Trailer Lights not working

doadea [OP] · 07-17-2011, 11:05 AM

Hi All!

I have a 2007 FJ Cruiser which I just purchased. It came with the Factory OEM trailer hitch and harness pre-installed. I hooked a trailer up to it and NONE of the trailer lights work. The trailer lights work fine when hooked up to another truck so I know it's not the trailer.

Here is what I have checked so far:

1. Both trailer fuses under hood are fine
2. The Blue relay for trailer under hood is fine.
3. The convertor box under dash is there, however I have no way of checking it for functionality.
4. Everything else seems as if it is hooked up properly. I reviewed the wiring diagram I found on this site.

The trailer lights will still not work. Any ideas?

Thanks in advance.

**FJess** · 07-17-2011, 11:27 AM

Did you have the trailer connected to the hitch when you tested it? I recently had to replace a light on my trailer and noticed that it wasn't grounded unless it was actually connected to the hitch. Just connecting the wires did nothing and I was freaked out until I hitched it up and everything magically worked. I don't know if this is normal or something quarky with my trailer, but you might try that if you haven't already.

doadea [OP] · 07-17-2011, 11:29 AM

Quote:

Jesster previously said:

Did you have the trailer connected to the hitch when you tested it? I recently had to replace a light on my trailer and noticed that it wasn't grounded unless it was actually connected to the hitch. Just connecting the wires did nothing and I was freaked out until I hitched it up and everything magically worked. I don't know if this is normal or something quarky with my trailer, but you might try that if you haven't already.

Thanks for the reply, but yes I did indeed have it hooked up to the hitch ball, the safety chains were on it as well, hooked up as if I was about to drive off with it.

**FJess** · 07-17-2011, 11:37 AM

Bummer. I'm new to the whole trailer thing and not good with electronics at all so that was my only idea.

There's actually a trailer/towing tech sub-forum here that might get you a more informed answer. I'd maybe try posting this over there if a moderator doesn't move it there for you soon.

snafu58 · 07-17-2011, 11:48 AM

Is the trailer plug in wired into the FJ or is it just There. Sounds stupid on my part. But if what you say in your OP is true, then there has to be a disconnect wire or dead short.

doadea [OP] · 07-17-2011, 11:52 AM

Quote:

snafu58 previously said:

Is the trailer plug in wired into the FJ or is it just There. Sounds stupid on my part. But if what you say in your OP is true, then there has to be a disconnect wire or dead short.

Yes, it is there and plugged in. I followed the line all the way up and inside the rear of the FJ just to make sure. The only thing I can think of is that the converter box is bad.

snafu58 · 07-17-2011, 11:58 AM

I agree, can you buy a circuit tester at an auto parts store and check it? My thoughts are trace it back to a failure/good point.

photosit · 07-30-2012, 08:41 PM

I am having the same exact issue. I have done all of the same things and have come up empty handed. The trailer is grounded correctly and works fine on our 4runner. The FJ is not working at all and I am feeling like banging my head against the wall at this point! Were you ever able to figure out this problem?

**Smalldog** · 07-30-2012, 09:59 PM

j

Quote:

photosit previously said:

I am having the same exact issue. I have done all of the same things and have come up empty handed. The trailer is grounded correctly and works fine on our 4runner. The FJ is not working at all and I am feeling like banging my head against the wall at this point! Were you ever able to figure out this problem?

buy a LED plug-in hitch tester at autoparts store. The LEDs tell you if the hitch connector on the FJ is pushing power to the trailer plug. If the tester indicates power, it's probably a blown bulb on the trailer if it's an LED trailer light system.

doadea [OP] · 07-31-2012, 06:30 PM

Just an update on this. I did get it working. I had to run a ground wire from the trailer to the back of my FJ. It's weird because my other truck works fine without the ground. What I did was I drilled a hole on the trailer near the hitch, and put a bolt there. I ran a wire from that bolt to the ground wire in the harness in the back of the FJ. Worked from then on out, except I have to make an extra step to hook up that extra wire each time.