brake light grounding issue

matt h · 07-27-2015, 07:35 PM

I just picked up a used Rockwood popup. I am having issues with the brake lights and directional on the trailer. I'm assuming it is a grounding issue, but was hoping to gain some wisdom and tips from the forum to point me in the right direction to troubleshoot the issue. I'm sure this has been posted somewhere previously, but I'm new to the forum and haven't figured out how to fully navigate it

Thanks,
matt h

**Flybob** · 07-27-2015, 07:58 PM

Could be a lot of things. The sockets for the lights could be corroded or there could be a broken wire. You don't say what TV, but many vehicles with trailer hitches and 7 pin electrical connectors have separate fuses for the trailer lights and power. In many cases, ( unless primary function is towing) the manufacturer leaves out the fuses. Check the owners manual for the TV and see if there are separate fuses and if they are installed. If outer skin of PU is aluminum, many times that is used for the ground. The copper wire / aluminum skin connection corrodes causing loss of ground.

uhduh camping · 07-27-2015, 08:14 PM

Your question is a little to vague, but do you have test light? I am guessing light works intermittently? Open up light in question turn appropriate vehicle light use testing light grounded to frame touch positive side of light circuit (green or yellow wire). If test light "lights up" then yes you have grounding issues you have an open circuit(broke wire or bad connection). If it does not light up you have an open circuit or a short (positive wire is rubbing on frame some where but this will typically blow fuse.

If this not intermittent then you need to start at vehicle, ground to car frame and see if test light works at plug and slowly work your way back to trailer light in question.

matt h · 07-27-2015, 08:26 PM

The TV is a Honda Pilot. I installed the factory trailer wiring harness that came with the control unit, relays and fuses, and testing shows the 7 pin connector is working. I'll check all the connections on the trailer.

Thanks,
matt h

rsdata · 07-27-2015, 08:59 PM

used unit probably has corroded contacts on the wire harness... lighting current feeds back in many strange configurations when not ALL connections are good...

now that radio shack is gone I don't know where to tell you to go out and buy some contact cleaner to spray the harness plug... maybe HDepot

try some WD-40 and a small stiff brush to clean the contacts on the trailer... heck the trailer light sockets may even be rusty, in which case you would need to take off the lenses, take out the bulbs, (look for bad bulbs) and then clean the bulb sockets if they look corroded or rusty

matt h · 07-28-2015, 01:02 PM

It gets a bit weirder. I cleaned all of the contacts as suggested, but now I'm getting the CO2 alarm going off when the propane isn't even connected and the heater is not on. Does anyone know if wiring diagrams are posted somewhere in the forum? No luck yet with the brake and signal lights.

Dug · 07-28-2015, 01:21 PM

It seems that you have the same problem that I had , no lights on the trailer. I took it to the dealer, two days later I still had no lights. I started chasing the problem, ended up at the fuse panel under the steering wheel where I found a relay that would go on and after a few minutes it would shut off, so I decided to look through the owners manual. The manual said that if you turn the key on acc after a few minutes it will turn off the trailer circuits off. So I started the engine and every thing now works. That kinda made me feel a little stupid , but somewhat brighter than a Honda mechanic. Good luck.

karrun · 07-28-2015, 01:23 PM

Quote:

Originally Posted by matt h

It gets a bit weirder. I cleaned all of the contacts as suggested, but now I'm getting the CO2 alarm going off when the propane isn't even connected and the heater is not on. Does anyone know if wiring diagrams are posted somewhere in the forum? No luck yet with the brake and signal lights.

I get the CO alarm (not CO2) when my battery gets low. Might want to check that.

uhduh camping · 07-28-2015, 03:26 PM

Start with the basics, is the light you want to be working "on" in the vehicle? Does it work on vehicle? Is it working on the vehicle plug?

mnoland30 · 07-28-2015, 07:08 PM

I struggled for days on my first trailer trying to get the lights to work. A kindly mechanic explained that the first thing to check is the ground between vehicle and trailer. Anytime I'm not sure, I use a jumper cable and clamp it to both the trailer and the truck. That resolves a lot of issues right there. Plugs are supposed to carry a ground across, but often aren't connected. A well used trailer ball will carry the ground current, but a little rust will mess it up quick. Before anything else, check the ground.

As for corrosion, I found on my boat and travel trailers that it is almost impossible to keep water out. The best I did was to seal the top and drill a large hole in the bottom. Like holding a glass under water, it won't fill up, but the large hole allows it to dry out. I changed my clearance lights to LEDs on my Roo the other day, and all of the lights on the windward side had mildew. In NM we hardly know what that is, so I can imagine what it is like in a more humid climate.

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