EVRYTHING 12v Power at Trailer plug maxi fuse fuses

[avking]

No, it should be powered all the time.


Yeah, I would suppose that the trailer could back-feed the truck and drain the battery.

I would think that some kind of heavy duty rectifier should be on the trailer where the wire attaches to the battery so that it will allow power to flow into the trailer on that wire, but not back out. I would think that this would be a common problem, and such a part would be easy to find. Isn't there some sort of battery charger controller on the trailer? I would think that one of its functions would be to prevent that from happening.

Another think to check is for dirt/corrosion on the trailer battery, or somewhere in the wiring that could be causing a current leak to ground. Also check for any parasitic current draws in the trailer (accessories that are left on and always drawing power.)

Finally, it could just be that the battery is failing, so that it just can't take much of a charge or hold it for very long.

-- SS

I know the battery is good, because it does not loose juice until it is attached to the truck. If I charge it, and tow without hooking the wiring harness to the truck (short distance drive) I do not have the problem and the battery lasts all weekend. But attach it to the AV and it dies fast. I will look into your other instructions.

[RichUF]

I added a 12V outlet in the bed yesterday (also did a switch for bed lights  )

Couple of Q's...

1)  The maxi-fuse for stud #1...30A or 40A, or doesn't matter b/c there is an in-line 10A for the outlet?  Anything else I need to know about which fuse to get?

2)  I tapped the big fat red wire in the trailer harness.  I used a scotchlok, but am not particularly confident with this connections (scotchloks seem to work well for switches and small wires, but not this big fat power one)...any suggestions?  I don't particularly want to sever this wire.  wire is exposed, so maybe just solder and tape?

Thanks  

[OviedoAv]

Let me know when you figure it out. I did the scothlink thing also on mine , and it doesn't work

[RichUF]

Did you install the maxifuse and get a good ground?  I suspect the problem is the scotchlok is not contacting.  I'll know tonight after I confirm the correct fuse and buy it.

[ygmn]

Cut off some of the insulation.....wrap new wire around....solder....then wrap with good electrical tape....

that is how I added LOF....

[RichUF]

Cut off some of the insulation.....wrap new wire around....solder....then wrap with good electrical tape....

that is how I added LOF....

Yeah, that's what I figured.  Tried to do it the impatient, hack, easy way    Didn't make my wire runs real pretty underneath either...rather disapointed with myself.  Oh yeah, slipped with the hole saw on the plastic and marred a little too    Oh well.

[RichUF]

sorry, I did my usual of asking multiple questions and then talked right over it so the q's get burried  

for maxifuse...  30A, 40A, or doesn't matter?

TIA

never mind...found it in this thread already    

[FSHNGUY]

There is a dedicated wire on the 7 wire trailer plug at the rear that operates auxilary lighting such as lights inside a trailer. You need to have the dealer put a fuse in that spot in the box under the hood. I found this out when pulling a 28 foot enclosed trailer. It's either a 40 or 50 amp fuse required.

[ShapeShifter]

There is a dedicated wire on the 7 wire trailer plug at the rear that operates auxilary lighting such as lights inside a trailer. You need to have the dealer put a fuse in that spot in the box under the hood. I found this out when pulling a 28 foot enclosed trailer. It's either a 40 or 50 amp fuse required.

Underhood, "STUD 1", 40 amp: feeds unswitched B+ for battery charge and aux lighting.

This fuse is often not installed at the factory, and often has a red dummy fuse in its place. If you think it is already installed, look closely and make sure it is really a fuse.



There is another fuse that it is often confused with, one which is usually installed at the factory:

Underhood, "STUD 2", 30 amp: feeds electric trailer brake controller.

-- SS

[Rdrunr]

I have a slight problem with my 2004 Av. I hooked up the electric brake controller  last year, that works great. All of the signal lights on my 30' tow-behind work perfect also...Here's my problem...I would like to be able to plug my trailer into my Av with it running and get a charge back into the trailer battery when it gets low while camping. I tried this last summer but seems that it gets no charge when plugged into the Av while it's running or not running. The light were just as dim as when it wasn't plugged in, leaving me to believe that the connector in the plug that is suppose to deliver 12v to the camper battery must not have juice flowing to it.

Is it possible that I'm missing a fuse somewhere under the hood or dash? Please "dumb down" your responses...I make my living as a salesman, not a mechanic!

Thanks ahead of time for your valued responses! Rd

[sperry]

In THIS LINK is some info you could use for your fuse. It's usually missing!

Look at the second layout, as the first one is for 02's..

HTH!

[BLIZZARDICE]

So I have the 12volt supply all working but is this going to be always on? Or just when I have the ignition on. That last think I need is the trailer draining the truck battery!!!!

[Doug B]

 :help:I recently purchased a (mildly used ) '07 with towing package.  I've read all through this thread and I can't figure out how to get power to the trailer charging contact on the 7-pin connector.  The brake controller harness was already installed under the driver-side dash with factory taped pigtail ends .  Mine came with the 30A (position 66) brake power to stud 2 and the 40A (position 71) trailer charging power  to stud 1 J-case fuses already installed. I have confirmed that the fuses are good and both post 1 and post 2 both have +12V present when the engine is running.  The red/bk wire running from the under-hood center to the brake controller harness was not connected to stud 2; it was taped to the wiring harness.  I looked at a couple new trucks on the lot tonight and same thing.  When I connected it to stud 2 the trailer brakes work fine, but no charging power.

There is not a second wire for connection to stud 1 that I can find.  The Owner's manual would lead me to believe there should be a second wire waiting to be landed on stud 1.  There is a heavy gauge (10 or 8 AWG) red wire terminated in the 7-wire connector at the rear of the truck, but I can't locate the other end anywhere to save myself.

All other trailer light functions work fine using both 7 wire and 4 wire connectors

As expected, neither the dealer nor the Owner's manual were much help.  Has anyone else had and/or solved this problem yet?    Thanks !

[Doug B]

I just found the answer to my last post under another thread "2007 trailer brake wiring under hood question"

TIP: The red/black circuit 242 must be connected to Stud 1 (30 amp) of the UBEC. The wire is located between the left fender and the UBEC. Do not confuse this circuit with 742 (document 1706194) which is also red/black, and which is taped to the harness under the master cylinder. Circuit 742 is the 12 V supply to the 7 way trailer connector.

I just looked under the hood, and there plain as day was another wire coiled up under the master cylinder and taped to the outside of a wiring harness.  THANK YOU !

Perhaps my dealer should join the forum....they told me I'd have to leave the truck with them to fix, since it was "probably a defective wiring harness" that they'd need to replace.

[Trail Blazer]

I just double checked this in the shop manual, and you are absolutely correct.

I have often been confused on these fuses, so I made sure to look it up before I posted. Unfortunately, I didn't look in the shop manual, but instead read the tag on the Z82 trailer harness which just happened to be handy.

(Someone else posted it, I don't know who, I will just reference their picture)

Now I know where my confusion has come from.

This states to install the supplied 40 amp fuse in stud 1. Silly me assumed that it was for the trailer brakes.

The shop manual wiring diagrams clearly state that Stud 1 (40 amp) feeds the battery supply to the trailer plug on pin E, while Stud 2 (30 amp) feeds the trailer brakes.

So, why would the fuse for the trailer brakes always be installed, but the fuse that does not go with the brakes is not installed, but included with the brake harness and referenced in the brake wiring instructions? Seems like they are trying to confuse people.

I'm sorry if I led you astray in my previous post, I have updated it to prevent future confusion.

Thanks for straightening it out, Avid.

-- SS

[n24005]

Hi,

New to the group, but I've read this whole thread and searched the others...

Like someone a couple of years ago, my trailer RH blinker/brake light does not work.   I have tried 2 trailers.  I also removed the socket from the back of the plug and found that the pin does not have power.

I checked all of the fuses under the hood...   There did not seem to be a specific fuse for LH/RH trailer blinker/brake.   But I pulled and visually checked them all anyways.

The Av's RH blinker/brake light DOES work.

Any suggestions?  Any wiring diagrams around?

Thanks,
Jeff

[fmcdaniel]

Thanks to the information on the thread, I was able to figure out how to get power to the plug at the rear of my AV.   There is a lot of helpful information here.  
Thanks to all for the help.

[n24005]

So, I finally figured out what the problem was with my trailer light (one side worked, the other didn't).

I learned about the 2nd fuse panel behind the instrument panel!  The "IP Fuse Panel" is behind a trim piece on the left hand side of the instrument panel.   You need to open the driver door to get to it.   I had suspected that there was one, but they did such a good job of hiding it, I couldn't find it!

Even after learning about the panel, I don't think I found anything in the owners manual about it!   It was a wiring diagram that I got from a friend that finally clued me in!

Thanks,
Jeff

[Dudeman258]

Hey guys, first post here.

Well my dad just picked up a 2007 lz, with towing package.  I am trying to hook up the electric brake controller.  First off, I cannot get the under-hood fuse box apart and don't want to break anything while doing so, any help would be appreciated.  Second, I am also trying to figure out (Buy searching) how to connect the electronic brake controller under the dash.  I have read bits about there being open wires taped under the dash.  Yet I also see the open plug buy the brake pedal in that box.  It looks to be a 8 pin hole, yet everything I have read talks about a 7 pin.  I have looked and looked and cannot find any open wires taped up either.  My dad and I went to all kinda of stores looking for an adapter (Current brake controller harness has a 6pin plug).  We need to get this working buy Friday, so any help would be appreciated.  I am a car person myself, but I love this new truck.  Hoping someone can lend me a hand.  Sorry if this has already been covered, it is hard to understand allot of this as I am new to these trucks.  

Dudeman

[SilverGhost]

I found my 4 wires taped in with 6-8 others.  Look on the far left under the carpet.  Don't forget to hook up the power loop taped in another bundle between the engine fuse box and the driverside fender.  There is a stud (no nut supplied) at the front of the fuse box for the power to be picked up from.  If I can remember I will take a look at mine and try adding a picture. 

Good luck!

[AVid]

First... to the club!

The easiest thing for me to do is to point you to this Site. It has instructions and pictures.

[omlifecrew]

I just found the answer to my last post under another thread "2007 trailer brake wiring under hood question"

The red/black circuit 242 must be connected to Stud 1 (30 amp) of the UBEC. The wire is located between the left fender and the UBEC. Do not confuse this circuit with 742 (document 1706194) which is also red/black, and which is taped to the harness under the master cylinder. Circuit 742 is the 12 V supply to the 7 way trailer connector.

I am looking to just get 12V power to the 7 way trailer connector red/black wire on my 2007 Avalanche.  If I follow the steps and connect the wires under the hood to the studs at the fuse panel without installing a break controller, will this work?  Will there be a live wire then under the dash where trailer wires are blunt connected?

[BigRedAv]

There is another wire (i think its the one below the brake booster) connect to the stud and it  goes straight to the trailer connecor. Its constant 12v power

[omlifecrew]

Yup. That's it.  Got power and harnessed it to run my firestorm LED. Thanks for everyone's help.