PDA

View Full Version : trailer light not working...Help please!!!


Linder'sLawnCare
04-23-2009, 09:15 PM
I have a 02 gmc sierra 1500 z71... I am having a problem with one of my trailer lights. I just got done trying to fix it for the last hour... anyway, the left tail light only the running light comes on. it does not come on when i hit the breaks and the blinker. I put a new bulb in it too. it is the second trailer i had this problem on. it has to be my truck. i know i am not the only one that has had this problem. Thanks!!!

jrandallb
04-23-2009, 09:21 PM
I had the same problem, there is a seperate fuse for the left and right trailer lights.

Coastal Lawn Maintenance
04-23-2009, 09:24 PM
check your fuse box you probable have a blown fuse. if not that one of the wires that runs to your plug has gone bad

Horsepower Lawns
04-23-2009, 09:33 PM
The fuse box is under the hood or on the side of the dash.
If its on the dash, open the drivers door and look at the end of the dash.
Left & Right have different fuses no matter where its at.

Linder'sLawnCare
04-23-2009, 09:41 PM
I have a fuse box under the hood and in my truck let me go see what i find out

meets1
04-23-2009, 09:42 PM
I feel your pain. Although i have the opposite. On my 97,02,03 trucks - everything works with all trailers I hook up to the 07,08,09 new model GMC trucks - just like that blow fuss. All I ever have is brake and turning signals - no running lights at nite or lic. plate light - don't get.

Linder'sLawnCare
04-23-2009, 09:51 PM
ok. I only have one fuse for all my turn signals. and it is still good. wish it was a bad fuse

topsites
04-23-2009, 09:52 PM
After countless hours of frustrating myself with this exact nonsense I found the EASY solution.
Because it just doesn't matter, trailer lights will fail, sooner or later, sometimes several times in a short period of time.

Obviously you'll need the specific adapter for your trailer's connector,
but get one of these with the LED test lights, then you always can troubleshoot
on the spot whether the source of the problem is in the truck or in the trailer.

Whether you tap the brakes, the turn signal (either one) or the running lights,
as power hits the adapter the LED that goes to the wire carrying the electricity lights up,
so you instantly know what color even if your trailer is wired with the wrong colors you will
know which one to fix because the LED lines up with the wire.

Then if the LED doesn't light at all, the problem is in your truck.
Don't gotta unhook or start guessing squat, just watch the LED's.

They cost about the same as a regular adapter, certain auto parts stores tend to carry it.

In this picture below, the lighted LED is pointing to the SECOND wire from the bottom, it also tells me
that wire is getting juice, so if the light isn't coming on then the problem is between the connector and the light,
worst case scenario if I have to replace the entire length of wire at least I already know which one.

Linder'sLawnCare
04-23-2009, 09:53 PM
I feel your pain. Although i have the opposite. On my 97,02,03 trucks - everything works with all trailers I hook up to the 07,08,09 new model GMC trucks - just like that blow fuss. All I ever have is brake and turning signals - no running lights at nite or lic. plate light - don't get.

is it a GM thing. if it is, then it is my first complaint with GM (besides its economical situation:laugh:)

Linder'sLawnCare
04-23-2009, 09:55 PM
Obviously you'll need the specific adapter for your trailer's connector,
but get one of these with the LED test light, then you always can troubleshoot
easily whether the source of the problem is in the truck or in the trailer.

The LED even points to the responsible wire, so you instantly know what color
even if your trailer is wired with the wrong colors you will know which one to fix.

(They cost about the same as a regular adapter, certain auto parts stores tend to carry it).

I have one and it reads my right blinker and my running lights but not my left blinker. Thanks for the advice though. And i have the right connector going into my truck

4.3mudder
04-23-2009, 10:08 PM
If the fuse was blown, the brake light would be on all the time when the parking lights are on. I'm assuming a safety thing when a fuse pops, the light stays on like that. Mine did that when a fuse went out due to a short. mine is a 2004 silverado.

So, you have the connector with LED's and it is not showing up for the the brake/blinker?

4.3mudder
04-23-2009, 10:12 PM
Oh, I forgot to mention. My harness that went from the end of the truck to part way underneith, it is like maybe a foot long, has a female end on one side and male on the other. Those terminals get correded, I recently had to replace mine, filled with water, and it broke the parking light spade off when I disconnected. I was pissed, 22 bucks later all is good. I was getting good connection up until that connector, but after the harness it was corroded and did not work.

Linder'sLawnCare
04-23-2009, 10:18 PM
Oh, I forgot to mention. My harness that went from the end of the truck to part way underneith, it is like maybe a foot long, has a female end on one side and male on the other. Those terminals get correded, I recently had to replace mine, filled with water, and it broke the parking light spade off when I disconnected. I was pissed, 22 bucks later all is good. I was getting good connection up until that connector, but after the harness it was corroded and did not work.

Yes about the led adpater. At the end of my truck is a round plug female, no square female. I bought it used and just assumed that was stock, but based on what you are saying i am confused. Are you saying to look up under my truck and see if I have them terminal and if they are corroded or is you truck different? It has to be my truck not my trailers.

4.3mudder
04-23-2009, 10:26 PM
I guess it does not matter how yours is. Some have just a 7 prong, mine has the 6 round and 4 flat combined on the thing. This mounts up undernieth your bumper I think on the hitch, now, trace the wire under that truck, there should just be a foot of wire then a big connector. You can unplug it and check the connectors making sure they are tight and do not have corrosion. This is the problem that I ran into before on mine because of water.

4.3mudder
04-23-2009, 10:33 PM
This will be on the other end of the harness that you unplug

IdealLawnCare
04-23-2009, 10:36 PM
I would say isolate the problem to either the truck or trailer. Is there another truck you can hook the trailer to or another trailer to hook to the truck. That will tell you where the issue is. You can even run wires from a battery to your trailer and see if all the light work properly.

Linder'sLawnCare
04-23-2009, 10:42 PM
thanks 4.3mudder. i will look at it in the morning. i am thinking it is something like that. My hook up is a 6 prong, i think, next to my towing package. I did not look for the harness. I will post updates as soon as i can. I just hope that it is something simple

4.3mudder
04-23-2009, 10:46 PM
Ya, I don't know if it is the problem you are having.

But, just for the hell of it one day I was checking my lights and could not figure why parking lights and one side blinker would not work. Well, it was that plug on the harness all corroded. Water was actually sloshing inside.

But, when a fuse pops for the left or right side blinker, and the parking lights are on, the brake lights will stay on all the time. Factory safety thing I guess. Good luck.

Linder'sLawnCare
04-23-2009, 10:49 PM
4.3 mudder this is totally of subject but about your chevy(if automatic), when shifting from 1st to 2nd does it shift real firm and somewhat hard? mine does and all of my buddies that have same z71 does too. JW

4.3mudder
04-23-2009, 10:54 PM
Na, I think for me it is all the same. through all 3 gears and overdrive. What I can really tell is the drop in "peak power" when it shifts form 1st to 2nd when I'm pulling. But, mine has the 4.8 so power? not very much, but good enough for what I use it for. Now, on my 350 tranny in the toyota it has a shift kit, it will pop me back in my seat if not carefull. I like shift kits because everything is real tight, less slippage. Tranny doesn't wear out as quick.

Horsepower Lawns
04-23-2009, 10:57 PM
But, when a fuse pops for the left or right side blinker, and the parking lights are on, the brake lights will stay on all the time. Factory safety thing I guess. Good luck.

Thats not factory & sounds like a ground problem.

Keep looking for a blown fuse. Did the one you found say "trailer turn fuse"

4.3mudder
04-23-2009, 11:01 PM
Thats not factory & sounds like a ground problem.

Keep looking for a blown fuse. Did the one you found say "trailer turn fuse"

Na, all my stuff works. That is just what mine did one time. When the parking lights came on, the tailer brake lights stayed on all the time even when you put the signal on to whatever side fuse was blown. Parking lights off, the brake lights turned off. Replaced the turn signal fuse for whatever side it was and it was fine. I think it is a safety thing. For sure. It's a newer truck, so they might have added that to it.

Linder'sLawnCare
04-23-2009, 11:05 PM
it might be a 4wd deal? IDK

4.3mudder
04-23-2009, 11:10 PM
Maybe. usually heavier duty trucks have "shift kits" in them already. I would not say a shift kit, but anything to lock up the clutches inside quicker is better. I know my dad used to have an 03 1 ton, and it shifted very firm, because of towing you did not want it slipping when shifting. Burn up the tranny in a heartbeat.

Linder'sLawnCare
04-23-2009, 11:33 PM
Thats not factory & sounds like a ground problem.

Keep looking for a blown fuse. Did the one you found say "trailer turn fuse"

I only have one fuse for turn signals and it is fine. I am thinking loose conection or broken wire.

4.3mudder
04-23-2009, 11:39 PM
Hmm, I have 3 fuses. One for left turn/brake, 2nd for right turn/brake, and the other for parking lights. Parking light fuse is under the hood, other 2 are on the driver side dash next to the door.

Horsepower Lawns
04-24-2009, 09:10 PM
Na, all my stuff works. That is just what mine did one time. When the parking lights came on, the tailer brake lights stayed on all the time even when you put the signal on to whatever side fuse was blown. Parking lights off, the brake lights turned off. Replaced the turn signal fuse for whatever side it was and it was fine. I think it is a safety thing. For sure. It's a newer truck, so they might have added that to it.


I have been repairing trucks & trailers for 8-9 years full time. You have something strange going on. The only time something like that happens is when you don't have a good ground and it "steals" ground from somewhere else.

4.3mudder
04-24-2009, 09:12 PM
I have been repairing trucks & trailers for 8-9 years full time. You have something strange going on. The only time something like that happens is when you don't have a good ground and it "steals" ground from somewhere else.

I had a guy doing that on his ford pickup too, I think it was a 2000. Same ordeal, 2 new fuses and it was all good.

Linder'sLawnCare
04-25-2009, 12:07 AM
I have read through my manual and searched the fuse box and still no right and left turn signal. it is all the same. If it was a ground would it possibly be green because i do have a green wire dangling by my hook up and when i put the voltage meter on it it read nothing. yet all the other wires did. i will experiment with making that wire ground out and see what happens. this is becoming agrivating

4.3mudder
04-25-2009, 01:46 AM
I have read through my manual and searched the fuse box and still no right and left turn signal. it is all the same. If it was a ground would it possibly be green because i do have a green wire dangling by my hook up and when i put the voltage meter on it it read nothing. yet all the other wires did. i will experiment with making that wire ground out and see what happens. this is becoming agrivating

I think that your are probably so caught up in that pretty girl in your avatar that you are missing something. :hammerhead: lol just kiddin. So, they must have changed the fuse block then after your year model. I would try what you said and see what comes about. I can imagine it is getting aggravating.

Horsepower Lawns
04-25-2009, 08:44 AM
I have read through my manual and searched the fuse box and still no right and left turn signal. it is all the same. If it was a ground would it possibly be green because i do have a green wire dangling by my hook up and when i put the voltage meter on it it read nothing. yet all the other wires did. i will experiment with making that wire ground out and see what happens. this is becoming agrivating

Chevy uses light green for back up & dark green for right turn. Is the wire on the truck or trailer?

GravelyNut
04-25-2009, 07:43 PM
Here's something also to check. How many bulbs are in your taillight assemblies? If one of the top bulbs burns out in an assembly with the tiny bulb also, you can also lose the trailer turn signals for that side. Sounds dumb but ran into that on an 07 2500HD.

Linder'sLawnCare
04-26-2009, 08:28 PM
I fixed it. After all the time i put in checking wires and plugs, it was the fuse under my hood. I did not even look or think about it. I felt really humble after taking 5 seconds to change the fuse.

4.3mudder
04-26-2009, 08:32 PM
I fixed it. After all the time i put in checking wires and plugs, it was the fuse under my hood. I did not even look or think about it. I felt really humble after taking 5 seconds to change the fuse.

:hammerhead::hammerhead: Least you found it. lol

jk mow & more
04-28-2009, 10:20 AM
i have had problem too before it has been bad ground it is hard to keep a good ground with corrosion and weathering rusting check all grounding points clean them and coat them with scotchcote can be bought at electrical supply will help with corrosion of the connection:cool2: