lighting problem help

[ichthos]

While I am waiting for my new head gasket, I decided to to check my electrical system after putting in a new harness. The problem is that the right tail light is much brighter than the left. Any ideas what the problem may be?
Kevin

 

[leecreek]

Try the other filament if it is a dual filament bulb.

 

[DrEntropy]

Sounds like the two power wires are bass-ackwards.

 

[ichthos]

I don't understand what you guys are saying. I did try a different bulb with no change in the dimmer light. Would I just reverse the position of the green and red wires in one of the tail lights? The way it is wired currently is that as you face each tail light, the red comes in on the left and the green on the right. The black goes to the bottom. I thought it might be a grounding problem, but I was pretty meticulous in cleaning all connections. I have never seen the lights on in this car until now, but it looks like the right tail light is extra bright, and the left tail light is about right for light intensity.
Kevin

 

[Trevor Jessie]

Yup switch the wires (assuming the bulbs are the same). One of the sockets may be upside down.

 

[ichthos]

The bulbs are the same. I will try switching the wires around and let you know what happened.
Kevin

 

[DrEntropy]

:thumbsup:

 

[ichthos]

Even though the two lights have the Lucas number, they are definitely different. I thought I had followed the wiring diagram to the letter of the law. To make a long story short, I switched the wires on the newer light, and both tail lights work now. I am not sure if I will ever totally understand the wiring on this car. In any case, thanks for the advice.
Kevin

 

[Deleted member 8987]

Easy.
The lights and sockets aren't much different than other cars.
1157 type bulb, one filament (one pin to case) is brighter than the other.

High Element 12.8V, 2.10A, 26.8 Watts, 32 candela, 402 lumens

Low Element 14.0V, 0.59A, 8.3 Watts, 3 candela, 38 lumens

High is brake and turn, low is tail light.
Swap the wires around (common case/socket ground) and the high will be tail, and you'll never see a turn signal or brake light through it.

 

[JPSmit]

I am not sure if I will ever totally understand the wiring on this car.
Kevin

you have learned well grasshopper.

 

[DrEntropy]

I am not sure if I will ever totally understand the wiring on this car.
Kevin

you have learned well grasshopper.

Joe Lucas was a practitioner of Zoodoo... combo of Zen & Voodoo. Don't TRY to understand it, just revel in the knowledge that it WORKS. :wink:

 

[Deleted member 8987]

I am not sure if I will ever totally understand the wiring on this car.
Kevin

you have learned well grasshopper.

Joe Lucas was a practitioner of Zoodoo... combo of Zen & Voodoo. Don't TRY to understand it, just revel in the knowledge that it WORKS. :wink:

sometimes.

 

[DrEntropy]

Other times it'd be best to have good wiring diagrams.

But it varies.

 

[highhilleer]

It is pretty much standard for tail lights that use a single bulb with dual filaments to be wired this way. The brake and turn signal lights need to be seen during daylight whereas the tail light is primarily needed at night. Hence, the brake and turn signal need to be brighter than the tail light.

 

[The_architect]

Kevin,
You should not be able to fit a single filament bulb into a socket designed for a two-filament bulb, so I would advance the theory that this is probably NOT the problem. It's your grounds.

I just went through this with a brand new wiring harness. The ground wiring on the rear left side does not connect to the rest of the harness--it is isolated. The ground wire on the left side connects the two lampholders on that side together and that is all. I found this out the hard way--after I actually pulled the harness and took it apart.

This poor bit of engineering is NOT to be found on the wiring diagram.

Here is what I found out: On my harness, all of rear lampholders are only grounded to the car body, so if the screw holes are corroded they are not going to work well--and I don't see how you could clean them well without running a tap into the screw holes. In my case on the left hand side all sorts of funny things were happening, such as the running lights flashing when the turn signal was turned on.

Since I had the harness out anyway, I connected the left and right grounds of the lighting circuit together, and ran a dedicated ground all the way up to the front of the car. Try grounding your left hand turn signal to the bumper or any other good known ground and see if the light doesn't shine brightly.

Charlie