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View Full Version : Trailer lights - - what is the solution ??


Jimmauburn
08-29-2008, 09:23 PM
Okay all I need some more help. I have brake lights and turn signals but I have no running lights. I have checked the ground and have checked the connections. I have voltage coming from the truck but once it hits the trailer I have nothing. What to do ? Where to start ? Is there a way to trace it from light to light ?? Will some work while some will not from front of trailer to rear ?? All the boats and trailers I have had I have never had any trailer light issues so I am at a loss on this subject. Help !!

TMCNo1
08-29-2008, 10:23 PM
Okay all I need some more help. I have brake lights and turn signals but I have no running lights. I have checked the ground and have checked the connections. I have voltage coming from the truck but once it hits the trailer I have nothing. What to do ? Where to start ? Is there a way to trace it from light to light ?? Will some work while some will not from front of trailer to rear ?? All the boats and trailers I have had I have never had any trailer light issues so I am at a loss on this subject. Help !!

Check all the grounds for each light, somewhere you've got a bad ground!

Gamble
08-30-2008, 09:09 AM
Take a test light, ground it good, and check to see you have power on the running light wire. This should be the brown wire. Check at both lights. If this wire has power, either the bulb is bad for the running light, or you have a bad ground. Don't know which light you're using, but one bulb has 2 elements. The element for the talil light portion could be bad. Also, to help verify the ground issue on the trailer----turn on the hazard lights of tow vehicle. These lights should blink at the same time as the brake lights on the trailer. The brake lights on the trailer should seem fairly bright. If the lights flash alternately, and are dim, you have a ground issue. Hope this helps.

Skipper
08-31-2008, 12:00 PM
Had the same problem when I bought my '95 Prostar. Because your tail lights work then you are getting voltage to them. At some point along the wiring from the tongue to the tail lights there will be wires that lead to your running lights. The first thing to do is use a voltage tester to verify whether or not voltage is leading to your running lights. With the trailer connected to the tow vehicle and the lights turned on: (be careful or you can blow a fuse by shorting the test probe while doing this)

#1: Connect the ground to a good ground source and just touch the probe to the end of the wire leading to the running light. If the probe lights up, you have power going to the running lights.

o If not, trace this wire back to the main wire that leads from the tongue to the tail. Check the connection. If voltage is getting to the tail, this should be the source.

#2: If you have voltage at the end of the wire leading to your running light, then remove the plastic cover and the bulb to access the connections. Use the same ground location and touch the probe at the connector. If the probe lights up, you have power at the light fixture.

o If not, remove and inspect the fixture, itself.

#3: If you have power inspect the bulb. If the bulb is good, then the problem is the ground at the fixture itself. You have established that there is voltage travelling all the way to the fixture, the fixture is in working order, and the bulb is good. However, you have not been sharing the ground from the fixture.

If it is the bulb, replace and go to #3.