter was behind the glove box. Figured if it went bad it would be because of dirt and water. Are these known to go bad like the usual/curt ones?

 

No idea on the failure rate. I'd say they're more hardy than the Curt ones for sure.

 

Gotcha. I figured since it’s in the cabin. But aside from that and the 2 ground points, any other ideas? I’m inclined to say it’s a ground/short, just not sure where.

And thanks again for your help!

 

Failing a ground issue next best guess would be the switch.

If you have a helper and length of wire, I'd test the resistance of the wire from the light socket to the ground point to see if it's a wire issue.

 

Here's the PDF, hopefully I got the all the pages.

 

Thanks man!

Just a quick update. I was able to unplug the gray connector and issue was still there. Haven’t gotten around to the converter or checking the grounds yet. Really hoping that one of those is the issue. Really baffled as to why it just randomly happened. Unless it’s just super old and finally gave out.

 

So I checked the converter. Unplugged it and issue still exists. Unplugged the signal relay again and arrow still shows up on dash.

The ground by the fuel tank. Is that on top, inside or? I looked at the pdf and couldn’t really tell.

 

I honestly don't know, FSM says front surround so I would assume either on one of the mounting bolts or bolted directly to the front of it.

You could try tapping the white/black wire at the taillights and grounding it to a bumper bolt to see if that solves the issue short term until you can track them all down.

 

Would that solve the issue in having temporarily? So tested the voltage at the tail lights. The blinkers were getting anywhere from 28.x to low as 1.x. Inspected the bulbs and none of the bulbs were broken. I’m literally at a wall right now (aside from grounded the tail light itself) and I couldn’t find the ground around the fuel tank. Least I couldn’t see anything mounted. Another thought was maybe the cluster ground was bad but then my cluster wouldn’t light up, which it does. I did notice wiring from the front passenger side fender. Didn’t get to fully trace it out but I’m wondering if there’s a ground there that maybe got punched or melted. Issue is only on passenger side.

 

If the issue is coming from the rear lights it should be a good temporary fix

 

I can’t say for certain if it’s front or rear. Only thing for sure is passenger side. With the rear turn signal unplugged. Same symptoms (dash lights blink and both brake lights) and same thing with passenger front turn signal. Since I have switchbacks, soon as I turn the parking lights on and bulb is plugged in front, it automatically turns amber.

 

So still having the issue.

If I ground the light, would I just have to ground the rear (white/black) or the ground from the actual harness? Cause I haven’t been able to pinpoint if it’s the rear or front or both. Should I try grounding the front one as wel?

 

Just at each light, if you're not sure try one and then move to the next if the problem still exists.

 

Alright. I’ll give that a try. But just out of curiosity, even when there’s no bulb in the socket on passenger side, same thing happens which inclines me to believe that it is indeed a short somewhere. When parking lights/headlights are on, hazards don’t work. I’m stumped and it’s getting to a point where it’s frustrating, only cause I like to use the turn signals lol. But I’ll see what happens when I ground the lights.

Also, does the brake light, turn signal and reverse lights all feed into one ground into the harness? I know they each have an individual ground but wasn’t sure if they were spliced together somewhere down the line.

 

I cannot base this on your truck but i have seen near the same conditions on Mercedes. It was caused by one of a few things.
1. The customer installed brand X bulbs. These would fit the socket but pulled to much or to little amps.
2. The customer or one of the hacks I worked with put the wrong bulb in the socket. The bulb fits but only has one center contact instead of two. this joins both contacts in the socket.
3. all the bulbs are correct but the filament inside one bulb has broke at the end and fallen down on the other filament and welded both filaments together. This is real hard to see. look real close at all bulbs, especially the ones that are erratic.

By the way, didn't you say something about led modification? Try putting it back to factory for a test. Just plug in factory and unplug aftermarket.

also when you swap bulbs around and if one has joined inside, you are still putting the defective bulb back in. that and it will light up in both turn, brake and running light positions even though it is defective. there were times I had to replace all the bulbs in the car, than start putting the old bulbs back in one at a time in order to find 1 or 2 bulbs with this defect.

Note: if you pull the wrong bulb out and go get a new one matched to the bulb you pulled out, you re-install the wrong bulb again. Most common is the bulb is one or two contacts. look at the bottom of the bulb and in the socket, make sure they match

 

see above

 

Thanks for your reply.

I swapped bulbs from driver to passenger and vice versa. And same symptoms. Even with no turn signal bulbs plugged in, the passenger indicator still lights up on dash. When inspecting the bulbs, there’s no corrosion on the ends or broken filaments of any kind. Everything was working fine until my most recent long drive. I’m suspecting a ground/short due to regardless if there’s a bulb in either socket or not, the issue is still there. Grounding the turn signals would be my next move as I’ve literally done everything else.

 

Welcome from Northeast Connecticut. You have a ground problem and it's back feeding through your other lights

 

Yeah that’s what I’m thinking. So if I ground the front and rear turn signals, sure hope that fixes the problem. Unless it’s a ground that’s in the middle of the chassis.

 

Well. Grounding the rear turn signal didn’t change anything. Suppose I have to go and trace out every wire. Ugh.