Dim Left Rear Taillight/Blinker

[4joggin]

1972 FJ40- So I have a dim left taillight/blinker. Right side is bright and works well.

New Tailightails both sides.

I have run a long ground from the ground bullit connector directly to the negative terminal of the battery. No luck. Then I hooked up the ground built connect to where is suppose to be at the back of the truck and then used the long wire to connect to the power side of the taillight directly to the battery and it’s brighter.

Also on the left light, with the taillights(marker lights/parking) on and the blinker on, only the one filament lights up and blinks. The right side taillight the marker filament stays on and the directional filament blinks.

I really don’t want to open up the harness to try and find a crush/ poor power wire. Should I just run a new wire and splice it in just before the connector on the firewall?

Is this the connector I’m looking for the the rear lights/blinkers?

Thanks
Steve

 

[4joggin]

All the functions work on the light. Just dim.

 

[charliemeyer007]

Your wires are 50 years old - a new wire is likely the easy way out. I think the blinker filament is the only one that blinks and is the running light, the brake filament is brakes only. I think my blinker connector is under the dash. Its early and I'm sick - sorry

They went to a lot of work to provide color coded wires and a diagram. You should consult the manual. free downloads

Land Cruiser Factory Service Manuals (FSMs)

Factory service manuals (FSMs) for your Toyota Land Cruiser ! From the 1950s to the present!

www.cruisercult.com

 

[4joggin]

Your wires are 50 years old - a new wire is likely the easy way out. I think the blinker filament is the only one that blinks and is the running light, the brake filament is brakes only. I think my blinker connector is under the dash. Its early and I'm sick - sorry

They went to a lot of work to provide color coded wires and a diagram. You should consult the manual. free downloads

Land Cruiser Factory Service Manuals (FSMs)

Factory service manuals (FSMs) for your Toyota Land Cruiser ! From the 1950s to the present!

www.cruisercult.com

Thanks for the references.

My right taillight/blinker. One filament with parking light on lights up when I turn the parking lights on, when I switch the directional to turn right the other filament lights up. Also on the right taillight when the parking lights are NOT on, both filaments are blinking with the right directional on. This is not the case for the left directional only one dim filament is on/blinks.

 

[peesalot]

It could be anything from contact inside the bulb socket, corrosion at any butt splice or terminal at fuse, fuse contact, ground contact, contact in headlight switch & the power for it, hint, start here. It was mentioned that old wires can be suspect, I have found that at any butt splice or crimp, will corrode and turn greenish, the same thing happens down the length of wire you cant see. Happens worse in humid climate, I am in Cali and it happens, takes 20 years but happens.

 

[rainingagain]

Sounds like the right side is functioning as normal for parking and turn signal. What happens when you step on the brakes? Both filaments should light up on both sides.

So you put the ground back as it should be from factory. Then ran a new hot wire from the positive terminal to the hot wire on the back taillight housing and it lit up bright? If so, sounds like you have a fault in the jumper hot wire going from the passenger side to the drivers. Do you have a multimeter? Check hot voltage on both sides. Should be close to 12 but you likely have much less on the left. Check the connections along that leg. Doesn't sound like a ground but they are always suspect - check those while you are there.

 

[rainingagain]

Are the bulbs new? When you say new taillights, do you mean bulbs or the whole housing?

 

[4joggin]

Are the bulbs new? When you say new taillights, do you mean bulbs or the whole housing?

All new, taillights which came with bulbs. I did switch the taillights from left to right and back. Which ever one was in the left/driverside was dim. It was like this with the old taillights as well.

I should mention that with the vehicle in acc just to run directionals. The left side is much slower to blink than the right side.

So you’re saying I should open up the wiring harnesses from driverside to passengers side and look for the damaged wire? When you say jumper…this doesn’t mean the left directional/power wire is “jumped “ off of the right one correct? That would mean that both taillights would blink if the right directional was on? Should the left power/directional/taillight have its own wire from the relay?

When I step on the brakes both light light up. Left is dimmer tho

I’ll check voltage when I get home from work. I started this project way too late last night. Haha

 

[pb4ugo]

Are the frt marker and turn lights the same brightness? What is the voltage at the left rear socket? Did wiggle the bulbs in the socket with the lights on or tried a different bulb? I believe the bulb should be an 1157. You mention you ran a long ground from the bullet connector to the batt. It sounds like a ground issue because both the marker and turn are effected. Did you try bypassing the bullet connector and going straight to the fixture housing?

 

[rainingagain]

All new, taillights which came with bulbs. I did switch the taillights from left to right and back. Which ever one was in the left/driverside was dim. It was like this with the old taillights as well.

I should mention that with the vehicle in acc just to run directionals. The left side is much slower to blink than the right side.

So you’re saying I should open up the wiring harnesses from driverside to passengers side and look for the damaged wire? When you say jumper…this doesn’t mean the left directional/power wire is “jumped “ off of the right one correct? That would mean that both taillights would blink if the right directional was on? Should the left power/directional/taillight have its own wire from the relay?

When I step on the brakes both light light up. Left is dimmer tho

I’ll check voltage when I get home from work. I started this project way too late last night. Haha

Yeah, I wasn't thinking straight - you are correct on that jumper - there isn't one.

 

[73FJ40]

Your wires are 50 years old - a new wire is likely the easy way out. I think the blinker filament is the only one that blinks and is the running light, the brake filament is brakes only. I think my blinker connector is under the dash. Its early and I'm sick - sorry

They went to a lot of work to provide color coded wires and a diagram. You should consult the manual. free downloads

Land Cruiser Factory Service Manuals (FSMs)

Factory service manuals (FSMs) for your Toyota Land Cruiser ! From the 1950s to the present!

www.cruisercult.com

OEM 72 FJ40 has rear combination lamps, only a single, round red lens and a single bulb with two filaments.

Both filaments run on 12 volts. The low wattage filament is only the running light. The high wattage filament is both brake light and turn signal. The circuitry makes the high wattage filament blink when the brakes are activated with the turn signal on.

Dim lights are due to low voltage. Low voltage is commonly the result of poor ground, otherwise, inadequate supply voltage.

The OEM combination lamp does not have a ground wire. The lamp gets its ground through the bolts holding it to the frame. The frame is connected to the negative battery terminal. Any corrosion along that path reduces voltage.

 

[4joggin]

OEM 72 FJ40 has rear combination lamps, only a single, round red lens and a single bulb with two filaments.

Both filaments run on 12 volts. The low wattage filament is only the running light. The high wattage filament is both brake light and turn signal. The circuitry makes the high wattage filament blink when the brakes are activated with the turn signal on.

Dim lights are due to low voltage. Low voltage is commonly the result of poor ground, otherwise, inadequate supply voltage.

So on my left taillight. Only one filament works for all functions, taillights, blinkers and the brakes. The other filament doesn’t work at all.

The right side works great. One filament for the taillights. And the other filament works for blinker and brakes. Both filaments work as they should.

I have a feeling I’m in for some work

 

[pb4ugo]

So on my left taillight. Only one filament works for all functions, taillights, blinkers and the brakes. The other filament doesn’t work at all.

I have a feeling I’m in for some work

This is likely your problem. The bulb is designed to go in the socket only one way. It has 2 pegs on the side of it and they are staggered in relation to each other. The socket has corresponding female holes to the pegs. It is made this way so the contacts on the bottom of the bulb align with the contacts in the bottom of the socket. One contact in the socket is for running lights, the other is for brake/turn.

 

[4joggin]

This is likely your problem. The bulb is designed to go in the socket only one way. It has 2 pegs on the side of it and they are staggered in relation to each other. The socket has corresponding female holes to the pegs. It is made this way so the contacts on the bottom of the bulb align with the contacts in the bottom of the socket. One contact in the socket is for running lights, the other is for brake/turn.

So one power wire runs both posts? Or is one solid green wire for the taillight post and the green with white stripe for the blinker/brake post/filament?

 

[pb4ugo]

Idk, what the colors are. 1 is for the tail light, the other is for turn/brake. You can use a test light or meter to determine which is which.

 

[pb4ugo]

Notice the pegs on the metal sides of the bulb. They are staggered, then look in the socket and you will see the slots are staggered.

 

[pb4ugo]

This ensures the contacts are aligned with each other.

 

[73FJ40]

"o one power wire runs both posts? Or is one solid green wire for the taillight post and the green with white stripe for the blinker/brake post/filament?"

How did you come up with "one wire runs both posts?" You are not thinking. There are two wires going to the lamp that works perfectly. There is NO ground wire. One wire is for the running light filament, the other for the stop/blink filament. Take the bulb out and LOOK into the socket. Confirm to us that you understand how these lights are supposed to work....

It's likely the solid green is for the running light. Solid green is the Toyota early FJ40 conventional harness wire for running lights (side marker and license plate as well).

If the new combination lamps are identical, why don't you switch the lamps from side-to-side to confirm left is good when hooked to the right side harness and the good right has the same symptoms as the original left. Don't forget the combo lamp needs to be attached to the frame to pick up ground.

does the left side marker light come on with one pull on the headlight switch? Does the left combo lamp come on as well? When the left combo lamp is blinking, does the left side marker blink? The dim left side combo lamp could be that the harness wires are crossed or butchered, and the running light, stop and blinker feed is all going to the low wattage filament on the left side harness. Report back.

 

[4joggin]

Thanks for the help guys. I ended up peeling the harness back and found the green with orange tracer wire had a few strands holding it together. With my home made jumpers I hooked them up to the left taillight and everything works as it should. Nice and bright. And both filaments are working correctly. I ended up taking some paint off the bumper to help grounding as well.

Tmw I’ll be splicing it out and de-butchering the rear harness.

Again, thanks for helping me out. One more item checked off the list.

 

[73FJ40]

Thanks for reporting back with success. Too often, others have asked for guidance and never report back.