Posting Here Cause of "Wiring Schematics" Description-Tail Light Fuse Popping

[Hurricane721]

Just picked up a 93 Mighty Max (love this damn truck) and the #12 (tail) fuse pops. I can have the truck off, running lights off, put the fuse in, fuse doesn't pop, truck still off and when I try the running lights it pops. Sometimes I can put the fuse in, turn the running lights on and it doesn't pop, but when I turn the truck on the fuse pops after 5-10 seconds. I've checked the taillight bulbs and license plate bulbs, the cables from the taillights and licence plate light to the first junction on the passenger side behind the rear tire, all good, disconnected that junction, put new fuse, fuse still pops. Checked the cables from that junction to the next junction under the passenger seat, disconnected that, put new fuse fuse still pops. The wires go from under the passenger seat across the middle of the floor of the can so I guess next thing I could do when I have time is remove the seats and the carpeting to follow where the wires go from there. Wondering if there is there anything else to check before i do that? I've looked online and can't find a diagram for the lighting system. I'm not sure if there is a relay between the fuse box and the tail lights or where it may be located, I don't know where the ground is for the lighting system (I'm a YouTube mechanic and there'sno videos on this 😂), any help on where these may be located or what else I can do before I start tearing the interior up would be appreciated.

[Hurricane721]

After finding the haynes manual on here with the lighting diagram I found what I needed. Admin can delete this

[Hurricane721]

Bought a new dash illumination switch, when it came, I realized the one in my Max is literally connected to itself. Makes sense because when I got the truck the knob didn't do anything for the dash. The dash lighting and the taillights worked for one day and stopped.


Directly next to the dash knob there's two cables connected to each other, a blank and a black oranges, they look to be for the dtrl/turn signal/wiper switch.


First question is are these supposed to be connected to each other? They have the same male female crimp connectors as the dash knob switch and they're literally right next to each other. Looking at the wiring diagrams I can't make sense or not make sense of it, help on that would be appreciated.


The taillight/license plate lighting cables come up into the cab under the passenger seat and go across the floor and come out up in the corner to the left of the brake pedal.


There are two splits on the green white cable that look like they may be factory but I'm honestly just not sure. Pictures attached of those splices. One of the green white wires was cooked and was connected to other cables after following it from behind the fuse box to where the taillight wires fish out from behind the brake pedal.


My question is if somebody can confirm these are correct or incorrect? They did have crimps on them but one of the cables was decimated and that the dash knob wasn't connected to anything is making me question it was right.


There are three relays on the driver side attached to the body next to the battery, the one directly next to the battery is MD128752, after looking this relay up all I can find is that it is a "multi purpose relay", can anybody please let me know what relay this is for? It seems to be connected to the wiring that is used for the headlights but it's wrapped in so much tape thought it might be easier for somebody to just tell me if I even have to worry about that relay.


There are two other relays between the battery and the cab which also seem to be coming through on the same tape rope coming through the firewall, both of these relays are labeled "056700-4810", thereo cheap on Amazon, just wondering if somebody could also let me know what these relays control.


Just want my taillights to work, don't care if the dash lighting to come on but if my taillights worked I could at least cruise at night haha. Thank you.

[geezer101]

The big relay next to the battery 'should' be the ignition bypass relay. It cuts power to accessories and lights when you crank the engine over to prevent an electrical system overload. It has a 6 wire socket plugged into it. Your wiring pics are a worry. Some look like they've either been crushed or melted from a short. Mitsubishi used little crimped metal sleeves to branch wiring off the same circuits and wrapped them in electrical tape. You'll find them all over the place (mostly main ignition power feeds and lighting circuits)

[Hurricane721]

I appreciate it geezer, bought the relay to double check, should be here next Tuesday. Also bought the dtrl/turn signal/wiper switch to swap out to see if that was the problem. Will update.

The wire that was cooked was melted into other wires, very little and sporadically but still, you think I should also recable those lines or just electrical tape around the parts that got melted together because of the short and call it a day? Feel like it's a dumb question but still. Thanks again.

[geezer101]

I'd cut and strip the damaged area, slide some heat shrink tube over the long end, solder the wire back and shrink it up. If the wire itself has been damaged, you run a risk of it eventually failing if you don't ensure a good connection.

[xboxrox]

Mark at Cruiser Wiring helped me with new fusible links ~ he gave me great service ~ it just so happens that he specialzes in Toyota FJ40 and the wiring parts are same thing Mitsubishi used in our trucks (at least the fusible link connections are same) send Mark an email he can help ~
http://www.globalsoftware-inc.com/coolerman/fj40/wiringmainframe.htm

[Hurricane721]

Thanks, yeah that's what I figured, no reason to risk having problems down the line.

Hell yeah Xbox, looks like he's on vacation, and I hope the harnesses aren't the problem but looks like a great option if I ended up having to go that route.

[xboxrox]

Thanks, yeah that's what I figured, no reason to risk having problems down the line.

Hell yeah Xbox, looks like he's on vacation, and I hope the harnesses aren't the problem but looks like a great option if I ended up having to go that route.
The few times I emailed him there was once he was gone a good while ~ he is worth knowing & worth doing business with him is great if he says YES ~ you might have to send photos or an old piece to him to ensure he knows exactly what you have 'n need ~ I am grateful he fixed me up with factory type fusible links