No Turn Signals or Brake Lights on Trailer

[SkyBound]

Hey all, been a while since I've posted here but I've come across a small issue that I haven't been able to figure out myself. Just got back from our first trip and everything worked great except for my trailer's rear brake lights and turn signals. All lights light up when I turn on my truck lights, so the bulbs are working but just no response to brakes and flashers. Trailer brakes work, all connections are good, and I hooked up my cargo trailer to the truck and those lights all work properly so it's definitely a trailer related fault.

I'm thinking since both right and left sides aren't working that it's something common to both lights such as a ground, but I'm unsure where the ground is for those circuits. Any help appreciated.

[Stan&Sharon]

I suggest you use a multi-meter and confirm the required voltages exist. Here is a page that explains the 7-Way connector.
You may also want to apply some dialectric greese to the conection.


Do you have ability to connect to a different trailer to see if the problem is with your truck? Do you know someone else who can plug into your trailer to see if it's just your truck?

[SkyBound]

Thanks for the reply. I plugged the truck into a different trailer and it was OK, so it's definitely my Jayco having the issue. I'll try cleaning up the 7-pin plug on the trailer again and put some dielectric grease on it, hopefully it's a quick fix. I did hit it with some electrical contact cleaner yesterday and nothing changed.

[Stan&Sharon]

Hopefully that does it... but your symptoms point to pin#5 & pin#6... Do the running lights work? Maybe it's just the ground (pin#1) which would be easiest to fix - of course you've checked the bulbs, and they're okay? I'm hoping it's just pin#1

[DocBrown]

The screwy part about trailer tail lights is that the grounds are usually just ran to whatever metal is closest to the light. I've seen where it's terminated at the bottom of an aluminum panel on aluminum sided trailers. But tracing the ground pin is your best bet. Also, as suggested you need to use a mutil-meter to find out where the connection fails. For example you may have voltage at the trailer side of the connector, but not at the tail lights. But knowing this starts you down tracing where the issue is.

[JFlightRisk]

snip...[QUOTE=SkyBound;1053132I'm thinking since both right and left sides aren't working that it's something common to both lights such as a ground, but I'm unsure where the ground is for those circuits. Any help appreciated.[/QUOTE]

Your TT is a year newer than ours, which had incandescent bulbs (until I upgraded to LED panels), you probably already made sure the brake/turn filaments were intact. If it was indeed a ground issue, the taillights would be out too. You can run a separate ground wire to the socket to verify that. I'd check the wire connectors in the junction box on the frame next. If the wiring in there has household wire nuts, there may be loose or corroded connections.

[SkyBound]

I had a chance to do some more troubleshooting and I still haven't fixed it yet. Here's where I'm at:

-Truck is 100% not the problem, verified on other trailer
-Cleaned all contacts in the 7 pin connectors, no change
-Checked the main ground on the tongue, and 2 grounds on rear of frame, OK

Here's where it gets interesting...

I pulled the breakaway switch to test that, and I was able to rock the trailer slightly forward and back indicating the trailer brakes were not applied, there was no quiet humming noise coming from the brakes like I have experienced before, indicating again that the brakes were not applied. I came back to the breakaway pin box on the tongue, and it was smoking! I quickly put the pin back in, and it proceeded to melt the plastic pin.

I completely removed the breakaway box and wiring from the trailer and ordered a new one, but I'm trying to wrap my head around this if it is at all related. The trailer brakes were working 100% normal when I was towing it last weekend with no signal/brake lights working on the trailer.

Stumped.

[craigav]

Points to know:

The electric trailer brakes don't engage like that of a vehicle. It takes a little distance (several feet) of the trailer moving forward with the brakes on before they will have any braking effect.

Second point, the breakaway switches are not all that great, they can't handle the current for very long at all before they get damaged, which may also include the wiring to the switch, but the good news is that there was current flowing which is what should be expected and would be normal. However, if one or more of the brake wires was shorted you would also get the same results so it is not a true test that the brakes are actually working or if there is a short in the wiring.

Also, keep in mind that the trailer lights are not on the same circuit as the trailer brakes, however they do share a common connection at the trailer connector, but I suspect the issue is elsewhere, perhaps a poor ground connection which also is in common to the lights and brakes.

~CA

[SkyBound]

UPDATE:

Well I solved the problem! This seemed much more complicated than it actually was, however the symptoms of the problem were misleading.... I ended up having three unrelated failures all at the same time! With both turn signals and brake lights not working, I was looking for something common to both lights, especially since both lights still illuminated with the marker light function.

It turns out both bulbs had corroded on one of the two base contacts in the exact same place, at the exact same time, on both sides. What are the chances?? And the smoking break-away box, although it might seem like it could be somehow related to brake lights, was an independent failure of the unit itself. Who knows how long it was bad for, I just happened to test it during this troubleshooting ordeal.

$25 for new bulbs and a brake break-away box and I'm good to go. Checking the bulbs should have been step 1, but with both exhibiting the same problem and still illuminating with marker light I assumed they were ok.

The one thing that all 3 problems shared in common - corrosion.

[norty1]

Glad you got it repaired. Did you mean break away switch rather than controller?

[SkyBound]

Edited. Thanks for pointing out my error!

[85vf500rr]

I had a similar problem last summer with my 29BHS and found the contacts at the base of the bulb on the taillights were corroded and had gotten hot, the plastic had bubbled up enough on the bulb base to increase the gap and lose contact on the high filament side of the bulbs. I popped into Walmart and grabbed some contact cleaner and new bulbs and was happy to see my problem was fixed. Sorry I didn't see your thread sooner or I would have pointed you to this as our campers are nearly identical. Glad you got it fixed!

[Johnynorthland]

My 5 pin on my CRV wasn’t working properly for the left stop and signal lights, on my stow-away luggage carrier. I closed up the barrel connectors a little with a pair of electrical crimpers to tighten them up and it fixed the issue! At first I cleaned them with contact spray and brushes from my gun cleaning kit but it didn’t help!

[jimmoore13]

Learned something. Thanks.

Question to the OP. Since your rig is a bit older, are your lights incandescent or LED? I'm assuming incandescent, but I'm eager to know.

Observation. Good to know that it's wise to test the brakes "breakaway" switch. Mine saved my bacon once, but I never thought to test it.