Left back tail light

funnygirl · 07-19-2013, 12:27 PM

Help - getting ready to take a trip. The trailer left back tail light goes on, but will not do brake light or turning signal. Bulb is good and output is good. I called CruiserRV and they kind of said "duh". I called a dealership and they said there must be a break somewhere in line - either on top of trailer of underneath. All of the running lights work. 2009 21ft. X210. Can someone please respond with an idea asap. Thanks much.

Dillinger-63 · 07-19-2013, 01:30 PM

I have the exact same issue on our 07 FF 189FBS. It is at the dealership where we bought it, but I'm not sure what they have come up with yet for a fix.

funnygirl · 07-19-2013, 01:50 PM

Thanks for the reply. My guy is talking to CruiserRV now. I see where you're from northern Illinois. I moved to Missouri from Elgin, IL. Did you buy your camper at Vacationland? We're leaving on trip in a couple of days - if you find out anything, will you please post it? Thanks.

Dillinger-63 · 07-19-2013, 04:36 PM

We purchased it from Pontiac RV in Pontiac Illinois. Yes, I will keep you posted as we find out. I had four issues with our FF, and I was told parts were ordered, but I'm not sure if it was for this problem.

webslave · 07-19-2013, 05:32 PM

If you are certain the bulb (both filaments) are good, then you have a problem with the yellow wire. Now, whether the issue is the yellow wire from your tow vehicle or the yellow wire on the trailer is something you'll have to test. That yellow wire handles the turn signal pulse and the brake light power. If the voltage pulses, the light goes on and off; turn signal. If the voltage is constant, the light goes on and stays on until you take your foot off the brake. Same wire, dual useage.

Have a VOM (Volt Ohm Meter)? If you don't, you should get one (they aren't that expensive and easy to learn the basics with and an invaluable aid for troubleshooting 12 volt issues) and you can do a lot of the trouble shooting yourself.

To test the vehicle's ability to transmit the voltage for the "flash", you would stick the positive probe (red) from the VOM (set for DC volts; anything on the dial greater than 12V) onto the pin for the yellow wire (looking at the connector, it is the pin at 9 o'clock position) and the ground probe (black) against a ground point; any bare metal in the area. With the motor running and the turn signal on, the needle on the VOM should bounce. It isn't important, for this test to see what the volt reading is, just that it bounces. That "bounce" indicates that the vehicle is sending the "volt pulse" that makes the turn signal light. If you don't get a "bounce", then the problem is with your vehicle. If you get a bounce, then the problem is with the plug (on the trailer) or the wire from that plug to the back of the trailer.

Again, the VOM can help. Take a straight pin (or safety pin) and stab it through the insulation on the yellow wire on the trailer. Near the plug. Set the VOM for "Ohms" and touch the probes (red and black) together to let it know what "zero" feels like. Most of the newer VOMs will auto-set zero from that. I've got several VOMs, one that is an antique and I have to physically turn a wheel to set zero (showing my age). Once you have zero ohms set, take either probe and touch it to the safety pin or straight pin and to the clip that has the yellow wire attached to it (looking at the end of the plug, it should be at 3 o'clock if memory serves me. Watch the orientation of your plug - it has a hump that should be at the top (12 o'clock) and your other pins are based on that orientation. Your meter should go straight to zero on the scale or very near it. That means that the yellow wire is, indeed, got a good connection to the plug and the plug is then removed from the list. If the meter shows "infinity" or anything really above 50 ohms, then you've got a problem with the plug.

From that point on, you can still use the VOM to test with. It isn't elegant (I've got "elegant" tools that make testing easier, but, they are expensive and take time to learn how to use and first reach is still for my trusty VOM and I take it with me in my RV toolkit on every trip), but, you've just eliminated the "plug to safety pin" hunk of plug tip and wire. Just get another safety pin and stick it in the yellow wire further towards the rear of the trailer, but, close enough to the first safety pin, so that your test leads will reach between them. Test from safety pin to safety pin...it should read zero. If it reads zero, then the wire is good from the first safety pin to the second. If not, the wire is likely broken between the safety pins. Make sure that the pin goes through the center of the wire so that you don't get a "false positive".

If that hunk of wire checks out OK, then take the first pin out and move it closer to the rear of the trailer (like leap-frogging) and test the next hunk of wire. If that checks out OK, then leap-frog again.

You get the idea. It isn't elegant, it is time consuming and you'll learn a lot more about how your trailer is wired than you probably wanted to know, but, is good to know anyway. For instance, did you know that the trailer's umbilical (that 7 pin cable) actually, on most FF models, goes to the box where your main disconnect is? That "black box", if you pull the cover, is the distribution point for all the wires from the umbilical and the battery - you could have a loose connection in there. Most of the connections in that box are done with wire nuts and they do come loose and / or get corroded. If you come to a wire nut on the yellow wire, take it loose and look at the wires. Are they twisted together tightly, not corroded? If they are OK, then carefully, but, firmly put the wire nut back on and tighten firmly and continue with the testing...

Sounds a lot more complicated than it is and there are better tools that can do it easier, but, they are expensive and have their own learning curve to know how to use effectively. A VOM is low cost, low tech and is good for all sorts of electrical testing and trouble shooting both inside and outside your RV. I don't leave home on a trip without mine.

If all of that sounds scary or "beyond you" (it really isn't, but, it can be intimadating), then your only other recourse is a service facility (where they will do, basically the above) where they can do the "tracking down of the problem", but, it really isn't difficult as it is a straight line circuit. Your brake pedal gets pushed down. Throws a switch that lets 12v flow down the yellow wire to the vehicle's 7 pin plug, through the trailer's 7 pin plug, then continue down the yellow wire, eventually winding up at the tail light where it lights the brake/turn signal element. Somewhere in that straight line, you have a "break" in the path.

funnygirl · 07-21-2013, 08:09 PM

Thank you Webslave. I was hoping you would answer as I have followed your suggestions since I've had the trailer. I will be checking out the yellow wire tomorrow morning. I'll let you know what happens. Thanks, again.

funnygirl · 07-24-2013, 04:05 PM

Mystery solved --- so simple. Problem was the fuse in the tow vehicle. Can't believe hubby spent so much time on wiring issue. Oh, by the way, our camper does not have a yellow wire. They must have changed some of the wiring from the 2008 and 2009 models. I bought a couple of extra fuses just in case. Thanks to those who replied with possible fixes - really appreciate your input. We are now "happy" campers again!

webslave · 07-24-2013, 09:27 PM

Glad you found the fault. That was why I always suggest starting with the tow vehicle first...find out if it is actually sending the voltage to the plug.

As for the "yellow" wire... Now you know why the manufacturers won't give out plumbing or wiring schematics. They know what it should be, but, if you've ever owned a British car, they don't always follow the "rules". It isn't that they don't have the wiring diagrams, they just know that they aren't accurate and aren't worth the paper they'd be printed on.

For future reference, here is a link to etrailer's wiring diagrams page, one of the best I've found anywhere. It will show you what a 7 pin (a 4,5,6, too) wiring is supposed to be. For those that don't have the proper colored wires, the pin #'s will be correct even if the wire color isn't. If you know that the left turn signal isn't working, you can look at pin #5 and know that, even if that wire is lavender, it is the wire that goes to the left turn/brake signal. Should have put this link in the first post, but, thought it (the first post) was already too long.

Etrailer.com Wiring Schematics

As you found out and I put in my post...don't always assume the problem is with the trailer. A trailer's wiring system is very simple and very little actually goes wrong with them. The fault of a problem like that usually lies in the tow vehicle's system. A bad fuse, a bad relay, a faulty plug, corroded plug, etc. Start at the source and work back. That's true for any problem you may be chasing in your RV, whether electrical, water or television/cable signal.

Good for you on finding the fuse!

profdant139 · 07-24-2013, 10:22 PM

I just gotta put my two cents in here -- I just can't believe how detailed and useful webslave's posts are. Lots of people chime in with good stuff, but this guy is batting a thousand. I really appreciate your stuff -- thanks so much!!

Dillinger-63 · 07-26-2013, 02:27 PM

We got our FF back and the left tail light issue was due to a bad wire on our trucks plug in. By they way, when the dealer had the light apart there was no yellow wire on out model. white/black/red were the colors.

Mimitjc@gmail.com · 09-26-2021, 12:45 PM

Quote:

Originally Posted by funnygirl

Mystery solved --- so simple. Problem was the fuse in the tow vehicle. Can't believe hubby spent so much time on wiring issue. Oh, by the way, our camper does not have a yellow wire. They must have changed some of the wiring from the 2008 and 2009 models. I bought a couple of extra fuses just in case. Thanks to those who replied with possible fixes - really appreciate your input. We are now "happy" campers again!

I'm hoping you will see this, a year later. What fuse did you replace? Were having the same issue and no yellow wires.

Thanks

Floridacamper · 02-02-2022, 09:04 AM

I am having the same issue with the left tail light not showing the brake light or left turn signal. Thanks for the suggestions! I will give them a try!!