Help requested with 74 rear light leads (2 Viewers)

[Nolescruiser]

Hi everyone,

I have been pouring over the wiring schematics from Coolerman and others, but cannot seem to find one that is an exact match for wire color / directions. Maybe this is because its is a fun transition Sept 1974 FST, or maybe because it is a fun CA factory smog vehicle!

Anyway... the previous, previous owner had wired in a clunky trailer wire harness and I am trying to delete that harness while making everything work as it should.

The attached picture is where I am currently at. I do not have running lights (bulbs and leads have continuity, I have checked the running light grounds), I do not have any lights in the rear (Brake, running, reverse, signal)

Nothing from this harness is connected to either grounded bolts. I assume this is problem #1.

I am trying to figure out:
- what should be grounded?
- Or do individual light housings properly ground everything, and no additional ground is needed at rear cross member?
- judging by factory bullet connectors, did this have a factory trailer harness wired in, or was this just for the rear license plate light?
-Lastly, what wires need to be connected where!?


Here is what I have followed from original wiring diagrams:

GB - Driver Turn signal
GW - brake lights
G - Side marker signal lights , running tail lights , license plate light (which I don't have physically have on the vehicle
GY- Passenger turn signal
GO- Something to trailer socket change over?
RL- Trailer harness wire? Reverse light wiring?

Thanks in advance!

-Nick

 

[rkymtnflyfisher]

A little drawing I did on my rear harness last fall, hopefully you find something useful.

 

[rkymtnflyfisher]

White Black is ground.

 

[rkymtnflyfisher]

FYI, there are a couple of discrepancies in my labeling, I'll try to dig up a revised version.


It's all there in @Coolerman website though.

 

[Nolescruiser]

White Black is ground.

Thanks for all the help! I will look this over while under the cruiser tomorrow.

Do you know if you had a WB wire present splicing out where the lead for your rear license plate light would be (under rear tub in between taillights). I haven’t seen one in the area.

My FST has drop down tailgate if that changes avenue of wiring for the rear plate light compared to others

 

[rkymtnflyfisher]

The WB at my rear light may have been added when I relocated the license plate onto my cooler carrier.

If you are currently working on that rear section now is the time to add a ground wire, it's easy, accessible, and the benefits are huge, even if that ground only goes back to the frame somewhere close.


I'm trying to remember exactly how the taillights are grounded, I forget if there is a wire, or if they're bonded through the housing and screws.

 

[pb4ugo]

My 75 light fixtures were grounded thru the mounting bolts. When i rewired the tail lights I added grounds riveted to the housing and grounded them to the frame. I think later models had grounds incorporated in their wiring, but I don't know when that started.

 

[ToyotaMatt]

Hi everyone,

I have been pouring over the wiring schematics from Coolerman and others, but cannot seem to find one that is an exact match for wire color / directions. Maybe this is because its is a fun transition Sept 1974 FST, or maybe because it is a fun CA factory smog vehicle!

Anyway... the previous, previous owner had wired in a clunky trailer wire harness and I am trying to delete that harness while making everything work as it should.

The attached picture is where I am currently at. I do not have running lights (bulbs and leads have continuity, I have checked the running light grounds), I do not have any lights in the rear (Brake, running, reverse, signal)

View attachment 3580689
Nothing from this harness is connected to either grounded bolts. I assume this is problem #1.

I am trying to figure out:
- what should be grounded?
- Or do individual light housings properly ground everything, and no additional ground is needed at rear cross member?
- judging by factory bullet connectors, did this have a factory trailer harness wired in, or was this just for the rear license plate light?
-Lastly, what wires need to be connected where!?


Here is what I have followed from original wiring diagrams:

GB - Driver Turn signal
GW - brake lights
G - Side marker signal lights , running tail lights , license plate light (which I don't have physically have on the vehicle
GY- Passenger turn signal
GO- Something to trailer socket change over?
RL- Trailer harness wire? Reverse light wiring?

Thanks in advance!

-Nick


View attachment 3580628

are you installing the original 9/74 oem 4 wire square connector plug tail lamps ?

or

a newer style , like the ones with the 6 pin oval connector plugs , that have the added white wire / with black tracer stripe ???


this key point should be talked about by you below , shoe your intended to install tail lamp assy's , then a more detailed and correctly comprehensive approach can be laid out for you ....


my created and Authored a more the comprehensive FJ40 Rear Tail Lamps Connector ID TECH Thread here many years ago , if you start at the first page 1 , and read and study all i go over , and all the other input from many other members too , then i think for certain you Can and WILL be able to ID all your color coded Tracker Striped wires above ....

i am going to make a very important observation here you need to know now , and address too ,.....


i can see that most of your tail lamp curcut wires are all now too short in lenght , this is normal when human hands alter and create the rats nest you are going about now the CORRECT way , know that you are , and i do think your approach is sound too , you do need a 1974 EWD wire diagram here for sure , all the wires are green w/ colored tracer stripes minus the red wire w/ blue tracer strip ....right ?


see my link below , it will absolutely help you here in more ways then you can possibly imagine ...

,

OEM Tail light / Lamp Electrical Connector Differences / Types FJ40 1/75 - 10/ 84 ( 8/26/2019 Final OEM TOYOTA Parts Solution Updates )

OEM Tail Light / Lamp Electrical Connector Differences / Types FJ40 9/73 - 10/ 84 i would like to Dedicate this Thread to my Friend & fellow member @Coolerman :) note: if anyone sees a factual error or has input to add please send me a PM so i can't EDIT any errors with a...

forum.ih8mud.com

,

.

 

[Nolescruiser]

are you installing the original 9/74 oem 4 wire square connector plug tail lamps ?

or

a newer style , like the ones with the 6 pin oval connector plugs , that have the added white wire / with black tracer stripe ???


this key point should be talked about by you below , shoe your intended to install tail lamp assy's , then a more detailed and correctly comprehensive approach can be laid out for you ....


my created and Authored a more the comprehensive FJ40 Rear Tail Lamps Connector ID TECH Thread here many years ago , if you start at the first page 1 , and read and study all i go over , and all the other input from many other members too , then i think for certain you Can and WILL be able to ID all your color coded Tracker Striped wires above ....

i am going to make a very important observation here you need to know now , and address too ,.....


i can see that most of your tail lamp curcut wires are all now too short in lenght , this is normal when human hands alter and create the rats nest you are going about now the CORRECT way , know that you are , and i do think your approach is sound too , you do need a 1974 EWD wire diagram here for sure , all the wires are green w/ colored tracer stripes minus the red wire w/ blue tracer strip ....right ?


see my link below , it will absolutely help you here in more ways then you can possibly imagine ...

,

OEM Tail light / Lamp Electrical Connector Differences / Types FJ40 1/75 - 10/ 84 ( 8/26/2019 Final OEM TOYOTA Parts Solution Updates )

OEM Tail Light / Lamp Electrical Connector Differences / Types FJ40 9/73 - 10/ 84 i would like to Dedicate this Thread to my Friend & fellow member @Coolerman :) note: if anyone sees a factual error or has input to add please send me a PM so i can't EDIT any errors with a...

forum.ih8mud.com

Lot to reply to here, thank you for the detailed response.

Yes, I will be sticking with the original OEM 4 pin style connector plug (unsealed first generation). As the 40 sits, I have both tail light assemblies which are currently grounded through the housing. Minus the tail lamp gaskets, the assemblies are in good shape and the harness / connections leading away from them appear to be unmolested until the direct middle point in-between the two tail lights.

Tomorrow I will either solder or do the 6-32 small bolt modification listed in your linked thread which will provide a solid ground connection from each tail light assembly to the frame.

When you mention my tail lamp circuits are too short, and there is a rats nest, I could not agree more...
Here is a picture of the trailer wiring when I began

I am trying to compare a few copies of wiring diagrams for the 1974 year. I have blown up and laminated a Haynes copy, which has tracked pretty closely, but not always exact to my config.

Still just wanting to figure out which like color wires need to be connected to continue a circuit, and other than the sold green wire (which should go to a license plate lamp) which other wires can be capped off. I guess tomorrow will be a good multimeter day.

-Nick

 

[pb4ugo]

Coolermans website has wiring diagrams for most yrs. He also sells plugs, terminals and proper color coded wires and some sub harnesses. I found a lot of the color codes were the same thru the yrs. The license plate light wires are the same color as the parking lights. I used pop rivets to ground my tail light housing. Fyi.

Cruiser Wiring

 

[ToyotaMatt]

Lot to reply to here, thank you for the detailed response.

Yes, I will be sticking with the original OEM 4 pin style connector plug (unsealed first generation). As the 40 sits, I have both tail light assemblies which are currently grounded through the housing. Minus the tail lamp gaskets, the assemblies are in good shape and the harness / connections leading away from them appear to be unmolested until the direct middle point in-between the two tail lights.

Tomorrow I will either solder or do the 6-32 small bolt modification listed in your linked thread which will provide a solid ground connection from each tail light assembly to the frame.

When you mention my tail lamp circuits are too short, and there is a rats nest, I could not agree more...
Here is a picture of the trailer wiring when I began

View attachment 3581530

I am trying to compare a few copies of wiring diagrams for the 1974 year. I have blown up and laminated a Haynes copy, which has tracked pretty closely, but not always exact to my config.

Still just wanting to figure out which like color wires need to be connected to continue a circuit, and other than the sold green wire (which should go to a license plate lamp) which other wires can be capped off. I guess tomorrow will be a good multimeter day.

-Nick

- ok , sticking with the 4 pin connectors is fine if you follow 2 super simple , but mission critical here step by step points ......

- you must then add the 5th wire white wire w/ black tracer stripe and home run both of them , then spliced together , up the passenger side inner frame rail with all the rear chassis wires circuits .....

- not taking the to make the time to do exactly what me , @ and several other folks and share in my Tail Lamps Connector ID tech thread i share with above is only going to create a short term band aid solution you will have re-visit back there in the sooner then soon near future , and think of it that way too ....


one or both your rear metal tail lamp housings you are now planning " both tail light assemblies which are currently grounded through the housing. " ....

looses its NEG- ground touchy-feely ONLY metal on metal contact you are planning on relying on ? and the car or school bus rear ends your Land Cruiser ....

then you become the at fault then and there ,,,, this is a real thing that can occur if only one lamp housing fails to make NEG- ground contact the years of age time and layers of black oil based enamel

- 2nd topic is the 4 pin connectors , the 1st generation ones in my tech thread are all Smooth both male and female , NO latching / locking tabs , the 2nd generation ones w/ orange gaskets and 2 locking latching tabs on the MALE housing are NLA / Disc . so , then how do you prevent the Cheezy Smooth 1st Gen. ones from vibrating loose and coming apart ? causing the same exact possible scary scenario as the no neg- ground on i explain above ?


Eazy Peezy text book solutions on both mission critical topics here below :

.
- These are the smaller 6.3mm NON-Sealed Updated Locking / Latching Connector Housings TOYOTA eventually integrated with the First Generation 9/73-8/76 Rear FJ40 Tail Lamps
.

 

[ToyotaMatt]

.

This is how to keep your good condition zinc plated current 4 wires ONLY tail lamp housings , yet also make them super reliable and most of Safe long term ...

i have done this several times in the past , when faced with a similar same situation on both a personal land cruiser and also a hand full of Shop Clients ones too , Especially ones just imported from South America , with there Hard Candy Shell paint jobs that make the Ring in Bling for sure ...

- the wiring skills in south America are another story ./.... ...

.

the last 2 below detail how i use a solid copper 1/8 " pop rivets from home depot or lowes , the copper does NOT react with the zinc plating and carbon steel metallurgy , causing dissimilar metal corrosion , kind of a electrolysis like on boats for example ...

use 16ga wire for all your wiring repairs too above , its very very user friendly to work with , and 1 size spec. jump up is thickness of a copper conductor vs the thinner toyota oem wire you have there is not a bad thing in anyway , especially on the new grounding circut white wire w / black tracer stripe ....


upon completing the below , you will in-fact have 2 Fully Polarized Tail lamps , that no longer need to rely on only a chassis-type metal to metal surface contact outdated Fred Flintstone era technology design ....

.
.

.

 

[Nolescruiser]

Thanks again everyone for the inputs.

So I have since removed the tail lights and 4 broken bolt / screw heads later…

There was quite the mess! Look at all the packed sand in the bumper housing!

After cleaning up the tail light assembly housings I have soldered on a ground as other users recommended. These grounds will connect to the chassis.

I will be reinstalling the taillights once new gaskets arrive. I have also taken apart / cleaned up the headlight switch and turn signal switch. Headlight switch was in pretty good shape but all 12 contact points in the blinker switch were completely buried under grime. I’m almost certain this is the first time in 50 years most of these screws have been turned