Weird problem - any ideas?

[Stepside]

Like Prop said: Check all soldered connections,

But I would Not be surprised that the Installer did Not solder
and simply 'spliced in' with crimp connectors
and one of them did not make good contact.
Shrink tube and soldered connections is the way to go.
Looks like you have a resistance problem causing a voltage drop. Check voltage at each light.

 

[pat'sRAPTOR]

I've used spliced connectors and soldered and all sorts of connectors before with no issues it has to be the gauge. And itight not seem like it would make a big difference but it will. I run 10 gauge on all my lights no matter where they are mounted just I be on the safe side. If the grounds were bad the lights wouldn't work at all if it was a bad connection they would flicker or wouldn't work at all but since the one is dim and brightens up when the other is unugged then the wire isn't supplying the full amount of amps needed to run them both

 

[PropDr]

If the installer used the supplied wiring harness and just extended the lead wire with an 22 gage both lights would be dim, not just one; or the lights would be normal with only the wire getting very hot very quickly.
A 14 gage wire should be more then sufficient considering the low current draw of the D2's


PS, if the combined grounding is insufficient both lights would be dim; if the grounding problem is with only one of the lights it will pull ground through the other one and one will be dimmer.

 

[STUTIDE]

Looked tonight and the ground and power lead were both run up to the front. They just extended the factory wiring harness. Ground wire was secure but seemed pretty thin. 16 maybe? Grounded to main ground bolt on engine bay wall.

 

[MTF]

I'm surprised they ran the ground back to the front, I'd cut the grounds and attach them to the bolts on each light, maybe with a second nut.
And you can cheat (poor boy way) by using both wires from the front and tie them together for power.

Have tried to power the lights directly to the battery with two long heavy gauge wires just to make sure that will solve the problem?

 

[The Car Stereo Company]

due to the resistance present in dc applications, the ground path should be as short as possible. guage of wire, location of ground, and type of ground can cause these issues. if you pull the tail light you can scrape the paint behind it and then ground there. afterwards spray the ground with amsoil to prevent the bare metal from rusting. i found this to be the most protected location for a ground in the rear of the truck.

 

[iSurvive]

Any issues I've had with Rigid lights are a bad ground or wire that's too thin.

Did you try switching the plugs to see if it happens with both lights?

 

[1ntheoc]

I've got 4 dually's, 4 D2's, a 30" E-Series and a 50" E-series installed on my truck. I'm fairly certain the wires in the harness are plenty big. You have some type of connection problem. I ran into a similar problem at one point and I can't remember exactly what I did wrong, but I had a poor connection somewhere...

 

[STUTIDE]

Im gonna try some things that were suggested above and will let you know. ALl great stuff and I greatly appreciate all the help! These guys are good at this stuff but I am surprised they ran the ground that long as well. The original wiring harness was about four ft long as went into a relay switch (which I did not use since I wanted it on my upfitter switch). Im positive they just cut it off by the relay and continued everything up front (along with the ground). That would make it a long ground wire. That with a thinner wire has GOT to be the problem. Im going to switch out the lights to make positive its not the one light.

 

[STUTIDE]

You guys were right on the mark! Had an electrical genius help me tonight and we ran 10 guage all the way to the front - grounded both back in the back - and put a resistor between the 2 lights and now ZERO PROBLEMS! There is the slightest difference in color between the 2 but nothing like before. One is a little more purple base in color while the other is a little more yellow but not that big of deal. I think that could be tied some how to the diffusion lens. THANKS for all your help!!!