Truck & trailer wiring

[x.system]

Wiring is not one of my strong points but I can do the basics. I'm having a wierd problem with my 02 gmc 7 pin connector. I pulled the old one off because it wasn't working and have the new one almost on and wired up. The problem is I am not getting my right blinker and brake light to work on the trailer. I've got running lights and my left side brake and blinker. I've been probing around with a test light and I can get the right brake light at the plug but no right blinker at all. any ideas?

[cybrman]

My memory isn't always the best and its been awhile but I have 2 boat trailers and seem to recall 2 bulbs. The larger one had 2 wires/circuits for brakes/turn signals and running lights, the other was just running light with only 1 wire/circuit.
I would check the large bulb with 2 wires and make sure both are good and then check the bulb itself to make sure both filaments are good.
Hope this helps

Another thought...
Check the connector itself it is very common for them to get corroded or the bottom of the bulb corroded.

[Jason Hall]

Check the ground. Is the light mounted In rubber? Or Is It bolted to a steel bracket? Nothing works without a ground, so If you have power make sure the ground Is good. You can use your test light backward to check the ground. Hook the clamp end to something hot (12 volts) then prob the ground, and If It's good you light will light.

Did you get all the wires In the correct spots when you changed the end?

[Mosh]

Here is a schematic from all data.

Let me know if you need more.
I looked it up for a 2002 GMC K 1500 4wd.

They make plug in inline conectors for those at Napa for about 30 bucks.
Plug and play..well worth the money.

Looking at the schematic, you may have popped a fuse.
Check the big box near the battery to see if any are blown.

[x.system]

Check the ground. Is the light mounted In rubber? Or Is It bolted to a steel bracket? Nothing works without a ground, so If you have power make sure the ground Is good. You can use your test light backward to check the ground. Hook the clamp end to something hot (12 volts) then prob the ground, and If It's good you light will light.

Did you get all the wires In the correct spots when you changed the end?

My main problem is at the truck plug right now, not worried about the trailer but the plug was not wired correct in the first place so I started from scratch.

I did the reverse and checked ground. The main problem is I know what wire controls the right blinker/brake light but when I test it at the plug it just lights solid on the test light with the blinker going. The left will blink on the test light with the blinker on, I can't seem to figure out why the right isn't doing the same.


Mosh, thanks, I didn't know there were more fuses other than in the cab, I will check those in the morning. My first plan was to buy the plug and play but someone had already cut off the end needed to do that. I was actually at the store and went back out to check fitment and noticed that is was gone. If I can't get it tomorrow I'm going to see if I can replace the tail end of the harness and get that inline connector.

I will get it figured out tomorrow.