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toastie 07-30-2011 08:27 AM

Having and electrical problem with TV maybe
Having and electrical problem with TV; maybe. Itís a 2008 Chevy Trailblazer with tow package, want the TV to keep the trailer battery charged when traveling. With TV hooked-up to trailer and running and grounded, not seeing any volts to 7-way black wire. Is it possible that the Trailblazer doesn't have that option for charging.


tschat 07-30-2011 09:19 AM

Since you have the tow package, I am assuming the fuse is blown. There is a separate fuse for that line in your engine compartment fuse panel (not the fuse panel under the rear seat). Check your owner's manual for which one.


garry 07-30-2011 11:08 AM

I think you will have to "add" the fuse directions should be in the manual or give Chevy dealer a call.

jdalrymple 07-30-2011 11:21 AM

The advise above is on the right track. The wiring is probably there, may just need the fuse replaced or plugged in.

Best of luck.

toastie 07-30-2011 12:06 PM

2 Attachment(s)

Originally Posted by garry (Post 1025731)
I think you will have to "add" the fuse directions should be in the manual or give Chevy dealer a call.

Found this on a Chevy Trailblazer forum Fuses for trailer lights? [Archive] - Chevy TrailBlazer, TrailBlazer SS and GMC Envoy Forum "The +12V constant feed is the one we've been talking about in this thread. Many trailers have batteries on-board that are recharged while driving by this wire. RVs have them for running lights, furnace, etc. Any trailer with electric brakes should have a small one with a breakaway switch to apply the trailer brakes in case it falls away from the tow vehicle. Not sure if your trailer has a battery or a breakaway switch for the electric brakes, but it really should if it's a heavy one. My 2500 pound Trailmanor popup has one.

Many folks hook up trailer brake controllers just fine, but get confused about this +12 constant feed. It's a ring lug under the cover of the front (under hood) fuse box, but it comes from the factory NOT connected to the threaded stud it needs to be. We've guessed this is because many folks don't need the feature, and never tow, and having a source of constant +12 on a 7-pin connector they never use could surprise them if they poke about and short it to ground.

You need to find and put the ring lug on the threaded stud, and then find a nut to fit. I would have guessed it's a metric one like almost everything else on the vehicle, but I don't know what I used for mine - I just dug in my junk bin until one worked, and I suppose my junk bin is about 20% metric.

I've seen many pictured of this posted before, but can I find one this morning? No. Sorry. I'll take a picture if it isn't clear when you lift the lid on the front fuse panel.

Once connected to the threaded stud, the circuit is fused by 30A fuse 32 under the hood, and goes straight back to the 7-pin Bargman connector under the bumper.

Just in case anybody's searching and finds this message later, here's some more data from another post of mine about the other circuits:

About the wiring bundle under the dashboard meant to hook up a brake controller:

The four wires are a fused +12 to run the controller (not coming from the red wire under the hood, but a separate 30 Amp fuse 19 under the hood), a brake switch line from the pedal, an output wire from your controller to the rear 7-pin trailer connector for trailer brakes, and a ground.

Just as a note for anybody finding this post in a later search, trailer lighting is separately fused from the vehicle lamps to make sure a short in the trailer harness can't take out a vehicle circuit. Backup lights are fused under the hood by 10 Amp fuse 4, left turn signal is 10 Amp fuse 51, and right turn signal is 10 Amp fuse 50. Park/running lights to the trailer are fused under the rear seat (!) by 10 Amp fuse 42"

Here is a picture of mine showing showing the red wire and the stud, and next to the stud is j-case fuse #32 TRLR 30 amp (pink fuse). I also have another 30A fuse insdie of trailer as shown in the picture.


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