Voltage drop thru Dodge trailer lights connector

[groser]

I have 2001 with tow package. I get anywhere from a 1 to 2 volt drop at my 5th wheel brake/tail lites when connected, drop dependent on how many lites I turn on. I'm connected into the standard Dodge 7 pin receptacle that came with the tow package. Even when not connected I can measure a slight voltage drop, about 1/2 volt at the receptacle. I suspect this may be normal. The drop is NOT from the 5th wheel. If I connect to my 5ver lites directly from the 5ver battery I get no voltage drop. I noticed the voltage drop because my brake and tail lites seem dim during daylite hours but fairly visible at night. Since I have the tow package I would not expect any voltage drop from a 5ver with normal complement of running and signal lites.

Strange thing is I get same voltage drop wether truck is running or not which does seem to suggest the truck wires are to small.

Has anyone else measured voltage at the tail lites on their rigs and at the Dodge receptacle? I asked Dodge for amp capacilty at the receptacle but got no real answer. They suggested I put in a relay type circuit but that's +$100 I don't think I should have to spend on a truck I bought from Dodge specifically for towing.

 

[WestTN]

The wires are typically 18 ga. There will be some voltage drop when drawing several amps through 30 to 50 feet of wire. the truck alone has around 20 feet, and then your trailer will usually have around 10 feet or more plus the length of the trailer. If you really need those lights brighter, then relays could help provided they are fed with a 12 ga wire (fused) to greatly reduce the losses from the truck. Another solution would be to look for LED bulbs for the tailer. This would probably cost no more than relays, but would be easier and likely longer lasting. The reflector quality in many trailer light fixtures is deficient as well. I put silvered mylar tape in mine.

 

[GAmes]

I had the same problem even with the trailer running lights on a seperate switch using heavier gauge wire. The problem was that the ground going to the 7-pin connector was corroded. You might check that first.

 

[bmoeller]

Corroision on the connections would also be my first place to look. Hot side and ground. Have to deal with that on the big trucks as well. It is worse with aluminum trailers. Whenever different metals touch aluminum, it causes oxidation.

 

[jelag]

I changed all my lights on the back of my trailers to LED's... ... they draw much less current... and should last the life of the trailer.....



I thought about putting a relay in the trailer... and run all the lights off the trailer battery using only the connector to signal the relay... ... and let the truck charge the trailer batteries... . and in fact this would have been more cost effective at first... .



But we has a few lights out... and kept having problems with moisture inside the len's so the sealed LED's were the way to go for me.....

 

[groser]

More info

My wires are already 12 to 16 gage on truck and 14 gage on trailer. I now suspect, if I have a problem, it could be where they spliced into the Dodge receptacle wires to add another receptable in the truck bed. I get the same voltage drop at both receptacles which could be caused by a corroded ground

since that's common.



I previously switched the brake/tail lites to LED but it didn't help much. LEDs actually provide less lite in the "normal" spectrum (according to LED web site) but also less amp draw which should have brought up the voltage. Today I "lighted" the brake and tail lites from truck, had 10. 7 volts at rear of trailer, then jumpered in the trailer battery which brought voltage up to about 12VDC but brightness increase was hardly noticable. My wife could barely tell when I jumpered in. Maybe I'll put back the regurlar incadesent bulbs and do same test!!! Or switch all lites including running lites to LED.



I'm going to try the silver Mylar tape idea. The reflection is poor and I tried cleaning them but the reflectors still stayed dull even after I applied metal polish. If that brightens it up maybe I'll just live with the voltage drop.

 

[starkmr]

My wires are already 12 to 16 gage on truck and 14 gage on trailer. I now suspect, if I have a problem, it could be where they spliced into the Dodge receptacle wires to add another receptable in the truck bed. I get the same voltage drop at both receptacles which could be caused by a corroded ground

since that's common.



I previously switched the brake/tail lites to LED but it didn't help much. LEDs actually provide less lite in the "normal" spectrum (according to LED web site) but also less amp draw which should have brought up the voltage. Today I "lighted" the brake and tail lites from truck, had 10. 7 volts at rear of trailer, then jumpered in the trailer battery which brought voltage up to about 12VDC but brightness increase was hardly noticable. My wife could barely tell when I jumpered in. Maybe I'll put back the regurlar incadesent bulbs and do same test!!! Or switch all lites including running lites to LED.



I'm going to try the silver Mylar tape idea. The reflection is poor and I tried cleaning them but the reflectors still stayed dull even after I applied metal polish. If that brightens it up maybe I'll just live with the voltage drop.

What method was used to splice in the truck receptacle? You could have corrosion if they are exposed, if so, clean them up and use liquid tape to seal the connections.

 

[JimB1]

The voltage drop shows for sure something is failing and/or installed wrong. It'll quit entirely at whenever is the worst possible time. Stick with solving the voltage drop while it's relatively cheap and easy. I'm guessing, but . 1V to . 3V max drop accross entire length of system with everything running sounds about right to me. Some of the other upgrades sound pretty good. Jim.