Driver's side rear light

[gogurd1946]

I have a Keystone Avalanche 300RE fifth wheel. The rear light on the driver's side is dark. Have changed the bulbs but still no light. Haven't travelled any further into the problem. Since the problem is isolated to the driver's side I'm thinking the problem does not involve the junction box at the 5th wheel hitch. Before I dig further, I would appreciate any input that may be useful. Thanks for taking the time to help me out.

[sourdough]

It's obviously either a ground or voltage issue. A VOM will tell you which and where. Hopefully you have one. If so, and need help let us know, if not, please say so as well. Trying to run an electrical issue without a meter is very difficult.

[gogurd1946]

Thanks for your response. I will tackle the problem in the next few days and will take your advice. If I have further questions I will followup on your response. Thanks again.

[JRTJH]

The way it sounds in your first post, the tail light AND the brake/turn light are both inoperable. If so, chances are it's not a voltage issue. The tail light and the brake/turn lights are on different circuits. So, I'd guess it's either a faulty socket or a bad ground. This is a "long distance guess" but I think you'll find the ground wire behind the light fixture has come undone.

[gogurd1946]

Thanks for your "long distance guess ". I will check both the socket and the ground wire behind the socket. Appreciate your response. Best regards.
gogurd1946

[gogurd1946]

Earlier I posted that I had a problem with my driver's side rear light on my 5th wheel. I received a couple of suggestions and followed up on them yesterday. After removing the light fixture I was able to determine the the wiring connections are OK. I may have suggested in an earlier post the there was no power to the rear light. There is power. When the full light package is on the light works however if I put on the turn signal or put on the brake lights nothing happens. Since I have power and all the wires check out O K do you think it could be the light socket or something else I might be overlooking. Thanks for you help.

[notanlines]

"if I put on the turn signal or put on the brake lights"
Using a simple test light only (no more than $4) while someone pushes on the brake pedal and have the turn signal operating for that side, check to see if your tester lights up when you touch the probe to the appropriate wire.

[flybouy]

Earlier I posted that I had a problem with my driver's side rear light on my 5th wheel. I received a couple of suggestions and followed up on them yesterday. After removing the light fixture I was able to determine the the wiring connections are OK. I may have suggested in an earlier post the there was no power to the rear light. There is power. When the full light package is on the light works however if I put on the turn signal or put on the brake lights nothing happens. Since I have power and all the wires check out O K do you think it could be the light socket or something else I might be overlooking. Thanks for you help.

This is a little confusing. The easiest way to check the turn signal/brake light is to turn on your 4 way flashers as there is one circuit for both. Typically there is a dual filament bulb that handles the running and stop/turn function. So turn on your parking lights and the 4 way flashers and check the socket. You should have one contact with constant voltage and one contact with voltage going on and off in rhythm with the other side flashing on and off.
If voltage is present then it must be the bulb or contacts from socket to bulb.
If no voltage, then first check the 7 way connector from the truck to trailer. Often times a little dielectric grease on this connection will solve connection issues. Hope this helps.

[hornet28]

Follow flybouys advice as he's right on

[Steveo57]

If your seven pin cable goes into a box at the front of the RV take off the cover and check everything tight there and check your voltages there. You should have voltage on the red wire there for the left turn signal/brake light. If that's good then you can check at the light. If it's an LED fixture you have to pull the fixture out and it will have a 3 pin plug where you can check voltage. That should narrow down the problem.

[Wingerdinger]

I know this post is 10 days old, and probably got solved, but the first thing that comes to mind is a bad ground. Commonly, in a brake light/tail light fixture, if the ground goes bad, and you turn on the brake light AND the tail light, the brake light will light at a reduced brightness, and the tail light will go out. It uses the path to the tail light for the return voltage. As an old backyard car mechanic, I've seen it 100 times.