CaptnAmerca

This one is frustrating. Both tail lights of my wife's 2000 4Runner are not working. First thing I checked was the bulbs. I replaced all 3 pairs of lights in the assembly - brakes, reverse, and tail lights.

When that didn't solve the issue, we looked at the "tail" fuse under the hood. It looked fine, but we replaced it anyway. Tail lights still didn't come on. I checked the other lights that are supposed to be on the same circuit, the lights on the dash, and the license plate light, those all work.

Just to check, I pulled the "tail" fuse while the headlights were on, and the dash lights and the license plate went out, and went back on when the fuse was re-inserted.

I did the same with the tail relay in the same fuse panel under the hood, and had the same results - the dash and license plate lights went out, then came back on when the relay was re-inserted.

The truck has an attachment for a trailer, but we've never used it. I visually inspected it, and it looks perfect, like it's never been used. There are no indications of wear or damage to the wires, or even the harness itself.

The radio is stock, we don't have any aftermarket parts, and haven't had any accidents.

Any ideas on where to start looking next?

fierohink

When was the last time the lights worked properly?

have you done anything since then? Car wash? Detail? Off-road? Get rear-ended?

The simplest way, albeit time consuming and frustrating, is to take a test light and check the light socket, then follow back to the split connection where the left and the right branch apart, then farther back to the next connection and so on until you find voltage.

A light circuit light markers is pretty basic. You have the fixture, the wiring, the switch, the power, and the ground. One of those has to be it. Since it’s both side, I would lean towards the wiring between the switch and the sockets, or a faulty combination switch itself.

The trailer harness, is it a factory Toyota or aftermarket? A factory toward plugs in between the original twilight wiring harness, no splices. An aftermarket one could use scotch-locks and have pinched or broken the original wires.

CaptnAmerca

It's hard to say when the tail lights went out. We only noticed because we had someone follow us home one a few days ago, and they mentioned it. We never go off-roading, and haven't had any collisions. We did go to the car wash last week. That's the only "event" I can think of, and it would have been before we noticed the lights out.

Since it's both lights, it would make sense that the issue is at some point before the wires split off in both directions. At what location do the lights split? By the combination switch, do you mean the selector for the headlights?

I would guess that the trailer harness is factory. It's just too clean-looking. There are no obvious wire splices, or even any scratches on the thing.

I will probably stop at AutoZone and get a test light tonight and see what it will tell me.

Thanks!

CaptnAmerca

Tested one of the tail light sockets with a test light. There was no power coming to it. Will have to trace it backwards when I get time and daylight.

CaptnAmerca

OK, this is resolved, and I'm posting this to hopefully save someone some aggravation in the future, because this was absurdly simple.

It was the wrong type of bulbs in the tail lights. It should have been a dual filament bulb, I installed a single filament.

That's it. That's all it was. If you're searching the forums for help, do yourself a favor, and double-check your new bulbs. Read on only if you want to give me a chance to salvage some dignity.

So, both tail lights being out was weird, but the first thing to check is the bulbs, obviously. I took them out. They looked fine, but I figured it's been a few years, just replace them any way. I go to the local AutoZone, and right away there is a guy at the counter loudly arguing witheveryone behind the counter about how they didn't give him the full refund he was due. In my arms, I have a toddler who wants to touch or grab EVERYTHING. I have the bulb and I'm trying to find a match, but its a lost cause with refund guy dominating the store and trying to keep a live octopus from pulling items off the shelf. I give up and bring the bulb to someone at the counter who looks glad to get out of the refund battle.

I tell her the make and model, give her the bulb, and she looks it up in the computer. We walk over to the shelf, she finds the match and we leave the store with new bulbs. I install them....nothing. Great. So it's not the bulb.

I get on the forums for advice, and pick up a test light from NAPA, check the sockets....no light, so no power. Check the fuse, still good. Check the relay, still good. Inspect the trailer hitch, looks fine. I give up. I just don't have time to get more in-depth. It's dark out by the time I can even start looking at it. Time to take it to our mechanic, who we trust to shoot us straight. It was the wrong bulbs. I feel like a total dumbass on the phone with him, but the whole thing only costs us 25 bucks. The cost in time and ego are aggravating.

Still, I'm wondering how I missed the bulbs. There was the mystery of no power to the sockets. Well, back to the test light. The damn thing doesn't work at all. Broken piece of trash right out of the package. Despite having the old bulbs in her hand, and looking the item up on the computer, AutoZone gave me the wrong bulbs....a brand new test light at NAPA was completely defective, but the real rube was me in trusting these places to have a minimum level of competence in their chosen field of expertise.

Lights on
Lesson learned
Rant over.

75w90mantraN

That was a similar situation for my father-in-law's Chevy. Had installed the wrong rear passenger tail bulb and then he couldn't make any right turn signals from the back. After I checked and replaced it with the correct type, the electrical system was back to normal.

We jump to other possibilities, but hey checking the obvious costs next to nothing!

I dont rely on the sales clerk, except for opinionated discussion.

wyoming9

iTrader: (1)

The thing with places like Auto Zone or any of the like any counter people with any smarts because of having so many stores are fast tracked into management .

I try and use one Napa store and my Toyota dealer

RAD4Runner

Thanks for the update. Glad you figured it out.

Yes and yes^^^

akwheeler

I just goes to show that if you intend to do ANY of your own work on your vehicles you should prepare yourself with a basic set of hand tools, a volt meter (and learn a few things about how to use it), a test light, and some common replacement parts. Fuses, light bulbs, oil, filters, tune up parts and such don't take up a lot of room and don't have a shelf life to worry about. You can get many of these items on line for cheap and not have to worry about the wrong bulb issue if you have a few of each (or a bunch) on hand. I got what is likely a lifetime supply of 10/15/20 amp fuses (bags of 25 I think) all for about $20. The same for marker/tail light/ dash bulbs, never have to wonder or go buy a 2 pack for $6 ever again.
Another thing is testing your test equipment, cords and alligator clips break, test lights fail, so when you use them test your connections first and make sure your light (or meter) will work before you mis-diagnose something. In the electrical trade there is a test sometimes referred to as the "live/dead/live" test where you test your meter on a known energized circuit then test the circuit you want to verify is safe to work on, then test your meter again on the know circuit to verify that you didn't blow up your meter (or a connection came loose) and that you are safe to touch the dead circuit. Working on 12 volt DC wiring won't kill you, but doing similar tests will keep you from following the wrong rabbit hole when performing diagnostics.

wyoming9

iTrader: (1)

I tend to go overboard with extra parts

thefishguy77

iTrader: (1)

I have a buddy that runs a good shop. Any questions at all i ask him the part number. Then I order most of my stuff online. Not a huge fan of the local shop in town and its a 30 mile drive to the next one.