Trailer Light Issues

[sjb]

sjb-Are you absolutely sure you have power to the plug? If the tow rig is a GM product with the factory installed trailer wiring you'll likely have separate fuses for running lights.

You know what, I will double check. But I did check all the fuses for trailer lights and did take my handy dandy little tester to the female end of the pigtail on the truck and the trailer light plug lite up both on the 7 pin harness and my 4 pin. So I am pretty sure.

Now that I think of it, I also took a 12 volt gel cell and connected that to the 7 pin male end. I could get the brake lights to light up no issue. But nothing but a small spark from the running lights.

Frustrating.

 

[mezz]

sjb-Are you absolutely sure you have power to the plug? If the tow rig is a GM product with the factory installed trailer wiring you'll likely have separate fuses for running lights.

In fact, there is a separate fuse for running lights in the fuse block, if memory serves me correctly it's a blue (15amp) fuse. Keep us informed.-Mezz

 

[groomerdriver]

Must be no snow with all the feedback on such a lame issue.

IMO...it's not a lame issue at all sjb. Most (?) of us have experienced trailer light issues (at the worst effin' times too) and are here to help you. We want to see you get it fixed and learn what the problem was.

Not all of us are here to argue about sheet.

 

[legend02]

In fact, there is a separate fuse for running lights in the fuse block, if memory serves me correctly it's a blue (15amp) fuse. Keep us informed.-Mezz

Also on a Ford, separate fuse for the running lights. Found this out when my buddy's car trailer kept blowing the fuse running lights and the brake / turn signals still worked. not an issue when your driving during the day.

This winter on the last trip the second vehicle let us know my running lights started to flicker and then eventually went out , brakes and turn signals still worked. Turned out to be the wires on the plug rusted away / fell of the plug for the running lights. I always carry a spare plug so it wasn't that big off an issue 15 minute fix.

 

[snowfish]

Did you remove the newly installed break away battery to check the spaghetti connections below it? The reason, that I ask is you said..............

I installed a new (break away) battery and the lights came on the trailer without being hooked up to the truck

Since the break away battery is connected to only the brakes, this says something got crossed.
Also............

...took a 12 volt gel cell..connected..7 pin male end... nothing but a small spark from the running lights.

This too indicates a dead short. Possibly related to the previous break away battery install anomaly.

Your tow vehicles dedicated trailer running light fuse is blown. It will keep blowing until the short is found. Using your extra battery, to test, is perfect. Saves a lot of fuses.

You probably already have this, but here's the cheat sheet that I use here in the shop.

Hope you get this figured out soon! 50's are coming this Sunday.

 

[sjb]

Thanks for the diagram - dug that up last night as well.

Yes, removed the new battery and did check the connections below. I did not see anything that looked suspect, but this is one area I need to dig in deeper.

I don't think my trucks fuse is blown. Otherwise when I test the trucks pins, the green or #3 as listed above would not be lit up in my tester when I check the female plug in on my truck, right?

Did you remove the newly installed break away battery to check the spaghetti connections below it? The reason, that I ask is you said..............

Since the break away battery is connected to only the brakes, this says something got crossed.
Also............

This too indicates a dead short. Possibly related to the previous break away battery install anomaly.

Your tow vehicles dedicated trailer running light fuse is blown. It will keep blowing until the short is found. Using your extra battery, to test, is perfect. Saves a lot of fuses.

You probably already have this, but here's the cheat sheet that I use here in the shop.

Hope you get this figured out soon! 50's are coming this Sunday.

 

[snowfish]

I don't think my trucks fuse is blown. Otherwise when I test the trucks pins, the green or #3 as listed above would not be lit up in my tester when I check the female plug in on my truck, right?

Correct. I would have figured this scenario would have taken out the fuse right away. Unless, when you test the trailer end, you touched the wrong pin with the gel cell battery.

The trailer end is a mirror image of the tow vehicle. On the tow vehicle, the #3 running lights are at 11 o'clock. Looking at the trailer end makes that 1 o'clock. Easy to confuse. You may have touched the #4 charging circuit pin when testing the trailer. That would explain the spark.

 

[jmvette427]

sjb : the running lamps are in parallel. so if one goes out the rest will work . you said that you powered up running lamps at the first lamp and they worked that makes the high resistance / open circuit between that lamp and the plug . look inside frame rails pull the collar back on the plug make sure wire (should be brown) did not pull out of connector . also check the white wire thats the ground . worse case scenario fish a new wire from the lamp you tested back to the front .find the corroded wire !!

 

[yoopermike]

Do you by chance have grounds from each light to the trailer? I have a simple setup, open 2 place. I had the bulb fade going on for a while...then one went out...then both. I didn't realize I had a separate ground from each light to the trailer frame. Re-did those and voila.

Another thing, again if you have a GM, I had the internal ground, inside the male end on the truck side go bad/corroded on my 07 silverado. You can take this whole assembly apart. Can't remember exactly how now, it's been a few years, but when I did take it all completely apart, there was one spade or pin connector that was completely green. Sanded it, di-electric grease, then good to go.

Last thing I've tried, and it has worked on occasion, try sanding or wire-wheeling your balls. I mean ball on your hitch. With a rusty ball, it sometimes, for me anyways, worked intermittently.

 

[sw_lower]

check for a ground wire under trailer, ground to frame... salt eats wire..

 

[sjb]

Truck is a 2012 Ford F150

 

[tyeeman]

I have an enclosed aluminum trailer as well. 2 years after we bought it the marker lights on 1/2 of one side of the trailer quite working. Took it to the dealer and said fix it, , turns out it was one of those worthless crimp on connectors that let loose. Sure wish they could solder the joints or use a much better crimp connector. I know they cant solder the joints just from a time constraint stand point, but man would that be nice.
So essentially they had to open up a panel where the wall meets the roof of the trailer, and that's where the bad connector was.