Chevy Trailer Fuses

[tunaman]

My trailer running (marker) lights went out, but the turn and stop lights work fine. I've checked both fuse boxes several times, and when Obi was up we both checked thoroughly and couldn't find anything remotely appearing to be for them... anyone know which fuse label is for them?

It's a 2005 Tahoe, but I'm sure many models have the same fuse arrangements. I've searched the web several times, but haven't turned up any good links, so any input is appreciated.

Roger

[Garrett Mercer]

Roger,

Not sure if you use one, but I had the same issue with my F-250 and my boat trailer, and it turned out to be my 7 round to 5 flat adapter that went bad.... Again, probably not the issue, but might be worth checking....

Garrett

[tunaman]

Thanks Garrett... I tried another adapter that I have for my motorcycle trailer, but they were still out. Thanks for the suggestion though!

Roger

[DeltaBound]

Roger, try cleaning off your hitch ball, it's probably not grounding correctly.

[tunaman]

Thanks... thought about that, but with the other lights working fine it doesn't make sense. I'll try it anyway, just to eliminate any possibilities - needs a fresh coat of grease anyway. Thanks!

Roger

[DeltaBound]

The same thing happened to me and cleaning the ball hitch worked for me.

[scottsweet]

Have you put a meter on the pins without the trailer to verify you are not getting power to the connector?

This will isolate whether it is the trailer or the truck.

Scott

[Obi-Hub]

Have you put a meter on the pins without the trailer to verify you are not getting power to the connector?

This will isolate whether it is the trailer or the truck.

Scott

I did this for Tunadude when I was up thar for da house warmin'. No power coming through the Brake pin on the trucks Seven Pin. Power on all the other appropriate pins.

On a similar note, I have the same problem with Accessory power connector on that dash that also goes to the trailor. I was running our fish tanks filters off it for a couple of hours when the power transformer up the street from our offices and made the mistake of plugging in my laptop and "popped" the circuit in the truck ('05 Avalanche). I have pulled every fuse on both the dash and engine compartment fuse panel to try to find it and no joy

Obi

[tunaman]

Thanks for the additional input guys.

For further input, this seemed to begin when I rented a U-haul trailer during our move... the boat trailer lighting was working fine last time the boat was hitched up, so I suspect the wiring on the U-Haul was faulty and took out the fuse... can't validate since I can't find the d@mn thing!

The other complication is that, since we moved, all my tools are still boxed up in the garage... have to dig through to see if I can find my DVM or one of the many test lights I own!

I'll check the suggestions that I haven't tried yet, just to eliminate them, so thanks again for the input! Still looking for someone who knows what the stupid label is, though!

Roger

[tunaman]

Come to think of it, I guess I can run a jumper to the running light connector from the brake or turn connectors just to validate that the trailer lights aren't FUBAR... that would eliminate the trailer anyway.

Roger

[scottsweet]

You have your owners manual? This info would be in there.

[tunaman]

Thanks Scott... yeah, it's around here in a box somewhere!!! I've checked the online manuals, though, and the owner's manual doesn't get into detail, rather shows the location of the fuse blocks... I already know where they are, so that isn't very helpful!

Roger

[tunaman]

Yet another reason to support your local dealers... called the dealer I bought it from (Selman Chevrolet) on their toll-free line, and a service person looked it up and gave me the information. I've searched off and on for the last couple of weeks via Google, but couldn't find it.

For reference, the trailer marker lights are fed off a fuse in the under-hood block appropriately titled "Stud #2" - sheesh! It's not a blade fuse, is 30 amp, and from inspection it does appear that it may be blown... now to dig up a DVM or test light!

Thanks to all for your input! Happy Thanksgiving to all!!!

Roger

[tunaman]

Well, finally was able to do some more troubleshooting, and looks like I may have to take it in...

I was able to find a DMM (THANKS WON BASS - I had the meter that I got two years ago at the US Open in my boat! ) and checked the fuse... while it looked like it was open, it actually has continuity.

I rang out the adapter, and found that all of the pins had proper connectivity.

I jumped the turn signal to the running lights, and they were fine.

This eliminated everything from the hitch on back...

Haven't been able to find a wiring diagram, so not sure about the circuit... visual inspection of the connector and the wiring reveals nothing amiss, so if I can't find an online diagram I guess it is off to a dealer or other qualified savior.

Roger

[trailersource]

I would almost guarantee you it's your running light fuse, which should be under your hood in the fuse panel right in front of the driver's seat. I believe the running light fuse on an 05 tahoe is a ten amp fuse underneath the upper left fuse block. there should be three 10 amp fuses in a horizontal row and I believe the running light fuse is the furthest left when looking at it. Most likely the U-haul trailer had bad wiring which blew your running light fuse. Very common. You can get a cheap power emulator to plug into your seven round on the back and test running lights, turn signals, brakes, etc. to see if power is to the plug, but more likely than not it is the running light fuse. I could be totally wrong but I deal with trailer on a daily basis.

[Ron C]

I had a similar situation a number of years ago and it ended up being a short in the running light wire (as I also call it Roger). In a very hard to find (and reach) spot, the wire had a cut in it and was grounding out against the trailer frame. A little electrical tape did the trick.

Not sure if yours is the same problem, but it's worth a look. By the way, the short never did blow the fuse - it just prevented the running lights from working.

Ron C

[tunaman]

Thanks to you both for the additional input, and I'll take another look tomorrow and focus on those two areas... it was raining lightly today when I worked on it, so I didn't pursue chasing the wiring loom all the way along the frame.

As far as fuses go, I'll check it out again and pull each and every one if necessary, now that I have my DMM, but according to the service man (and the diagram I found on another site, Stud #2 is used for the trailer lighting (and the stop and turn fuses are clearly labeled oddly enough).

Thanks guys, and have a very happy Thanksgiving!!!

Roger

[Murph]

Hey Roger, this might have been mentioned, above somewhere. But! Do not rely on your Ball for the trailer ground! If your plug doesn't have a white wire running to the front of the hitch somewhere, put one on.

[tunaman]

Thanks Murph... this is factory wiring, and does indeed have a dedicated ground wire. I've verified that the ground is intact, and that the ground on the adapter and trailer are also solid. Thanks for the additional input though - appreciate it! Hope you're having a wonderful Thanksgiving!

Roger

[Ron C]

Do not rely on your Ball for the trailer ground! If your plug doesn't have a white wire running to the front of the hitch somewhere, put one on.

That's some great info right there Murph. I learned that one the hard way a long time ago.

[L.Mickelson]

When mine was grounding out in the same fashion it was one of my license plate lights. It was burnt out and every time I hooked up the trailer it would short the running lights. Don't know why all I know is once I replaced the bulb the problem went away

[macinckirk]

I would almost guarantee you it's your running light fuse, which should be under your hood in the fuse panel right in front of the driver's seat. I believe the running light fuse on an 05 tahoe is a ten amp fuse underneath the upper left fuse block. there should be three 10 amp fuses in a horizontal row and I believe the running light fuse is the furthest left when looking at it. Most likely the U-haul trailer had bad wiring which blew your running light fuse. Very common. You can get a cheap power emulator to plug into your seven round on the back and test running lights, turn signals, brakes, etc. to see if power is to the plug, but more likely than not it is the running light fuse. I could be totally wrong but I deal with trailer on a daily basis.

I'll 2nd this I had this happen a few times on my 95 gmc van with the last trailer before I rewired it, i had a small bare spot on a wire in the trailer that was for the running lights and sometimes it would hit the trailer frame and pop the fuse under the hood, I would have tail, brake and back up lights but no running lights.

Should of said something when I was there, I could of shown you the fuse in 5 secs. It is a 10 amp blade fuse right where this guy says it is

if need be R take a pic of the fuse box under the hood and e-mail me it and I'll mark the 1

[macinckirk]

Now that I was out getting ready to go fishing and thinking about this, R I would hate to have you take the time to take a pic. maybe it would be best if I come up and help you find the fuse in person you know anything to help a buddy out

LMAO

[tunaman]

Can you be here in 10 minutes??? I'm just getting ready to head out...

I'll pull each fuse and check them by hand - pretty much gotta be the issue. Found that the Right Turn/Stop was blown (funny, the right-side stop and turn lights on the trailer still worked???) and thought for sure that was the issue, but when I replaced it I still had no running lights. Rechecked the new fuse and it was still fine, and had no more time to continue searching. I'll see if I can finish today after I get off the water.

Thanks all again! Hope everyone had lots of Thanksgiving goodies to fill their bellies yesterday!

Roger