mud-dog27

Ok ive searched but all im finding is wiring up to a switch or adding a switch to the existing working circuit.

Ok so i recently picked up an '86 toyota truck 4x4 and as it would seem with almost any used modified vehicle the previous owner was a complete moron when it came to wiring, because its a flat deck he had ghetto fabbed some tinted dodge ram tail lights on there so ive managed to get blinkers, running lights and brakes all up and running with some tasteful universal truck lights but unfortunately the reverse light wiring is unsavable.

Now my question, I realise i could just bypass factory and run them to a switch and call it a day but as much as i love switches i would rather run it through the factory reverse switch that is in the trans. I was thinking just run a basic switched relay curcuit as one would do with fog lights. Has anyone done so? Any pointers would be great before i dive in.

wyoming9

iTrader: (1)

First make sure you have a good switch or go buy a new one .

Why not run off the Engine fuse like factory.

Has the wiring been hacked even for the reverse lights.

All you need is a power supply run through the ignition switch fused then to the reverse light switch.( you don`t want to leave it in reverse and come back to a dead battery)

then to your reverse lights .

If you want to run it through a relay you can but you really don`t have to.

justin_4runner

why not just follow the harness farther up the truck tell u find good wires for the reverse lights and just tap off that wire and run it from there? also if u have power to the switch on the trans then all u need to do is tap off that switch and run it back to the lights and ground lights.

waskillywabbit

iTrader: (-1)

Factory wiring diagrams are in the FSM
www.ncttora.com/fsm

:wabbit2:

mud-dog27

this guy completely hacked the harness or else i would just fix the factory harness all i have is the splitter part of the harness that also goes to the 4WD light switch but due to it hanging under there it made contact with the exhaust a few times so it was melted, given the lack of normal body rust or frame rust for that matter that us canadian normal see on toyotas i have a feeling this truck was at some point a 2WD auto as it has a sticker on the firewall for an auto trans service.

vital22re

iTrader: (2)

I ran some 10 guage wire to a universal socket for power in my bed. I wired in a relay from that power source to run my aux reverse lights. I just used the factory switch to power the relay.

Hadmatt54

Okay!
Where exactly is the harness hacked up?
Is everything under the the passengers kick and under the passengers seat intact?
Here is the routing of your backup lights on an 86:-
Power (Red Wire) comes from the 15a engine fuse located above the drivers side kick. This runs through the dash harness over to the passengers side through connector N1 pin #14 (20 pin connector) if the truck originally was an auto or connector N3 pin #9 (10 pin connector) if the truck originally was a manual. This connector ties the circuit to the engine harness and it goes through the firewall through the back of the engine harness to the transmission back up light switch. From the switch a red/Blue wire returns through the engine harness & firewall to connector N1 pin #5 (directly above pin #14) if auto or connector N3 pin #2 if manual. From there a small harness containing all of the wiring for the rear of the vehicle including fuel guage and pump runs under the passenger seat where the red/blue wire makes a connection to the rear harness in connector Q1 pin #8. That harness goes through the floor and follows the frame to the rear of the truck. Q1 pin #3 is the ground (white/black wire) that comes from the right front fender to the rear of the vehicle.

So that's your circuit, it's not a complicated one by any means and it can't be all hacked up, so get an volt /ohm meter start tracing it out and see what exactly you are up against.

As far as the section that is all melted.. some wiring of the same colour from a junked Toyota, a soldering iron, some connectors and heat shrink will easily fix that up. If the backup light switch and wiring and connectors are completely destroyed..once again your local junk yard is the perfect source for repair parts!

mud-dog27

Thanks hadmatt ill give that stuff a look, i know for the most part the harness on the passenger side is there, as i had to bypass the plug that is under the seat to get the brake lights to work and there is another wire thats bypassed as well, not sure what its for though, as i said the splitter is pretty melted plugs and all so ill likely run my own connectors. Would you be able to tell me where that splitter ran to? i know there are some plugs on the passenger side of the engine bay but the plugs on the splitter were melted beyond recognition so they could be for that but not sure. In the end if i could set it back up through factory wiring that would be my preferred method as im only running factory bulbs so the circuit wont be overloaded.

Hadmatt54

What exactly are you refering to with the term "splitter"?

mud-dog27

bout a 3 foot section of harness with plugs on either end, one plug fit the 4wd light switch and the other kind of fit the reverse light switch but again aged plastic plus heat means i get to rewire stuff.

To give you another idea of this guys electrical skill he relocated the gas tank to the rear of the frame so he had to extend the harness and simply twisted the wires together wrapped in tape and called it good...im still trying to figure out if the fuel gauge reads FULL all the time due to the relocation or the crappy wiring but i think this weekend im going to by pass that harness plug under the passenger seat just because as ive mentioned its already go to wires bypassed and its a nasty looking plug so ill just eliminate it as an issue.

Hadmatt54

All of those connectors can be easily changed with junk yard parts. Every wire in the connector has a release that lets you pull the wire metal connector out of the plastic one. I made 2 tools to do this, one was a piece of brazing rod that I ground down to a tiny flat blade, the other was a jewellers screwdriver that I ground down as well. I have spliced through on harnesses as well, but I try to keep them stock for the most part, especially with this connector. If you ever have to lift the cab off for any reason this connector makes the job a lot easier.

mud-dog27

Ha junkyard toyotas......i wish.

anyway do you have a link or something to these different toyota plugs cause im bound to start wreckin stuff soon seeing as from what ive seen so far these damn things are not labeled.....unlike my jeep where plugs were labeled and weather proof. I could have sworn i saw a list somewhere of the different plugs but cant for the life of me find it now.

mud-dog27

I have found a 2wire plug tucked up under the intake that has a Red/Blue wire so ill run some jumpers and hope i can pull something from a wrecker if i can find a yota in there

mud-dog27

mud-dog27

Lovely job the guy did when extending the harness for the fuel tank relocation.....im hoping that corroded piss poor solder job is the source of my non reading fuel gauge, however it could just be the slight angle change of the tank, as for the reverse light grounds im thinking i may be able to remove those as the lights im using ground through the mounts of the lights



again thanks hadmatt im going to try and locate some OEM plugs for the section of harness that im missing and hopefully the lights should work as i cant see any other major faults in the harness at this point

mud-dog27

Found some more awesome electrical work about 8" beyond this for the sending unit, and surprise the dumbass crossed the wires for the sender.......signal wire to ground......ground to gas light.......gas light to signal wire

Hadmatt54

From the picture that you have of the plugs, the top section is the back-up lights with a red wire on the left and red/blue on the right. With the key on red should be 12v. to ground and a continuity check on the red/blue from this connector to the rear of the truck should tell you if the rest of the circuit is intact. The lower connector is older style 4wd. light 2 wires on it. Does your 4wd switch have 2 wires or does it ground through the switch? The reason I ask this is my 86 has the newer style connector (round with a single wire) and the switch has a single wire, the circuit ground is through the case.

Yeah...if buddy thought he could solder....he should think again!

On the crossed wires...You probably have this all figured out, but Yellow/Red is the sending unit feed to the gauge, yellow/blue is the low fuel light and of course white/black is ground. For the fuel pump blue is 12v + and white/black is ground.
As far as the joint that you have circled with a question mark...that is a factory joint that is usually covered in electrical tape and it looks corroded pretty bad. What I do with these when I do harness work is to clean them up really good and put lots of flux on them and solder them solid, then I know for sure they will not fail.

mud-dog27

Well happy to say i was able to find the small section of harness that i needed with plugs and after fixing a few more wonderful solder jobs i now have functioning reverse lights

As for the the pump/sending unit, i got some schematics and figured it out and soldered it up correctly and finished it of with heat shrink.......unfortunately the gauge still doesnt register, except now instead of it being pinned at FULL, it just sits at EMPTY regardless of how full the tank is. As i mentioned the guy altered the mounting angle of the tank when he relocated it but even still i would think that it would at least give give an inaccurate reading. I'll see if i can do resistance checks on the sending unit or possibly the cluster as i Know the OIL PRESSURE gauge is erratic but ive been told the sending units for those are iffy as well.

Anyway thanks again.