Wire identification help

Preface: I have used the search function & could not find anything covering what I am about to ask. Maybe it's in here somewhere, burried under the 874 identical threads asking about how to wire a 3rd brake light. Anyway...

This morning, I got in my truck & noticed I couldn't shift out of park & my turn signals weren't working. I checked the fuses & noticed the 'turn' & 'stop' fuses were blown. Replaced them, & they blew out instantly...over & over. So I went to the tail lights, as I've had issues with the 'tail' [light] fuse blowing in the past & had been meaning to investigate further, & noticed that there were FOUR different 4 pin trailer wiring harnesses wired up simultaneously, & two of them were melting. In a fit of mild fury, I cut them all out just to do away with the redundancy of hack jobs. In doing so, I cut two wires that turned out to be part of the factory harness...oops. Now I'm trying to figure out what they do. For context of the picture, this is the loom that runs parallel to the rear bumper, in between the bumper and spare tire. It's fairly centered, but slightly closer to the drivers side. Any idea what these wires are for?

 

You find the other end of it? Just crimp em back together again and call it a day.

 

The other end was spliced into a melted 4 pin trailer harness. Considered the lights weren't working before I started messing with it & melted harnesses are never something you want to add to a vehicle, I don't think trying to reverse what I've done & return to my starting point would be a great idea.

 

I see a white/black and a solid green. Is that correct?

 

Yep, that is correct. Based on the limited wiring diagrams I've been able to dig up, I'm thinking the green might be power & white/black ground for the stop light circuit? Unfortunately I don't have my test light or multimeter with me to confirm this--I'm a mechanic by trade (admittedly handicapped with electrical work) & need my truck working to get the shop where all my electrical tools are, so it's a difficult situation trying to identify what wires belong to what circuits & what all is factory wiring vs spliced in by a previous owner.

 

I have the whole FSM collection at home, I’ll help you later.

 

You're the man, thank you!!

 

This is from the "Tail light and Illumination" (license lamp) page of the 2003 FSM. Look top LH and you'll find the green, coming off the 10amp tail fuse. Look lower center and you'll see the W/B as a ground.

Not sure if this gives you what you need, but for what it's worth.

 

Green is the tail lights and and white black strip is a ground.When it rolled off the line.

Though since your harness is a mess no telling what those wires might be connected to at this time

 

Figured out part of why the wiring was so confusing to trace...looks like someone took some soldering/splicing liberties when installing a plug & play trailer wiring kit After pulling out the extra wiring, it's starting to look more like a simple tail light harness. That said, if anyone has the full wiring diagram with the stop light & turn signal diagrams, that would be extraordinarily helpful. The one posted helped a lot, but unfortunately it looks like Toyota split the schematics into 4 sections: one for the stop light circuit, the tail light circuit, the backup light circuit, & the turn signal circuit

What I've gathered so far is that the last owner spliced the ground for the trailer harness into the main harness side of the driver side oem wiring, so I cut that bird s#!+ solder out and was left with a white wire with a thin black line & a white wire with a thick black line that need to be reconnected to their counterparts with a butt connector. Simple enough. The passenger side has two green wires that are cut right down to the base of the connector on the vehicle side of the circuit (as opposed to the taillight side, to clarify), so I'll need to figure out where those use to go. Honestly at this point I think I'm going to need to call the dealer & see if they sell the entire connector assembly with the pins & some color-correct lengths of wire attached so I can get this thing back to oem, but hopefully I can limp it by until then.

First image below is where the trailer ground wire (yellow) was soldered into the drivers vehicle-side ground circuit. The second is where the two green wires (which feed into a single pin on the connector) were cut on the passengers side light. Also an extra length of wire was added to the hot wire for the stop light for some reason.

 

Apologies for double posting, but as soon as I read through my last post and looked at the second picture it became pretty clear that the two green wires connected to the random length of red wire that was added are supposed to connect to the stubby lengths of green wire on the connector. I have no earthly idea why someone would do that, but power is getting where it needs to go so for now I'll leave that alone & call the passenger side good.

 

It may not help in your particular situation, but splitting the wiring diagram into separate circuits is way better. Usually someone has a problem with a single circuit and trying to read through pages and pages of wires that include multiple circuits is difficult.

In comparision a wiring diagram for a 2001 Dodge van involved going through about 4 non-consecutive pages to trace a single circuit from battery to fuses to sensor/bulbs to ground--very difficult to follow the wires.

Good luck with your problem.

 

I can see how it might help for a lot of situations, I'm just used to seeing wiring schematics set up as one schematic for one pigtail. I've also found it helpful for diagnostics as the circuits within a single pigtail tend to be somewhat interrelated (as in this case where 4 different circuits share various hot wires & grounds at the tail light assembly). In an ideal world, the manufacturer would provide both to account for the variety of reasons why someone might need a wiring schematic, but all you can do is work with what you have. It'll get figured out one way or another.

 

More progress...

I can only speculate as to what motivated all this, but it turns out the last owner presumably had a problem with corrosion or maybe loose connection on the pigtail, so instead of cutting the pigtail out and replacing it or reconnecting wires with butt connectors, he spliced a new wire into each existing wire both before and after the pigtail, effectively bypassing the pigtail itself. I'm at a loss for words, I've only been doing this stuff for a few years but this is the greatest electrical blunder I've seen. In the pictures, anywhere you see tape or the solder itself is a bird poo solder with a new wire added to bypass the pigtail. The following pictures are what was left after I cut it all out. I left a few solders together to help me figure out which wires connected to what, since there are a few wires that are the same color (multiple solid greens).

 

Another update: decided to go ahead and replace the drivers tail light assembly since a lot of those wires are down to stubs & I just don't feel like looking at a nest of butt connectors anymore. Waiting on the auto parts store to grab it from their local DC & give me a call. The pigtails appear to be okay on the harness side, so I'll try & clean the corrosion up & bend the female flat blade connectors back in for a nice solid connection, but if I have any issues with it I've confirmed that my local Toyota dealer has a pigtail in stock for each side. Oh & the mysterious wires sticking out of the loom by the bumper are for one of the tag lights, which has been flopping around in need of replacement for a few months so I'll leave that until I can get the truck back to work with the luxury of a lift & all my tools handy.

The only remaining mystery is two sets of matching wires on the harness side of the drivers pigtail: two identical solid green wires and two identical red/black wires. The matching wires both splice into the same pin on the pigtail which I think narrows it down. I suspect one of the greens may trace back to the green wire for the tag light, or possibly over to the passenger tail light, but I'm unsure about the red/black wire at the moment. I know from a wiring diagram I found on another post from this forum that they're part of the backup light circuit, but I don't know if it matters if the wires are reconnected one way or the other. My guess is that one splits off to the passenger backup light & the fact that they're spliced into the same pin on the pigtail means it doesn't matter which end connects to which, but honestly it's stuff like this where my lack of electrical knowledge becomes apparent, I just don't know until I test it with trial & error. Good thing I bought lots of fuses.

 

Got the wiring fixed up and the new taillight in, works like a charm. The driver side tail light/brake light female pin on the pigtail was bent upward to where the male pin wouldn't be able to slide in, so I bent it back down, scuffed all of the pins with a pick tool, & applied some dielectric grease to protect it. Drivers side is back to 100%.

The passenger tail & brake lights still aren't getting power, but after taking a closer look at the pigtail, I noticed the green wires had been cut & spliced back in after the pigtail because the pin was totally missing for that circuit, probably rotted out a long time ago. Gonna do it right and get the harness side pigtail replacement & also get a new passenger tail light assembly since that's the only way to get that end of the pigtail, but for now I'm satisfied with having everything but the passenger tail & brake lights working. Appreciate all the help, & to try & help anyone who might find this thread down the road, I'm gonna include a fairly simple brake down of the wiring for the tail lights.

So the way the lights are wired is everything goes from the fuse box to the driver side tail light pigtail, & from there almost everything has 2 wires spliced into each pin on the harness side of the pigtail: one that comes from the fuse box to provide the power, & another to carry that power over to the passenger tail light assembly & tag lights. This is why the driver side has several more wires than the passenger side. If your tail light has brown, red, & yellow wires on any of the pigtails, it has an aftermarket trailer wiring kit installed. Everything except the ground wire should be plug & play on these kits, assuming/hoping that nothing else like what I just dealt with exists on this planet. This means that you can get rid of it by removing the pigtails with the red/yellow/brown wires, remove the ground from whatever it's bolted to, & pull it all out. Toyota only uses green with various colored stripes, white with black stripe, & red with black stripe wires on the tail light pigtails. Anything else is not oem.

And here are some pictures of the completed driver side & messed up pigtail on the passenger side.

 

Just curious where you live how bad the tail lights sockets are rusted ?

 

I live in SLC, Utah & the truck has been here since 2010, but spent it's first 6 years in Vermont (according to the Carfax). I bought it a year ago because it was stupidly cheap ($3000 with 180k miles, got it for the trade in value at a used dealer where I used to work) & the frame had been replaced under warranty at some point after it came out here from the east coast. So the frame, suspension, steering, etc are all exceptionally clean for the year, but the body still shows the east coast roots, & even out here the dry air only goes so far if you don't clean the salt off your truck at least once a week during winter.

 

Looks like you got it all figured out!