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2007 chevy trailblazer_lt
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Discussion Starter · #1 ·
I was cleaning the engine compartment today and I came across this red wire with a wire connector at the end not connected.

Can anyone please tell me what this goes to? (pics attached)

(this is the wire looking when you are standing on the drivers side of the truck)


(this is looking from the passenger side of the truck)


(this is looking from the front of the truck)


I have no idea what this wire goes to, so if anyone has any idea or knows what it goes to please let me know.

Thanks a lot!

Steve A.
VA Beach, VA
 

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2003 gmc envoy_slt
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That is the wire for a 12v power source at the trailer light hook-up. If you need a power source for a fridge or ? in your trailer. It connects in the fuse box.
 

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Discussion Starter · #4 ·
See there you have it! Thanks a million guys! I appreciate it. Its a good thing that I didnt need to power the trailer this past weekend when I went camping.

Again, thanks for your help and I am sure that I will be asking more questions as I come across something on the truck.

Steve
 

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I have the same red wire not connected, just hanging loose like Steve A. I don't forsee needing it for anything, now that I also know what it is for. Why would Chevy. leave a loose wire and not go ahead and connect it? Should I leave it loose or connect it even though I don't think I'll be using it. Thanks for the great information.
 

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2005 gmc envoy_sle_xl
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That is the wire for a 12v power source at the trailer light hook-up. If you need a power source for a fridge or ? in your trailer. It connects in the fuse box.
I have the same red wire not connected, just hanging loose like Steve A. I don't forsee needing it for anything, now that I also know what it is for. Why would Chevy. leave a loose wire and not go ahead and connect it? Should I leave it loose or connect it even though I don't think I'll be using it. Thanks for the great information.
thanks for asking this question. i always wondered what that was. I always forgot to ask though. so thanks!
only need to connect it if your going to be using it to supply 12v to your trailer, like WOOLUF said in post 3 its for recharging a trailer battery or supply for a 12v "option" in your trailer :thx
 

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Why would Chevy. leave a loose wire and not go ahead and connect it?
Because there's a tiny risk that somebody will poke a screwdriver in the trailer connector and short it out and get injured by a spark and sue GM?

Seriously, I think it's because the RIGHT way to hook it up is through a solenoid that only closes while the tow vehicle's engine is running. That way when you park for the night at a motel while towing the trailer on a multi-day trip, and leave the 10 Amp fridge running in the trailer, it won't drain the tow vehicle battery as well. Or you put in a high tech battery isolator on the circuit. GM didn't want to burden all the vehicles with something only of use to a tiny minority of owners. So they left the ring lug off the stud, but nearby. They also saved the cost of a 6mm nut/wingnut as well.
 

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Seriously, I think it's because the RIGHT way to hook it up is through a solenoid that only closes while the tow vehicle's engine is running. That way when you park for the night at a motel while towing the trailer on a multi-day trip, and leave the 10 Amp fridge running in the trailer, it won't drain the tow vehicle battery as well. Or you put in a high tech battery isolator on the circuit. GM didn't want to burden all the vehicles with something only of use to a tiny minority of owners. So they left the ring lug off the stud, but nearby.
Thanks Roadie, I suspect your above idea is dead (battery) on. I can hear all of the complaints from owners that ran their vehicle's battery down overnight because they didn't know to or forgot to disconnect the trailer connection if they didn't have a battery isolator.
 

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This seems related to the original topic...

Can someone explain to me how the charging system works on a trailer?
Let me explain: I recently purchased a used pop up camper. It has lights, AC, heat, fridge, etc. It also has a battery box on the tongue, I just need to add a battery. I know that I can use the battery at campsites without hookups, and I know I can use the battery to power the 3 way fridge while driving.
But how does the battery get charged?

The trailer wiring to the truck it only 4 wires, however, there is a 6 pin connecter on the trailer frame and the wire harness coming from it goes to a 4 wire plug that connects to the truck. (confusing I know)

So question 1: How does the charging work?

Question 2: Is there something that needs changed on my trailer wiring harness?
 

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So question 1: How does the charging work?

Question 2: Is there something that needs changed on my trailer wiring harness?
Charging the battery is normally done by a small charger built into the fuse/circuit breaker box of the popup, when its AC cord is plugged into 115VAC at home or at a electrical hookup campsite. If it's an old one, it might have a common design flaw of being a battery OVER-charger that will boil the water off if left hooked up for more than a few days. If you can get the model number and a picture of it, I know a little bit about these units and can advise.

Charging the battery from the tow vehicle while driving is the purpose of the ring lug this thread is discussing, but then you need a different wiring cable from the 7-pin "Bargman" standard connector on the trailvoy to your 6-pin connector on the popup.

Does it look like this:
or


Probably nothing needs to change on the popup side. Do you have a meter in case I recommend a few things you should check?

Does the popup have electric brakes, or is it old/light enough to not have them?
 

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I will have to get some of those details at home over the weekend, but I do know these things.

It is a 98 Jayco. Owners manual is VERY vague in this area. It just says that it will charge, but never says from where.

The previous owner said he replaced the pop up electric converter last year. I will search for a model or brand on it over the weekend.

I do need to hook up the wire as mentioned in the OP. The frame of the trailer has a female version of the connector that you show on the left, and from it is a mess of wires that looks like it ties into the battery box and then goes to a 4 pin connecter. I used the four pin with an adapter and all of the running lights, brake lights, and turn signals work fine.

Popup is about 2100 lbs, so no brakes, and I have access to a meter.

Are we on the right track so far?

Thanks Roadie!
Bill
 

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What you'll need from the local parts store is a 7-pin wiring harness (connector and cable) that will replace the 4-pin kludge.



Depending on your enthusiasm for a robust connection you won't have to ever troubleshoot again, you would cut off the 6-pin connector on the trailer, or buy a mating one at the parts store. Then trace the wiring from the 7-pin vehicle end to the 6-pin trailer end and splice or solder it together. Make a wiring chart as you go along. Here is the wiring definition at the 7-pin end:

 

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OK, cool. We are getting there.
So, On the 7 pin wiring harness that you show, I will use everything but blue because I don't have brakes.

Then, once I have done that, connected the wire under the TB hood, and added a battery to the pop up, do I have the following correct?

I could power the fridge on the road from battery, AND the RV battery would be charging. (OR I could use propane for the fridge on the road, but I'm not a big fan of that idea.)

At camp, if I used electric hookups, lights and fridge would be powered from that, AND the RV battery would be charging.

If I DID NOT camp with hookups, then the RV battery would power lights and the fridge. It would then be charged by the TB on the return trip.

Is all of the above correct?

Assuming it is correct, could I expect 2-3 days of RV battery use with the fridge and moderate interior light use without completely draining the RV battery?

I appreciate all of the advise.
Bill
 

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You got it. The fridge will draw a lot of power though and probably won't even last the night on 12V. Best to run it on propane when not travelling or hooked up to shore power.

I think the pin labelled Auxiliary on Roadie's diagram is really the reverse lights. You proably won't have them on your trailer either.
 
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