voltage question

[rp53]

i think i know the answer just want to confirm. if the TT is hooked to the TV and the TV is not running will it continue to draw voltage from the TV or do the TT battery take over. if it is drawing voltage from the TT if you used your electric jack would it cause a voltage drop on start up

[5picker]

Depends. Some tow vehicles are set up with relays that prevent drawing current from their chassis battery unless running or the key is on. Other vehicles are not set up this way.

Posting the make, year and model of your tow vehicle will get you better answers.

[rp53]

sorry it is in my sig. it is a 2014 chevy 4 door Silverado Z71

[5picker]

No apologies necessary. Signatures don't show up in the mobile app posts.

Unless someone else chimes in, when I get a chance to get to a computer, I'll look for a GM schematic.

[rockfordroo]

Most likely it will stay on. Easy to check. Turn off the engine, use a voltmeter to check the pin at the 1 o'clock position looking into the truck's plug. (See attached).

On my 2009 Silverado 1500 it was always on. I added a relay with a switch on the dash so I could turn it off. I haven't bothered to check on my Silverado 2500.

But my guess is that GM hasn't changed their basic wiring in years.

[markb5900]

Originally Posted by rp53

i think i know the answer just want to confirm. if the TT is hooked to the TV and the TV is not running will it continue to draw voltage from the TV or do the TT battery take over. if it is drawing voltage from the TT if you used your electric jack would it cause a voltage drop on start up

My 2013 chevy does not draw from the truck battery unless the truck is running

[Flybob]

Check the owners manual for the fuse block info. On some models there is a relay and a fuse and on others there is only a fuse. If there is a relay, usually the power to the aux pin on the Bargman is disconnected when TV is off. It is possible that the above referenced items are not installed but rather in a bag in the glove box. On the 1500 the items are usually not installed on delivery.

[Mr. Dan]

Originally Posted by rp53

sorry it is in my sig. it is a 2014 chevy 4 door Silverado Z71

Your sig. says it's a 2015 and that might make a difference.

My 2014 GMC Sierra has an always-on/hot charging circuit regardless of key switch. I metered it once switch off, switch on/not running, switch on/running BUTTTTTTTTTTTTttttttt I can't find my post.


EDIT: OK, I found my post.
"REVERSAL / RETRACTION!!

One of the worst problems on public forums is the definitive statement of opinions as if they were facts. Secondly, we are often merely wrong when we post things as facts. I do that myself although I'd rather think I didn't. I did that very thing on this thread.

My son is certified as a World Class GM Master Technician. When I told him my opinion on this subject (meaning that the truck's charging circuit is dead when the key is OFF), he said, "I think that's wrong." He went home and researched the topic from a GM perspective - meaning he couldn't speak for the other two of the Big Three or the other entries in the RV towing business. Here's what he wrote me.
"Positive cable off battery powers the HOT AT ALL TIMES input to the under-hood fuse block. The input to the 30A fuse is tied to this buss bar inside the UBEC. The output from the fuse goes straight to the 7-wire plug at the bumper with no relays, modules, switches or any other means for it to be remotely or automatically disconnected from the battery."

When members ask questions on this forum regarding a TV's (in)ability to tow a particular trailer, someone or more people will recommend that the OP weigh his particular rig to get real measurements/real numbers. I decided that might work for my 2014 GMC (please note I am not projecting this information on another manufacturer's units nor on older or differently configured GM units). I have a gas engine and a single battery on the truck.

Here are the voltage readings I found this morning from my 7-wire electrical socket measuring from tab marked - to tab marked + :
12.46 – key off,
12.19 – key set to ACC mode,
12.14 – key on; NOT running,
14.81 – key on and running; T/H OFF.

With my key OFF, I have 12.46 volts ON at the trailer plug/socket.

Even after all this, my operating procedure will not change since I always have the trailer plugged into 110v AC when it's parked up by the garage before a trip. Therefore, I don't worry that the trailer cord is plugged into the truck because I ASSume the 110v - converter link will keep my trailer battery up so my truck battery couldn't be "drawn down" anyway. I doubt if I'll have any problems leaving the trailer connected to the truck for 90 minutes while I eat a steak while I'm out on the road.

Thanks to my son, I'm now more educated about how my own truck works. Your mileage may vary. The assumptions I gleaned from poorly conducted experiments and experiences were WRONG. I'm sorry. Consider metering your own voltage!"

[rp53]

thanks great post

[rp53]

mr Dan,
i had forgotten to unhook before i started to setup and i levelled the TT with the elc jack with the truck not running
long story short later i needed to start the trick and it started to throw all kinds of code i have been told that if the battery drops below 9 volts this can happen just curious if the elc jack could pull enough voltage to have caused that

[Herk7769]

Up till at least 2008, the trailer "hot" was sent to the dealer disconnected for that very reason (Hot all the time). You had to manually install it yourself or tell the dealer you wanted to tow with it for them to install it (Ordering the two package was not enough apparently.

Here is the install manual page and the note that it will be hot all the time.

[rockfordroo]

Originally Posted by Herk7769

Up till at least 2008, the trailer "hot" was sent to the dealer disconnected for that very reason (Hot all the time). You had to manually install it yourself or tell the dealer you wanted to tow with it for them to install it (Ordering the two package was not enough apparently.

Here is the install manual page and the note that it will be hot all the time.

I'd say at least 2009. I had to hook it up on my Silverado 1500.