I have a dumb little problem that I cannot find. I have lost 12V to the trailer connector at the back so I cannot charge my trailer batteries when traveling. Checked the fuses and took the connector apart at the back to make sure everything was together and making contact.


Any suggestions?

Get a long wire and hook it to the back. Pull the fuse and ohm the cold side to the fuse. You should read a short. If not, you problem is between those 2 points. (In theory anyway.)

Did you ohm the fuse as well, or just look at it? They can fool you occasionally.

Yes, I did run my meter across the fuses. Not exactly sure which fuse it is though. GM uses some acronyms that are a little confusing at times. Will try the long wire trick.

What year of truck?

2004.5 LLYEdited by: kodydog

SHould be simple. Has it ever worked?
Chances are you need to put a fuse where the red circle is. It comes with a shunt from the factory.


http://www.dieselplace.com/forum/uploads/ZC1_fuse.jpg

Yes I had the same problem, there needs to be a fuse as mentioned above. The fuse is supplied in the wiring harness that came with your truck it was that folded up piece of wires with the 6 into 4 connector taped to it . The fuse is located under the white sticker that is wrapped around those wires. place that fuse into the fuse panel as mention above and you should be all right.


I also had trouble w/ my trailer brakes when I swaped by brake controller from my 02 gmc to this rig. The mechanic at the rv dealer said that they moved on of the wires on the 04's and that was why when I applied the brakes they didn't work. The brakes only worked if I pressed the deadmans switch only. After he changed the wire in the harness they worked fine.If anyone has this problem I suggest talking to your rv mechanic he should know what the problem is.


JLewhttp://www.dieselplace.com/forum/smileys/Cool.gif

In the fuse position that you have circled Max Power, my fuse pannel has a red pass thru shunt. So maybe there is a fuseable link somewhere in the line back to the trailer connector as screaminjlew has indicated. This was working up until the last couple of days. My electric trailer brakes work fine. Just the charge circuit.


http://www.dieselplace.com/forum/uploads/827_IMG_0157.JPG

I doubt your charge circuit ever worked. Replace the shunt with a fuse and it will work. Try it, trust me. Steel a fuse out of the other locations for testing purposes if you don't have one handy.

Well I will be ....


I guess it was never working as that puts 12 volts back to the trailer connector. I took the 40 AM blower fuse and put it in place of the red plug which is obviously not a shunt.


I have a 110watt solar pannel on the trailer that must have been doing a good job while I was driving. I never watched it that closely before as I always found the batteries were fully charged when we stopped for the night. But the last couple of days have been very rainy so the light has not been all that good and we parked under some trees.


So that raises two questions, why was that fuse not installed in the first place and second is what size rating should I install?


Thanks Maxpower!!

Now that I re-read both of your postings, Maxpower and screaminjlew, I now understand. I found my original wiring harness which has the fuse taped under the white sticker, a 40 Amp.


I feel like a real dummy now.


I had been pulling the trailer with a 2002 GMC Denali XL and did not have the problem. So I assumed that the 2004 Chev Silverado would work the same.

They are never installed from the factory. I assume that a lot of people don't use this so they don't put it in to prevent corrosion in the back plug.


30 amp should be find. Of course if your batter is dead on the camper and you plug it in it could blow the fuse.

interesting to know. i have swaped my brake controller from my 02 avalanche 2500 to my 04 dmax and didn't notice. but i will check it out as i tow a 31ft coachmen tt at about 10K lbs dry. any other insite on this would be greatly appreciated.





Yes I had the same problem, there needs to be a fuse as mentioned above. The fuse is supplied in the wiring harness that came with your truck it was that folded up piece of wires with the 6 into 4 connector taped to it . The fuse is located under the white sticker that is wrapped around those wires. place that fuse into the fuse panel as mention above and you should be all right.


I also had trouble w/ my trailer brakes when I swaped by brake controller from my 02 gmc to this rig. The mechanic at the rv dealer said that they moved on of the wires on the 04's and that was why when I applied the brakes they didn't work. The brakes only worked if I pressed the deadmans switch only. After he changed the wire in the harness they worked fine.If anyone has this problem I suggest talking to your rv mechanic he should know what the problem is.


JLewhttp://www.dieselplace.com/forum/smileys/Cool.gif

So that raises two questions, why was that fuse not installed in the first place and second is what size rating should I install?


Thanks Maxpower!! The general does not install the fuse so that we have easy questions to answer here on the place :D The fuse tapped in my trailer wiring harness is 40 AMP.

Jim

NCMIC
I had to do the same thing when I swapped out my brake controller from my '02. Guess they changed the wireing :eek:
I will have to make sure I swapped the fuse tho, forgot to check that one.

look here for the wiring change:

http://www.tekonsha.com/files/Product%20Bulletin%20-%2020020013.pdf

upon looking at the 2 different connectors, the blue and brown wires were in different locations on the 02 than the 04. according to tekonsha, the change went into effect in 03. i will check mine when i get back to town as i had changed my connections.

The truck may be capable of 40A, but a lot of trailers seem to recommend a 30A for the trailers protection.
Verify what your trailer wiring is capable of.

Thanks guys, I had the same problem. Thought something was funny but couldn't figure it out. In my old truck the voltage would change if the house batteries were low. But in my new truck I didn't notice any fluctuation. I bought new batteries last spring and that masked this issue.
BTW I have coupled two six volt 220 Amp/Hr batteries together in series and found this quite a good set-up. Can't wait to tow again see how the batteries fair. I know I need to get al life. It's all fun....Thanks again for the great pix and directions.

MW:cool2:

Can anybody tell me which fuse it is in the 02. I am having the same problem.

It is strange why GM does what it does. I had the same issue with my brakes from my '02, but luckily my RV mechanic told me about it before I had to tow. As for that 12v fuse for the trailer, mine was actually in when I took delivery of it. I would highly doubt that the dealer did it but who knows :confused: . The spare was also attached to the harness!

D/A Power
Dose anyone know which fuse it is in the 02?
I thought my trailer was getting power last summer but when my trailer batteries ran down last fall, I hooked the truck up to the trailer and got nothing. I originally thought it was a problem with in the trailer. I had it checked and they say the trailer is fine.
I used a volt meter to check the plug on the truck and there is no power to the first pin clockwise from the key. I assume I must have blown a fuse. If someone could help point me to the correct fuse it will save me a lot of time looking for it. Thanks

D/A Power
Dose anyone know which fuse it is in the 02?
I thought my trailer was getting power last summer but when my trailer batteries ran down last fall, I hooked the truck up to the trailer and got nothing. I originally thought it was a problem with in the trailer. I had it checked and they say the trailer is fine.
I used a volt meter to check the plug on the truck and there is no power to the first pin clockwise from the key. I assume I must have blown a fuse. If someone could help point me to the correct fuse it will save me a lot of time looking for it. Thanks

I had an '02 gasser, and the trailer 12v fuse was located behind the auxillary battery on the passenger side. I was told that it was different than the diesels, but worth a look. The dealer did not even know it was there and had to look up the wiring schematic using my VIN.

It was a 'bolt-in' 40A fuse about 2-3 inches long with a hole on either end. If its not there, I believe it would have to be in the underhood fuse box.

Hope it helps! Let me know!

Thanks D/A.
I had looked for that bolt in fuse you previously mentioned and couldn't find it. The only fuse I thought it might be was stud 2 but it looked OK.
I did another search and found a line in another thread that said the 02 D/A should have a 30 amp in the Stud 1 location. My Stud 1 does not have a fuse in it. I will try it when I get home. I may never have had the power working.
I will let you know if it works.
Why would GM not put this fuse in?

I guess I never had power to the trailer last summer. I put a fuse in the empty stud #1 socket and now have power. Thanks D/A Power for your help.

I guess I never had power to the trailer last summer. I put a fuse in the empty stud #1 socket and now have power. Thanks D/A Power for your help.

No problem, glad to try to help! So many have helped me and its just nice to try to do the same when you can. Glad you got it working :) .