1974 fj40 taillight wiring help (1 Viewer)

[yayo]

im trying to rebuild my taillight harness ive looked through all the wiring schematics but cant seem to figure out the tail light harness for the driver and passenger side

does anyone have picures of the stock harness plugs ?

for the passenger side i have red /blue (reverse), green/white (brake), green/yellow (signal), green(park)

driver side red/blue (Reverse), green/white (brake), green/orange (turn), green (brake)

when i put it in reverse, the reverse lights signal i have the blue red wire and the red blue wire hooked up to the reverse switch

 

[yayo]

From wiring harness near reverse switch

 

[yayo]

Are these factory connections

 

[Solace in Solitude]

Sorry, mine's a '78... I can't be sure just how closely the connectors match.

IIRC bullet connectors are used at the reverse light switch.

The red tape is NOT OEM... Someone has taped up the wires... Hopefully without crossing any... e.g. Same colors on both sides of the red tape... Perhaps as a result of a partial harness meltdown...

@Coolerman sells a lot of connectors, fusible links, etc. Cruiser Wiring

He also has '74 wiring schematics here Coolerman's Electrical Schematics and FSM File Retrieval

Find your year... Unfortunately, I'm colorblind and can't read the colors on the last two '74 jpg files.

For '78, the rear harness attaches to the main harness, using (IIRC) a 6-pin and a 3-pin connector, at the firewall, on the passenger side. Colors are:
White-black. Ground
Green. Tail and marker lights
Blue-red. Backup lights
Red-black or blue. Stop lights
Green-yellow. Right turn
Green-orange. Left turn

I think that's all...

HTH

 

[LifeinReverse]

Did you get this figured out? I rebuilt my 74 whole light harness connections last sunday. I remember that I had issues with whoever had spliced the rear markers to the harness just did a crappy job. I'm not happy with the connectors I bought as I had to cut the harnesses off both sides to get them to work. Remember that the solid green was hooked to the brake light on both sides (I had to do a splice and run it to the side markers too). Red/Blue - Reverse, Green - Brake(running lights), Green white - Brake (activated), Green Red or Yellow - passenger side turn (I'm pretty sure...I can look if you need me to),Green yellow driver's side turn. I believe the Green Orange is only used if you have a trailer socket hooked up. In the middle of the harness between the two lights I had wires for the harness available but I tapped them up and tucked them away. I also bought the plastic cabling cover for wire harness to clean it up a bit. But who know if that helps. After about 3 hours of working on this...it was a great sigh of relieve to have all signals working. If you can pull out the light fixtures it makes it a whole lot easier. I couldn't get my passenger side off due to a rusted bolt. So I had to squeeze through that small hole to make my connections.

 

[yayo]

@LifeinReverse
I havent had time to really work on it so far i have i have Green - Brake(running lights), Green white - Brake (activated)
signal works when it is in reverse, but both left and right but the reverse light signals

if anything could you see what color wires are plugged in at the reverse switch under the chassis the switch itself has 2 red wire
the wring harness has a blk/ylw, blue/red, red ,red/blue

 

[yayo]

so turns out the rear harness was hacked even further up to lengthen wires for the aux tank

left right
rl rl reverse
g g tail
gw gw brake
gb gy No signals in rear (reverse lights flash)

so my symptoms are

according to all the diagrams you are suppose to wire the rear side markers and licence light to the green but if i do that they dont stay on and turn on when brake is applied

it works fine if i wire it to the gw wire


hazards only work when reverse is engaged and flashes the reverse lights

with ignition on position left signal flashes but both reverse lights flash

right signal does not flash front just gets brighter

I have removed the fuse block and freshed up the connections

ive tried grounding housings directly to the neg terminal of the battery

all new bulbs

disassembled hazard switch and cleaned

tried new fuses

gb wire has constant 12v



at a loss on what to do next ?!

 

[LifeinReverse]

It sounds like, since the harness was toyed with you should assume somewhere along the lines the previous owner crossed the wires.

Take a look at your wiring diagram and pull your hazard switch and back up switch. If the wiring is correct there I would then trace the harness from there to your front lights. Then trace along your passenger side frame looking for anywhere someone tampered with the wires. Then check your passenger rear lights then your tow then your drivers rear lights.

The fact that you press the brake and your lights get brighter and that your hazards flash when you engage your left turn signal really says the the switches are working properly and the lights work ...it's just your wires are not matching your wiring diagram.

And it's probably due to the wires not correct from po's install.

I would definitely start where the harness was lengthened.

Also...don't worry about the right signal not flashing. I say this because I had the same problem with my right rear not flashing. It wasn't until all the wires were correctly connected and my ground has a good connection did my signal work. I also had to take the bulb out and clean the connection. But also, the bulb had to be turned in a certain way if I remember correctly. Because (the experts can shine more light here) the turn switches are heat based causing the circuit to open and close.do when my rear light wasn't working - the front yellow turn light would just go bright and stay bright when I engaged my turn signal.

Oddly, once I corrected all the wires, it took a couple times before the turn signal wouldtblink/engage.

Good thing these are computer controled!

 

[Coolerman]

You have SEVERAL crossed wires. Your next move is to remove the rear harness entirely so you can work on it.
Does this 1974 have the three way tail lights with separate turn light?
Do you also have the seat belt buzzer and the 4th gear indicator for the emissions computer?

Lay the harness out on the floor or a sheet of plywood.
Un-tape it from one end to the other so you can see what wire is connected to what.
Here is how it should be connected for the basic lights:
Green: This is the park/tail lights wire. It starts at the connector on the firewall, runs back to the rear where there are splices that send it to each marker light, each tail light and the license light
Green/Yellow (GY): Right turn. This starts at the firewall connector and goes ONLY to the right turn signal bulb
Green/Black (GB): Left Turn. This starts at the firewall connector and goes ONLY to the left turn signal bulb.
Green/White (GW): Brake. This starts at the firewall connector and goes to the BOTH left and right brake signal bulb.
Blue/Red (LR): Reverse lights. This is the +12V for the reverse lights. It starts at the firewall connector, goes to a female bullet connector near the reverse light switch wires. Plug this into one of the two Red/Blue wires coming from the reverse light switch.
Red/Blue (RL): This wire starts as a female bullet connector. It is next to the LR wire above in the harness. Plug this into the other RL wire from the reverse light switch. It goes back to each reverse light bulb.
White/Black (WB): Ground. It goes from a large ring terminal to the gas tank sending unit ground and if equipped the 2 pin connector for the seat belt switch.

I can build you a new rear harness if you don't want to mess with this.
Send me a PM if interested.

 

[LifeinReverse]

^^^ and that was the expert I was referring to!

Gotta love this community.

 

[yayo]

Does this 1974 have the three way tail lights with separate turn light? yes
Do you also have the seat belt buzzer and the 4th gear indicator for the emissions computer? no seatbelt buzzer no 4th gear indicator


will try pulling the rear harness and fiddling with it wish me luck

 

[yayo]

Success !!!

So I went to remove the rear harness disconnected the front connections and this is what I found

so i sanded the connections added some dielectric grease and plugged it back and shazam everything worked with my reconstructed rear wiring harness !!!!


BIG THANK YOU TO @Coolerman and everyone that chimed in !!!!

 

[bishop1981]

You have SEVERAL crossed wires. Your next move is to remove the rear harness entirely so you can work on it.
Does this 1974 have the three way tail lights with separate turn light?
Do you also have the seat belt buzzer and the 4th gear indicator for the emissions computer?

Lay the harness out on the floor or a sheet of plywood.
Un-tape it from one end to the other so you can see what wire is connected to what.
Here is how it should be connected for the basic lights:
Green: This is the park/tail lights wire. It starts at the connector on the firewall, runs back to the rear where there are splices that send it to each marker light, each tail light and the license light
Green/Yellow (GY): Right turn. This starts at the firewall connector and goes ONLY to the right turn signal bulb
Green/Black (GB): Left Turn. This starts at the firewall connector and goes ONLY to the left turn signal bulb.
Green/White (GW): Brake. This starts at the firewall connector and goes to the BOTH left and right brake signal bulb.
Blue/Red (LR): Reverse lights. This is the +12V for the reverse lights. It starts at the firewall connector, goes to a female bullet connector near the reverse light switch wires. Plug this into one of the two Red/Blue wires coming from the reverse light switch.
Red/Blue (RL): This wire starts as a female bullet connector. It is next to the LR wire above in the harness. Plug this into the other RL wire from the reverse light switch. It goes back to each reverse light bulb.
White/Black (WB): Ground. It goes from a large ring terminal to the gas tank sending unit ground and if equipped the 2 pin connector for the seat belt switch.

I can build you a new rear harness if you don't want to mess with this.
Send me a PM if interested.

How much would you charge for a new rear harness for a1975