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Power Wire To 7 Pin Trailer Harness

bkgc5

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bkgc5 Enthusiast

bkgc5

Posted
Posted

I have searched the truch for blown fuze for the pwr wire that feeds the 7 pin trailer connecter . Has anyone had this problem and know why im not getting pwr to this hitch connector? Please help ...

old dog Enthusiast

old dog

Posted
Posted
I have searched the truch for blown fuze for the pwr wire that feeds the 7 pin trailer connecter . Has anyone had this problem and know why im not getting pwr to this hitch connector? Please help ...

 

did it work before ? have you looked under the hood for the fuse ? should tell wich one it is in the owner's manual .

bkgc5 Enthusiast

bkgc5

Posted
  • Author
Posted
I have searched the truch for blown fuze for the pwr wire that feeds the 7 pin trailer connecter . Has anyone had this problem and know why im not getting pwr to this hitch connector? Please help ...

 

did it work before ? have you looked under the hood for the fuse ? should tell wich one it is in the owner's manual .

 

 

 

yeah that was the first place I looked all fuzes are good and no empty spots ??? looked in the owners manual and that was the most vague ,How to plug in a harness but nothing specific

old dog Enthusiast

old dog

Posted
Posted
I have searched the truch for blown fuze for the pwr wire that feeds the 7 pin trailer connecter . Has anyone had this problem and know why im not getting pwr to this hitch connector? Please help ...

 

did it work before ? have you looked under the hood for the fuse ? should tell wich one it is in the owner's manual .

 

 

 

yeah that was the first place I looked all fuzes are good and no empty spots ??? looked in the owners manual and that was the most vague ,How to plug in a harness but nothing specific

 

i guess i should have been more specific ,this is a factory hitch and 7 wire plug ? it did work before ? you found the correct fuse ,and tested it with a test light to see if power was going through it ?you tested the 7 wire plug terminal for 12 volts? or is the trailer just not charging ?if not a factory plug there could be corrosion in the plug .or the battery break away and or charger or battery could be at falt .

steiny93 Enthusiast

steiny93

Posted
Posted

are you referring to the 30amp power line in the 7 wire?

 

if you mean the 30 amp power line you need to check the large 30amp fuse in the box under the hood. Its called stud #1 or stud #2 I believe. If you are not certain you had power their before you may need to go get a fuse as they were not installed from the factory. Owners manual calls it 'trailer power' i believe

bkgc5 Enthusiast

bkgc5

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Posted

ok , I have a 2004 3500 diesel the truck is equiped with two Batterys , according to the manual stud 1 is not used with this vehicle because it has dual batts (tp2) . Have owned the truck since new and im not aware that this 12 volt source has ever  worked ? I checked the stud 2 30 amp fuze and it tests Good ..And checked the plug  and no power . Im thinking the stud 1 that has a blank in the position pwrs this application but I dont want to Fry something based on the manual saying not to install this fuze ????  Ive been to my local dealer and they give me the deer in headlight look .

mljenkins Enthusiast

mljenkins

Posted
Posted
ok , I have a 2004 3500 diesel the truck is equiped with two Batterys , according to the manual stud 1 is not used with this vehicle because it has dual batts (tp2) . Have owned the truck since new and im not aware that this 12 volt source has ever worked ? I checked the stud 2 30 amp fuze and it tests Good ..And checked the plug and no power . Im thinking the stud 1 that has a blank in the position pwrs this application but I dont want to Fry something based on the manual saying not to install this fuze ???? Ive been to my local dealer and they give me the deer in headlight look .

 

Some trailers have the wiring in the plug reversed between aux and brake. If that was the case your brakes would stay on when you connected the trailer harness to your truck.

 

Have you run a meter across aux and ground on the rear trailer wiring harness to make sure there is definitely no 12V there?

 

When you say you have no 12V, do you mean you have no lights and/or brake either? Or is it just the aux that is broken?

bkgc5 Enthusiast

bkgc5

Posted
  • Author
Posted
ok , I have a 2004 3500 diesel the truck is equiped with two Batterys , according to the manual stud 1 is not used with this vehicle because it has dual batts (tp2) . Have owned the truck since new and im not aware that this 12 volt source has ever worked ? I checked the stud 2 30 amp fuze and it tests Good ..And checked the plug and no power . Im thinking the stud 1 that has a blank in the position pwrs this application but I dont want to Fry something based on the manual saying not to install this fuze ???? Ive been to my local dealer and they give me the deer in headlight look .

 

Some trailers have the wiring in the plug reversed between aux and brake. If that was the case your brakes would stay on when you connected the trailer harness to your truck.

 

Have you run a meter across aux and ground on the rear trailer wiring harness to make sure there is definitely no 12V there?

 

When you say you have no 12V, do you mean you have no lights and/or brake either? Or is it just the aux that is broken?

 

 

 

no I have lights and brake its just the aux that is not working , within that harness you have 3 large guage wires com ground, blue brake control and red main pwr . that main power is dead

Bluedog Enthusiast

Bluedog

Posted
Posted

You need a real fuse in the Stud 1 spot. From the factory it was a plastic dummy. If so, put a 30A fuse in that spot and it should work. That is all you need to do to hook it up. If you are not getting power to the pin, with the fuse in place, then you have an electrical problem - likely in the plug itself. That is the correct fuse, you won't fry anything.

 

HTH

bkgc5 Enthusiast

bkgc5

Posted
  • Author
Posted
You need a real fuse in the Stud 1 spot. From the factory it was a plastic dummy. If so, put a 30A fuse in that spot and it should work. That is all you need to do to hook it up. If you are not getting power to the pin, with the fuse in place, then you have an electrical problem - likely in the plug itself. That is the correct fuse, you won't fry anything.

 

HTH

 

 

bluedog

my truck does have that dummy plastic fuse , but the manual says its not to be used if the truck has two batts ???

Bluedog Enthusiast

Bluedog

Posted
Posted
You need a real fuse in the Stud 1 spot. From the factory it was a plastic dummy. If so, put a 30A fuse in that spot and it should work. That is all you need to do to hook it up. If you are not getting power to the pin, with the fuse in place, then you have an electrical problem - likely in the plug itself. That is the correct fuse, you won't fry anything.

 

HTH

 

 

bluedog

my truck does have that dummy plastic fuse , but the manual says its not to be used if the truck has two batts ???

 

 

Manual is not correct for diesels - it is referring to gas engine trucks with the dual battery option. It will work - did in my 2000, 2003 and 2006... the 2008 is a different story.

  • 1 month later...
HawkScot Enthusiast

HawkScot

Posted
Posted

Basic troubleshooting.

 

1) if the manual says that fuse in not used in dual battery setups, then that would mean that the second battery is supplying the power to the trailer wire (and that it is isolated from the first battery by a relay that is only closed when key is on). There should be a smaller wire (perhaps 8 or 10 gauge, not the very large battery cable) coming from the second battery (or perhaps near the relay). There should be a fuse somewhere in that line between the battery and back bumper.

 

2) my guess is that it was never hooked up. My 2008 Yukon XL had both the trailer charge wire and trailer brake wire taped up to the harness under the hood, but did have the fuses installed. I charge my trailer battery fine, but have to be careful to disconnect the trailer plug from Yukon so it doesn't run the Yukon battery dead when parked.

 

Trace any wires coming from the positive terminal on the second battery. You should find the trailer wire connected to that leg somewhere. I doubt that you will. Then try and find the trailer wire (this is harder since it is usually buried in a wire bundle). I really think you will find a loose end that needs connecting. My 2008 was simple, it connected to the stud in the fuse box under the hood, right were the directions said. Yours will be more difficult since you will want it to connect to your second battery probably.

 

Now, some thoughts. On my older pickup, we had a second battery under the hood (and the isolator stuff) so that our truck camper had 12V. There was not a battery in the camper, it used the one under the hood. I thought about installing a second battery in the Yukon and moving the wire for the trailer connector over to it, but what is the advantage? I already have two batteries in the trailer. I only need the Yukon for a charging circuit occasionally.

 

How is your second battery used? How do you want it to be used?

 

Good luck.

BlackSilver Senior Enthusiast

BlackSilver

Posted
Posted
You need a real fuse in the Stud 1 spot. From the factory it was a plastic dummy. If so, put a 30A fuse in that spot and it should work. That is all you need to do to hook it up. If you are not getting power to the pin, with the fuse in place, then you have an electrical problem - likely in the plug itself. That is the correct fuse, you won't fry anything.

 

HTH

 

 

bluedog

my truck does have that dummy plastic fuse , but the manual says its not to be used if the truck has two batts ???

 

 

I'm presuming your truck is a DuraMax. Put a fuse in "Stud 1".

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