How To Looking for rear light wiring help, 1974 40 series

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Toby755

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Hello,

I have a 1974 wiring harness powering my 1973 lights, frame is 1970. I have the 1973 round style tail lights. Wires to the rear are Green, Green/Blk, Green/Yellow Green/Wht and Red/purple for reverse. The harness has a green orange in there but no power to it. Green black goes to left rear turn signal, Green Yellow to right and Green White to brakes. Green Goes to side markers and license plate. There is a Green/Wht bullet connector coming from the turn signal that is not plugged into anything.

Problem is that I have no running lights when the headlights are on.

Brake lights work well
Turn signals work well
Hazards work well

Any ideas about how I can get some running lights? Do I need to run a jumper wire perhaps?
 
With a Heinz 57 you need to get a tester - one of those light bulb probes works well. Be sure all the bulbs/fuses are good and the sockets are clean inside. Clean and inspect all the connections in plugs. Plus make sure the fixture is grounded.
What there are like 8 running lights to track down. I'd start with the 74 wiring diagram. Wasn't there a big change in that time area ig switch and stuff. A simple jumper might be the ticket, or swapping pins in a plug. Its 50 year wire, could be a break inside that doesn't show threw the insulation. I would strongly consider adding a new hot wire and a ground to each light and connect it up to the correct wire from the light switch so you have running with the switch on. Your connection to that switch could be bad, or the switch itself. I have rebuilt most of my switch over the last 40 years.

Maybe some free manuals or Coolermans wiring can help

Land Cruiser Factory Service Manuals (FSMs)

Factory service manuals (FSMs) for your Toyota Land Cruiser ! From the 1950s to the present!
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Toby755 said:
Hello,

I have a 1974 wiring harness powering my 1973 lights, frame is 1970. I have the 1973 round style tail lights. Wires to the rear are Green, Green/Blk, Green/Yellow Green/Wht and Red/purple for reverse. The harness has a green orange in there but no power to it. Green black goes to left rear turn signal, Green Yellow to right and Green White to brakes. Green Goes to side markers and license plate. There is a Green/Wht bullet connector coming from the turn signal that is not plugged into anything.

Problem is that I have no running lights when the headlights are on.

Brake lights work well
Turn signals work well
Hazards work well

Any ideas about how I can get some running lights? Do I need to run a jumper wire perhaps?
Click to expand...
The quick answer is a jumper wire from the running light to the tail lights. All the running lights should be on the same circuit. The problem your going to have is the 73 round tail light is a combination light. It has one 1157 light bulb which has 2 filaments in it. One filament/wire for the running lights and the other brighter filament is for brake and turn light which only has 1 wire to operate it. The 74 tail lights has a separate amber turn light and a combination brake and running light with the 1157 light bulb. 1 filament/wire for running light and the other brighter filament for the brake only. This setup adds an additional wire, which the round light doesn't use. You say both your turn and brake light works. Are they the same brightness, as they should be? Will the turn signal work with the brakes on? The 74 harness should have, 1 wire for running, 1 wire for brakes, 1 left turn, 1 right turn(side dependant) and 1 for reverse. The 73 would have 1 wire for running lights and 1 wire for brake/turn and probably 1 for ground wire. The turn signal switch at the column turns off the brake light power and then supplies power to the directional turn light.
 
Yes brightness is OK, brake lights work with the blinkers on, just no source of continuous power for the running lights. I have an old 3 wire set of trailer lights that I will mock up or maybe I'll try a jumper. Thank you all, I may have to run a 74 light setup and do some fabrication. Hate to cut into a good rear cross member and I love the look of the round lights.
 
Another alternative is to get a trailer light converter. It converts separate turns and brake lights like the 74 to combination lights like the 73 has.
 
Oh that's a good idea! I'll look around for one much appreciated! Tractor supply he's em' headed there for deer corn anyway! (Its a Pa thing)
 
Living in the Past said:
Do the tail light work on the first pull of the light switch? Do you have round tail lights with a single bulb? When you have one of the turn signal on and apply the brake does just the other light while the other flashes.
Click to expand...
I have round lights with single bulb, double filament brand new from Cruiser Corps. Tail lights do not work with first pull of light switch unless Green wires are plugged in. Should the Green/Blk and Green/Yellow have continuous power or just the green? There are only 2 wires going to this light. Yes when the turn signal is on and the brakes are applied I get both a flash and a light on the other side light.
 
What turn signal switch are you using, 73 or 74? With the turn signal on when brake is applied does the one flashing go out between flashes or is there brake light on both sides. Wondering if the wire not being used on turn signal switch is the wire for the wire for brake pedal switch. Instead of the wire from the brake pedal switch instead is hooked up to the wire for the tail light. If that is the case the brake light will be dimmer than the turn signal. Normally on the round dual element bulb. With the brake applied when the turn signal is on the light flashes on and off completely. Only the tail light is dimmer. If this is the case the suggestion of the trailer converted will fit the issue. What needs to happen the brake signal from the switch has to go to the trailer light converter and wire it hooked to has to go the right location in the light switch.

No guarantee but it also may be as simple as figuring out wire of the brake switch on brake pedal doesn't have have 12 volts on the time and hook it up to the loose wire on the turn signal switch if from a 73. Apply the brakes and see if both lights come bright. With turn signal on that one should flash on and off. If that works then wire going to the back you disconnected needs to go to the light switch. Probably an unused wire.

I do not memorize with colours. I go by the what the wires are suppose to do.
 
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Living in the Past said:
What turn signal switch are you using, 73 or 74? With the turn signal on when brake is applied does the one flashing go out between flashes or is there brake light on both sides. Wondering if the wire not being used on turn signal switch is the wire for the wire for brake pedal switch. Instead of the wire from the brake pedal switch instead is hooked up to the wire for the tail light. If that is the case the brake light will be dimmer than the turn signal. Normally on the round dual element bulb. With the brake applied when the turn signal is on the light flashes on and off completely. Only the tail light is dimmer. If this is the case the suggestion of the trailer converted will fit the issue. What needs to happen the brake signal from the switch has to go to the trailer light converter and wire it hooked to has to go the right location in the light switch.

No guarantee but it also may be as simple as figuring out wire of the brake switch on brake pedal doesn't have have 12 volts on the time and hook it up to the loose wire on the turn signal switch if from a 73. Apply the brakes and see if both lights come bright. With turn signal on that one should flash on and off. If that works then wire going to the back you disconnected needs to go to the light switch. Probably an unused wire.

I do not memorize with colours. I go by the what the wires are suppose to do.
Click to expand...
Thank you! Great information.
 
Toby755 said:
Hello,

I have a 1974 wiring harness powering my 1973 lights, frame is 1970. I have the 1973 round style tail lights. Wires to the rear are Green, Green/Blk, Green/Yellow Green/Wht and Red/purple for reverse. The harness has a green orange in there but no power to it. Green black goes to left rear turn signal, Green Yellow to right and Green White to brakes. Green Goes to side markers and license plate. There is a Green/Wht bullet connector coming from the turn signal that is not plugged into anything.

Problem is that I have no running lights when the headlights are on.

Brake lights work well
Turn signals work well
Hazards work well

Any ideas about how I can get some running lights? Do I need to run a jumper wire perhaps?
Click to expand...
Do you have running lights to the front directionals and front side marker lights? If not, your issue is with the supply to those circuits. The running lights should be powered directly from the headlight switch, and have no connection to the brake/turn signal lights.

My 73FJ40 wiring harness had the extra wire for the 74+ three light rear combination lamps, but the "extra" circuit to separate brake signal from turn signal was not used.
 
I’m getting 12v to the green all the way in the rear. When I plug the green in to the 2 function light, it lights up. When I plug the green white into the green white light on the light then step on the brakes I have brake lights but I don’t have blinkers. Unplug the green and plug in the black green on the left I have blinkers and brakes, but no running lights. So I have power to all three of the wires that I’m supposed to have power to just only two out of three functions at the light. Confusing, I know. Maybe with his harness and blinker switch I am compelled to use a newer light fixture.
 
Indications of bad grounds. The ground path is lamp to steel bracket, steel bracket to rear cross member, to the side rail, to the OEM connection of the negative battery cable to the frame under the bolt holding the brake line junction block the frame. I'd start by cleaning up TBE lamp to bracket and bracket to rear cross member.
 
73FJ40 said:
Indications of bad grounds. The ground path is lamp to steel bracket, steel bracket to rear cross member, to the side rail, to the OEM connection of the negative battery cable to the frame under the bolt holding the brake line junction block the frame. I'd start by cleaning up TBE lamp to bracket and bracket to rear cross member.
Click to expand...
It's always a ground isn't it? This is a frame off resto so everything is brand new. I will clean the grounds again and will run a separate ground wire from the light to the frame rail. Really appreciate all of the great feedback here!
 
Toby755 said:
I’m getting 12v to the green all the way in the rear. When I plug the green in to the 2 function light, it lights up. When I plug the green white into the green white light on the light then step on the brakes I have brake lights but I don’t have blinkers. Unplug the green and plug in the black green on the left I have blinkers and brakes, but no running lights. So I have power to all three of the wires that I’m supposed to have power to just only two out of three functions at the light. Confusing, I know. Maybe with his harness and blinker switch I am compelled to use a newer light fixture.
Click to expand...

Its not likely a ground issue. I took a deep dive into converting later model tail lights with a separate turn light to early combination tail lights back in the 90's. I looked at adapting a 73 Fj40 or fj55 turn signal switch into the later model column to get them to work. I found the combination brake/turn switch has the brake light circuit going to column and thru the switch. When the turn light is activated the switch turns off the brake light power for that side and supplies power for the turn light, left or right. In the 74 and later model wiring harness doesn't have the brake light circuit going to the column or thru turn switch, so adapting the earlier combination switch becomes really difficult. I decided not do that. In later harness the brake light circuit is a completely separate circuit from the turn circuit. As i mentioned in post #3, the 74 and later lights with the separate turn has one wire going to the amber light and has 2 wires going to the red lights. This bulb is a dual filament bulb(1157 bulb). The dim filament is for the running light and the bright filament is for the brake light. The early style combination tail light uses the same type dual filament 1157 bulb. 1 dim filament for running and 1 for brake/turn. So with later harness you'll have 1 extra wire. I'd hook up your running light wire to the dim running light filament and that circuit is done. Now you have to deal with the 2 remaining harness wires with only one wire on the taillight. One for turn and the other for brake. Now you have choices, just hook up the brake circuit and then use hand signals for turning, add an extra light on each side for a turn or brake light or get a trailer converter. I think if you wire both the harnesses brake and turn lights to the one tail light wire you will get either a turn signal or brake light but not both. With the turn light flashing and you depress the brake you are feeding power up the turn light circuit wires and the lights do weird things or vice versa.
 
pb4ugo said:
Its not likely a ground issue. I took a deep dive into converting later model tail lights with a separate turn light to early combination tail lights back in the 90's. I looked at adapting a 73 Fj40 or fj55 turn signal switch into the later model column to get them to work. I found the combination brake/turn switch has the brake light circuit going to column and thru the switch. When the turn light is activated the switch turns off the brake light power for that side and supplies power for the turn light, left or right. In the 74 and later model wiring harness doesn't have the brake light circuit going to the column or thru turn switch, so adapting the earlier combination switch becomes really difficult. I decided not do that. In later harness the brake light circuit is a completely separate circuit from the turn circuit. As i mentioned in post #3, the 74 and later lights with the separate turn has one wire going to the amber light and has 2 wires going to the red lights. This bulb is a dual filament bulb(1157 bulb). The dim filament is for the running light and the bright filament is for the brake light. The early style combination tail light uses the same type dual filament 1157 bulb. 1 dim filament for running and 1 for brake/turn. So with later harness you'll have 1 extra wire. I'd hook up your running light wire to the dim running light filament and that circuit is done. Now you have to deal with the 2 remaining harness wires with only one wire on the taillight. One for turn and the other for brake. Now you have choices, just hook up the brake circuit and then use hand signals for turning, add an extra light on each side for a turn or brake light or get a trailer converter. I think if you wire both the harnesses brake and turn lights to the one tail light wire you will get either a turn signal or brake light but not both. With the turn light flashing and you depress the brake you are feeding power up the turn light circuit wires and the lights do weird things or vice versa.
Click to expand...
BAM!!! There it is, thank you! Been beating my head against a wall for a week now! I'll just modify the rear cross member for newer lights and be done with it. Thank God I didn't cut the tub for the reverse light! Anybody want some brand new round turn signal lights, brackets and a reverse light from Cruiser Corps on a fire sale....lol
 
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