Solution: Tail fuse keeps blowing

Hello all! I was recently working on my 2nd gen Tacoma and I was troubleshooting an electrical problem. I probably spent way too much time fixing it so I wanted to share what I found.

TL;DR: Check for lose or stripped wires inside your tail lights.

The problem:
1. Climate control illumination lights were not working. This was the first thing I noticed because I was going to adjust the climate control at night and couldn’t see the dials. I thought the bulb inside the unit was bad (this wasn’t the case) so I didn’t think much of it.
2. My nighttime tail lights, license plate lights, fog lights, and PS brake light stopped turning on. This I first noticed when a good Samaritan pulled up next to me and told me that she couldn’t see my taillights. (This is why I like living in the country).
3. The tail fuse located in the interior fuse box (this is located behind the pop-out tray to the left of the steering wheel) was blown.

The hunt:
1. First I tried a new fuse, but it blew as soon as I turned my lights on. I checked both sides of the leads with an ohmmeter hooked to ground. One side was open line, the other side was about 2-3 ohms to GND. Thus, I knew I was dealing with a short circuit.
2. I tried disconnecting my fog lights. I have aftermarket lights so I thought there was a chance they went bad. This was not the problem and did not change anything.
3. I removed my stereo and climate control units. I also have an aftermarket radio system and I was worried that one of the wires behind the unit was shorted. I also thought that there was a chance the climate control unit was bad since it was not illuminating. This also was thankfully not the issue. Everything looked normal and I was able to reassemble the unit after the problem was found.

The solution:
The next thing I tried was removing the tail light units. This was pretty simple to do since there were just two 10mm bolts for each taillight on the inside of the truck bed (check your owners manual for more details). After a few clips later, the tail lights popped right out. The first thing I noticed is that the inside of the lights were extremely dirty. I felt is was necessary to clean out the dirt so i could better inspect the wiring. The next thing I noticed was that the DS tail light had an extra set of wires compared to the PS tail light. I wasn’t sure what this was at first, but then I remembered that my truck had a camper shell on it when I first got it. I since removed the shell since I’m not a big fan of them. However, that shell likely had an additional brake light on the top. The wire that was left over inside the DS tail light was likely the wire that powered that light. I also noticed that the wire has some of the insulation stripped off on the hot wire. I removed this extra pair of wires and reconnected the tail lights. After installing a new fuse, everything worked! I just needed to clean up the mess I made lol.

Lessons learned:
1. Don’t be lazy when removing components from your truck. When I removed the camper, I didn’t want to open my tail light to remove the extra wire. This cost me several hours of my time over 5 years after the fact. Something like this easily could have cost me several hundred dollars at a shop.
2. Don’t give up looking for the problem. The issue will always be the last place you look and I about threw in the towel. Keep on going and you can probably find it yourself!
3. If a fuse says ‘tail’ check the tail lights first. I assumed that all of the symptoms were causing the issue because I had worked on them previously. Sometimes this may be causing the problem but don’t automatically assume you messed up that portion of the mod/repair. Had I just checked the tail lights first I would have saved a lot of time.

I hope you found this thread enjoyable. Thanks for reading! If you have any questions, feel free to reply. I’m not a mechanic and this is my first post so I may not be able to help you but I’m sure someone here probably can. Have a great day!

 

Thanks for sharing and welcome to TW.

 

Nice write up benmehart. Unbeknownst to me, my tail lights apparently haven't been working for quite some time, and I've never been pulled over by the law, nor did anyone mention it to me. I had an earlier problem with my VCS (???) indicator coming on and had my brake pedal switch replaced along with a fuse. The mechanic asked if I'd towed anything recently, or changed anything, but I had not. The VCS light warning disappeared however the climate control illumination was nil which I didn't notice until I did some night time driving. I blew it off as a faulty LED in the circuit board that may have blown out when the original fuse failed. Just hadn't gotten around to researching that problem. I'd seen other posts mentioning the trailer harness, so that seemed the easiest to eliminate. Popped in a new fuse and everything worked...climate control illumination and tail lights. Will purchase new trailer harness soon.

 

Yeah us big city folk are an odd bunch. I see people with tail light problems often, sometimes I can get next to them and holler out my window. The reaction is varied from thanks to my face is in the phone and I’m ignoring everything else, no habla, a look like I know and don’t care, a look like f you stay there while I get my hands on my gun to shoot at you.

 

Thanks for sharing. Lot of dikheads ask questions and want answers then never post again and don’t share their findings. Good on you for being upstanding and glad you fixed your light issue

 

Hey, I’ve been dealing with this issue for the past week. I finally found tgat the issue was my turn/drl bulb. I put auxbeam WJD 3157 bulbs in place of my factory bulbs and they were causing the fuse to blow

 

Just for fun trivia, Chevy back in 1950s and some ford models to0. they would wire the tail light bulbs in series with the dash backlighting so if a bulb burnout and went open circuit, your dashboard lights would be out. no idiot codes back them, it was a simple effective way of knowing you had a tail light out.

and.... most cops knew this so if you got pulled over and tried to play stupid, he would ask you to turn on your lights and point out that your dash lights for your speedometer and or other gauges were not illuminated....they would frown at you for acting like you didnt know. its dark and you cant see your speedometer ??? yeah, cant play stupid there.

sometimes the left tail light was in series with the tachometer dash lamp and the right one in series with the speedometer dash lamp, that way if a single bulb failed, it didnt take out both tail lights. so, depending on which gauge was not backlit, you would know which side bulb was out

oh i love the simplicity of yester-year before some things got over engineered