No 12 V + at factory 7 way

[4sight]

I have a 2002 2500 ext cab with the factory trailer harness. There is no power coming out of the 12v+ tab. I can not find a fuse or relay to control this. The trailer fuse and relay are fine. My 2004. 5 3500 has a fuse in the junction box. The trailer wiring and brakes all work fine except for this. I need it to keep the break-a-way battery charged.



I didn't buy the truck new so I am not sure if this was ever operational. I know on Chebbies and Ferds the fuse needs to be added to the junction box. Maybe the same case here or a wire tied in that is taped up some where waiting to be hooked up?



I know isolators should be used and all that, I am just looking for low amp source as it should work and be.



Thanks

 

[Hoefler]

Are you checking it with the ignition on?? If so, check the connection behind the plug. It may not have the the wiring from the factory, it could have been installed after market using the factory harness, is it hooked up underneath??

 

[4sight]

I did check it with ignition on and running even though its the same position on switch. It definately has the factory wiring and hitch. Everything is hooked up/plugged in. I have all the original paper work and window sticker showing factory tow package. I am still hoping it is something simple and not a matter of pulling wire out of the loom and tracing for a break. I can't be the only one :{

 

[jelag]

My trucks have a fuse in the panel that provides power to this connection..... are you sure that fuse is good.....

I've had trouble keeping the batteries on my 5er charged so I ran an 8 gauge wire from the battery to the that connection as well as an 8 gauge wire to ground from the ground terminal on that connector as well... (with 30 amp fuse) This one thing changed the available voltage at the trailer by 1 volt... .

Hope this helps.

 

[jkidd]

if you have ever had a 5th wheel installed with splicing into the wiring it is real easy for the wires to get corroded.

 

[MLee]

These wires in my wiring harnes were little 18 gadge. So I ran a 10 to the rear and put a auto relay breaker in the line, instead of a fuse. Do it you'll be happier. Also do a larger Ground wire while your at it and run it to the battety. These truck have poor ground wiring.

 

[4sight]

Every fuse is good both under hood and dash. No splicing has been done. There isn't any corrosion at the plug. I just had it apart to add a T for in bed wiring.



I know it would be better to run a bigger guage wire to charge camper batts. but I don't need it for this application. Just a few amps is all I need. I like to keep everything OE if possible. Looks like I am going to be tracing from back to front.

 

[jelag]

jkidd has a great point... my NEW 5er was full of scotch lock connectors... I spent 3 days looking at all the connections, taking them apart and used non insulated butt connectors and heat shrink tubing that well installers use...

The heat shrink tubing has a adhesive that melts with the heat gun and makes the connection water tight... . better connections and no moisture... .

 

[AClayton]

This is just a thought... after reading all the posts and determining the fuses good and such. My question is... How did you check for 12V at plug?You may have 12V at #4 terminal but no ground at GRD term. which will give false reading to you on your meter. Check #4 term. on plug with a known and confirmed GRD source. This has happened to me before and I thought I would present to you before you tear into your harness searching for a loose or bad connection. Please understand that I'm not insulting your intelligence by suggesting this if you had already ckd it ... . troubleshooting electrical problems can be quite frustrating at times and sometimes the easiest things can be overlooked.