Tow package: Accessory line

willieboy · March 15, 2005

I have the 7 pin tow wiring connector on the Burb. Today I was checking to make sure everything was wired correctly before hooking up the camper this weekend. Anyway, I noticed that even when the truck is off, the accessory 12 volt line is still supplying power. Now is it me, or is that just a dead battery waiting to happen. Why would Chevy do this? Why not relay isolate it?

So, does anyone no where the 12 volt accessory line for the tow hitch comes into the Under hood power center? Is the wire still red? I am for sure going to relay isolate that one. The last thing I need is for the fridge or the camper battery to run the Burb battery down while I am out in the middle of no where.

AG Bill 05 Z71 · March 15, 2005

Per the manual this red wire goes to a 40 Amp fuse in the underhood fuse block marked Stud 1. It is a red wire all the way, and is identified as Battery Positive Voltage.

builderpaul · March 15, 2005

I have the 7 pin tow wiring connector on the Burb. Today I was checking to make sure everything was wired correctly before hooking up the camper this weekend. Anyway, I noticed that even when the truck is off, the accessory 12 volt line is still supplying power. Now is it me, or is that just a dead battery waiting to happen. Why would Chevy do this? Why not relay isolate it?

So, does anyone no where the 12 volt accessory line for the tow hitch comes into the Under hood power center? Is the wire still red? I am for sure going to relay isolate that one. The last thing I need is for the fridge or the camper battery to run the Burb battery down while I am out in the middle of no where.

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It is like your power ports, they are hot all the time. Operator error is the only way to get a dead battery. Instead of adding a relay you could just unplug the trailer. The best system is the isolated battery option. You can use 12v, in the trailer, all you want and startup in the morning.

az'03Silverado · March 15, 2005

Don't these trucks have 'rundown protection' that cuts the power from the battery after 10-20 minutes if there's a draw? Try this as an experiment. Hook something up to the hitch accessory line and run it for about 20 minutes (trailer dome light or something) and see if the battery cuts out. It should.

willieboy · March 15, 2005

Don't these trucks have 'rundown protection' that cuts the power from the battery after 10-20 minutes if there's a draw? Try this as an experiment. Hook something up to the hitch accessory line and run it for about 20 minutes (trailer dome light or something) and see if the battery cuts out. It should.

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If so, that would explain the reason they did not relay isolate it. However, I know the power plug are not part of that system, cause I left my cell phone charging this morning, and it was still charging when I checked back an hour later. I do know the dome lights will shut of after about 20 minutes, but I am not sure about the rest. Maybe I will check it this weekend.

dewfpo · March 15, 2005

The battery protection does not cut off after a certain period of time. It cuts off off (isolates) the battery when a certain battery voltage is reached. So you should be able to plug in your cell phone and have it charge no problem since there isn't a big current draw on the battery.

DEWFPO

willieboy · March 15, 2005

Well that is too cool. Saves me some wiring for a relay, etc...

kdm101 · March 17, 2005

I don't know what it's like on the latest trucks, but my '99's "Stud 1" feeds directly from the main 12V stud on the electrical center that attaches to the battery cable. There's no relay or other type of electronic cut off device that I can see (I've had the electrical center half dismantled already). So, if there is a draw on that lead from the trailer, my guess is that it's going to kill the battery.

Lighting and accessories are all controlled through the body control module, so it's easy for it to determine that the load is still there and cut the accessory off.

marman · March 17, 2005

I don't know what it's like on the latest trucks, but my '99's "Stud 1" feeds directly from the main 12V stud on the electrical center that attaches to the battery cable. There's no relay or other type of electronic cut off device that I can see (I've had the electrical center half dismantled already). So, if there is a draw on that lead from the trailer, my guess is that it's going to kill the battery.

Lighting and accessories are all controlled through the body control module, so it's easy for it to determine that the load is still there and cut the accessory off.

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kdm101 is exactly correct. I installed a selonoid type isolater in the trailer power line and spliced into one of the circuits in the power center so it would only be on when the iginition switch is in the run position.

willieboy · March 17, 2005

kdm101 is exactly correct. I installed a selonoid type isolater in the trailer power line and spliced into one of the circuits in the power center so it would only be on when the iginition switch is in the run position.

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Did you use a circuit in the underhood power center, or in the cabin? Which circuit did you use? What I am thinking is I may use an ignition cycled circuit to power a switch that will open and close a solenoid/relay. That way, I can turn off that accessory line when I am backing a boat trailer in the water, but I can turn it on when pulling the camper.