Tail lights

[Bull22]

Hey ive got a question that is prolly pretty simple.. But its driving me nuts. My tail lights on my cruiser stopped working. My brake lights work fine along with backup and turn signals but when i have the lights on no tail lights. What are the things I should check? BTW its a 74fj40

 

[Poser]

Fuse...just because it may appear 'good' does not mean that it is...take it out and swap it with another one...


Do the dash lights work?

 

[Pin_Head]

Sounds like you have a bad connection somewhere between the light switch and the tail lights. If you look carefully, the tail lights are probably just real dim when you turn the lights on. If the headlights are dim too, the bad connection could be upstream of the switch.

 

[Bull22]

Actually the dash lights stopped working... Is that on the same fuse?

 

[Bull22]

Oh and the tail lights are not dim at all. nothing. And the head lights are real bright.

 

[laguna80]

Sorry to bump such an old thread, but I didn't want to start a new one. Got a question about my tail light. Here's the situation: Been working on my rear lights for a little while now and have got everything almost perfect. Blinkers work, brake lights works, hazards work, passenger tail light works, but drivers side tail light is very dim. It didn't look like it was lighting up, so I took the tail light cover off and found that the tail light was dim. Another thing about it was that the wrong filament was lighting up in the bulb. The tail light filament wasn't lighting up, but the turn/brake filament was the one that was dim. It is only dim when the running lights/head lights are one. Otherwise it is very bright with the turn/brake lights. Grounds are good too BTW. What could be causing only one tail light to be dim? Thanks for all your help.

 

[Poser]

Grounds are good too BTW.

What did you do to verify that the grounds are good?


Have you grounded the lamp assembly other than by the mounting studs or?


You have ran a seperate wire to the negative side of the battery to verify this?

What could be causing only one tail light to be dim?

Tried a different bulb?

Pull the 1157 out and put it in correctly.


Tried 'the bulb' in the other lamp assembly?


What kind/style of lamp assembly are we working with? OEM or 'other'?



Poor connection at a junction feeding that lamp assembly could be to blame. Are there any Scotch-loks in the system?


Have you tried a test light in the bad circuit 'up stream' of the connection for the tail lamp?

How far did you go?

What did you find?




Bad wiring/connection

Bad bulb

Bad ground

Bad lamp assembly


Those are about it options/reasons why this would not work....

 

[laguna80]

What did you do to verify that the grounds are good?


Have you grounded the lamp assembly other than by the mounting studs or?


You have ran a seperate wire to the negative side of the battery to verify this?








Tried a different bulb?

Pull the 1157 out and put it in correctly.


Tried 'the bulb' in the other lamp assembly?


What kind/style of lamp assembly are we working with? OEM or 'other'?



Poor connection at a junction feeding that lamp assembly could be to blame. Are there any Scotch-loks in the system?


Have you tried a test light in the bad circuit 'up stream' of the connection for the tail lamp?

How far did you go?

What did you find?




Bad wiring/connection

Bad bulb

Bad ground

Bad lamp assembly


Those are about it options/reasons why this would not work....

Thanks for the answer. Tried switching bulbs-same problem. When running lights are on, brake light doesn't work on that side. Could this be crossed wires? Tried attaching seperate ground from tail light and that jacked the hazards up. Sorry, I just assumed that since all other lights work aside from that one that the ground must be good. Tested inside the light fixture itself and got 12V. Lamp assembly is aftermarket. I have checked and rechecked the connections multiple times. There are no scotch locs.

 

[cyrilward]

i once had this same problem with aftermarket taillights i found that the wiring from the tail light to the plug were crossed. if i remeber correctly the brake wire and turn signals were swaped not forsure on colors. anyways try swaping your wires on the tail light itself. the wires in the plug will pull right out with the help of a small flat head screw driver

 

[Pin_Head]

The light bulb base or lamp housing has a bad ground. This is always the culprit when the wrong filament lights up.

 

[laguna80]

The light bulb base or lamp housing has a bad ground. This is always the culprit when the wrong filament lights up.

Think I may have found the problem. I messed around with the light bulb base and removed the wires from the base and then slid them back in and now the tail light is bright, but in the wrong filament and the brake light only works when the turn signals are on. How can I run a seperate ground from the lamp assembly? Or should I just go ahead and get a new lamp? What is the best way to fix the grounding issue in the lamp assembly? Right now, it's grounded through the top drivers side running light.

 

[cyrilward]

I still believe your wires are crossed from the light to the plug. Not sold on it being a ground issue

 

[laguna80]

I still believe your wires are crossed from the light to the plug. Not sold on it being a ground issue

I'm not exactly sure what you mean. My light has 2 wires coming out of it, a red and a black. The lamp base is a cylinder with a spring and the two wires passing through that with metal contacts on the end of the wires where the bulb attaches. I tried attaching the bulb backwards to see if the light would light up that way, but no luck.

 

[cyrilward]

what i am suggesting is that you swap the wire placement on the plastic plug from the taillight that connects to your wiring harness. do Not mess with the wire placement on the taillight assembly itself. using a small flat head you can individually pull each copper fitting out of the plastic plug and swap positions.... ALso where did you purchase these aftermarket taillights?

 

[laguna80]

what i am suggesting is that you swap the wire placement on the plastic plug from the taillight that connects to your wiring harness. do Not mess with the wire placement on the taillight assembly itself. using a small flat head you can individually pull each copper fitting out of the plastic plug and swap positions.... ALso where did you purchase these aftermarket taillights?

Came with the vehicle when I bought it. I see what you mean about the wires. I'll try that tomorrow, it's dark now.

 

[slickrock]

You know, I had all these wiring problems too when I got mine. After spending days and just getting more and more fustrated, I decided to rewire from the switches back. Took less time than I wasted trying to fix the OE stuff and works great. Follow proper wiring process and no worries. Might be worth it to just do that.

 

[laguna80]

You know, I had all these wiring problems too when I got mine. After spending days and just getting more and more fustrated, I decided to rewire from the switches back. Took less time than I wasted trying to fix the OE stuff and works great. Follow proper wiring process and no worries. Might be worth it to just do that.

I was thinking of doing that, but I think that I will wait until I need to replace my tub or something worse happens. The problem appears fixed for now. I found a bad connector on the license plate light from when the OP had replaced some of the wiring. Changed that and one other connector and now everything works perfectly. Thanks for all the help and suggestions people! Much appreciated.