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Chevy Silverado and GMC Sierra Trailer and Towing Questions



  • 77077707 Posts: 4
    Do you need a trailer controller installed under the dash in order to power the 7 way trailer plug at the rear.Or,does the 40 amp red wire #1 stud send power to the plug if,thats all thats hooked up.I just want 12 volts back there that I can access.Tnx.
  • catamcatam Posts: 331
    Yes you need a trailer controller if you are using elctric brakes on your trailer.
  • 77077707 Posts: 4
    Not pulling a trailer. Have left turn right turn at plug.But no power on the positive blade/pin.Put in the fuse ,have power on both posts on fuse box under hood.I just want to get power to the positive blade in the plug.Is the only way to do it thru a brake controller.I dont plan on pulling anything. i jast want to be able to run my cooler in the bed of my p/u without having to run a power extension in thru the back door.Tnx
  • No brake controller needed to power the 12v Constant. Remember, the center pin is the backup lights, not the constant. The brake controller is only needed if you're using the brake output to control electric brakes. There is probably another issue somewhere between the fuse box and your trailer connector if you're not getting any juice. On my truck, 2000 Silverado 1500, there is a fuze about 2" behind the 7 pin connector that is connected to the 12v supply, so you might check that as well. I use mine to power an inverter that powers my RIGID cordless tool chargers so I can charge between jobs. Works great! But remember, depending on your power draw, you might do better to run a new cable under the chassis. Even though the fuse is rated to do everything I need to do, my inverter cannot pull enough juice down that 14awg wire to do anything but charge batteries. However, if I connected with a shorter wire, or a 1O wire, it will run at it's full 1000watt capacity. Just something to keep in mind if your cooler doesn't perform like you think it should. Good luck!
  • 77077707 Posts: 4
    edited February 2010
    Thx for all the advice on the constant power. It turned out it wasnt me being brain dead after all. The guy before me either rewired or removed the constant red lead. I took it into a dealer ,and at first they said ,you have power back here.To which I replied,yep,but not on the red.To that they agreed,and ended up rewiring it thru the red/black brake controller wire.I think they tapped into it.But you know them,trade secret.i will investigate exactly what they did later today. The 30 dollar fix won't kill me.After all,it took them over an hour to diagnois and repair. I went under the hood and the truck too many times to count.Tnx again.
  • califjimcalifjim Posts: 2
    :confuse: I installed the 7 pin trailer plug in my (2009 GMC Sierra 2500) truck bed today, and apparently need to connect the 12v power wire and trailer brake harness wire. I found the two wires under the hood, 1 taped to a wiring harness underneath the master cylinder (not marked) and the other between the master fuse box and fender wall (marked aftermarket trailer power wire).
    This is where I need some input. I am thinking the Stud 1 and Stud 2 that was referred to in an earlier post referred to the driver side battery posts. Am I right? If so, maybe I don't understand the hookup, but why would the wire marked trailer power wire be connected to the negative terminal of the battery? I looked at the end connectors and they could go on either stud, however the wire lengths tell you which wire to has to be connected to each stud.
    Thanks for input.
  • dostie1dostie1 Posts: 1
    I recently installed a tailgate light bar on my 09 gmc sierra. 7 pin. It has brake/reverese/running lights white and red leds. The bar came with a 4 pin and a separate wire for reverse lights(white leds). The directions say to put the ground(white) to ground (white). running to running, and then brake, brake are the last two wires. NOW it is installed as this on the truck. White to white for the ground, and the running wire is wired to the parking lts and the other two brake to brakes I wired to the left blinker/brk and the other to the right blinker/brk. the running lights and reverse lights work, but when the brake is pressed, the leds don't brighten up. now if i hook both the brake/brake wires from the light bar to the left blinker wire only it lights up when the brake is pressed BUT if i put the blinker on to the left, the blinker on the truck and the light bar blinks with it. Nothing happens if i wire it to the right blinker which is very odd. Are there fuses separate to the wiring harness? i have no idea. any input would be appreciated. Thanks!
  • tymyerstymyers Posts: 7
    Hey bud,
    There are different fuses for each of the 6 functions of the wiring harness. They are located under the hood in the engine compartment and are labeled accordingly. Check those and let us know what happens. Does sound like the issue is in your fuses. Sometimes they will blow even if the harness is never used if it gets wet.
  • usmc23usmc23 Posts: 1
    i have a 01 silverado and when i hook up the trailer lights i get parking lights, when i use the left turn signal both rear lights flash. when i use the right turn signal i get just the parking lights and when using the brake i get nothing everything shuts off. i used a hopkins wiring kit and installed to their instructions. what could this be???
  • The stud 1 & stud 2 you ask about are on the front side of the big fuse block under the hood. Those wires do not go to the "battery" terminals. The trailer "hot" wire should go to the stud closest to the fender.
  • jgc61jgc61 Posts: 1
    I have a 2003 Silverado 1500 4X4.

    6 of the pins work as required.
    Running Lamps
    Left Stop/Tail
    Electric Brakes
    Right Stop/Tail
    Back Up Lights

    The pin marked + has no power.
    I believe this should have power at all times
    I need power at this pin to activate the deck lights on my Imperial car trailer
    Thanks for your help
  • gewccwgewccw Posts: 1
    I have a 1999 Sierra and just installed a 7 pin trailer plug, replacing the 4 wire plug that was there. All the pins are working except the Aux power one because I could not figure out which wire to hook it to. I installed a 40amp fuse in Stud 1 and I have 2 batteries, but the connection point does not have power going to it when the car is on or off. I also looked under the master cylinder and there are no wires taped there.
    SO, can you tell me which wire is the aux power (switched 12v) wire so that I can hook it to the 7 pin receptacle?
  • ajhamelajhamel Posts: 1
    I have a seven pin connector on the truck but the brake light wire is not hooked to it, thus I have no break light on my trailer. Will a tail light converter fix this problem? I tried to splice the brake light wire to the left/right turn signal, but when I have the break pressed in the blinkers will not work.
  • saintsxlivsaintsxliv Posts: 1
    I have a problem with the harness on my Chevy. The only power I have at the harness is the park lights ( no turn or brake lights) all fuses check good.
    Any help is appreciated!!
  • middy1middy1 Posts: 1
    I have a 2002 Silverado. Factory wiring without a brake controller inline. For some reason I have power out of the + trailer brake position on the 7 pin on the truck. Can't figure it out. Only about 2.5 V. Seems to be enought to supply the magnet on the trailer brakes. Seems like the magnet engages enough to drag and push the front brake shoe causing it to drag. I have installed a Brake controller. Also have safety brakeaway switch. With that said, the problem exists with or without the controller. I sure hope there's someone with experience in this department. Any help or suggestions would be awesome at this point......

  • jsealyjsealy Posts: 1
    Have a new Silverado 1500, 4,8L V8, 4sp auto, trailering package (trans cooler, limited slip diff, transmission trailering switch for trans, hitch and wiring) and brake controller. Chevy rates this truck with its 3.23 rear for 4700 lbs towing. I purchased the truck to trailer a 3000 lb piece of equipment, but the trailer I want to purchase weighs 2100 lbs. So I will be 400 lbs over.

    I plan to add a transmission temp guage. I would appreciate any comments.

  • covemancoveman Posts: 5
    Just purchased a 2010 Sierra 1500 Z71 and was advised that it could tow up to 9700 pounds. First trip out, I discovered the truck is unable to handle my trailer that has a dry weight of 7500 pounds and do not exceed 8500 pounds gross. Unable to exceed 50 miles an hour due to excessive swaying and has been advised by the RV dealer to park the trailer due to a safety hazzard. The RV dealer has checked out the trailer, hitch and all attachments with no issues. The GMC dealer checked out the suspension and found no problems either and then suggested a tire upgrade, done that with 10 plys but did not help. Now they are suggesting air bags??? To be installed tomorrow. They also advised me that I was the first case reported but now learning it may be a common problem with the new models. Older models with the same specs as mine, tow the trailer fine. Wondering how common is this problem and looking for suggestions on how to rectify my problem.
  • grizzly4grizzly4 Posts: 12
    Do you have an equalizer hitch? What's the tongue weight on the trailer and max allowable tongue weight for the truck?
  • covemancoveman Posts: 5
    The hitch is a Reese with 1200 pound bars and I'm using the dual cam sway control. The tongue weight of the trailer (Jasper Trail 29RKS) is 748 pounds empty. The tongue weight for the truck with weight distribution is 1100.
  • gmcustsvcgmcustsvc Posts: 4,251
    Hello Coveman,
    I apologize that you are experiencing a problem with your vehicle. Can you please keep me informed on the fixes go. Can you please email me your VIN so I can look to see exactly what your vehicle should tow for you? You can get my email by clicking on my name. Thank you,
    Mariah GM Customer Service
  • grizzly4grizzly4 Posts: 12
    Are the truck and trailer level when the equalizer hitch is connected? Can't thank of any other reason for it to have such a large sway problem. 750 pounds is a lot of tongue weight. Good luck
  • covemancoveman Posts: 5
    Even though the trailer is within GM's posted weights of 9600 pounds for trailer capacity (7538), and 1100 tongue weight ( 748) it has been concluded by some GM staff, the RV dealership and other professionals the truck is unable to safely tow my trailer. At this point, my only option now is to downsize the trailer...has not been a great week. Vehicle was purchased based on online searches, GM specifications, discussions with persons who own vehicles 2007 and older and four different GM salesmen at different dealerships. All advised the truck could tow the trailer. Great truck for a car, but I wanted a truck...strange two older models with lower posted towing capacities than mine could tow the trailer without a problem, the 2009's and 10's not a chance. I have exhauted all avenues with the GM dealership and I am stuck with a truck that I wish otherwise. Fortunately for me, the RV dealer came through and gave me a full refund and offered a new downsized trailer whick I have accepted. I am hearing horror stories oll over the province similiar to mine. From suggestions from various GM staff I ungraded tires, installed air bags, and done everthig possible with leveling and several other changes for the past three weeks...all at my expense with one execption, the dealer installed the air bags I purchased. Anybody out there having the same delemma?
  • grizzly4grizzly4 Posts: 12
    Sorry to hear that Coveman. I upgraded my trailer and truck last year. I used to have a 2003 Chevy 1/2 ton ext cab. Now we have a 2009 Ford F150. It pulls our NRG Toy Hauler all over and up and down the biggest mountains with ease. I live in Montana and we have big hills. I installed air bags. Sure wish GM would get with the program. I loved my Chevy truck. BTW, I wanted to buy a new Chevy but couldn't get a 1/2 ton that would pull the trailer.
  • covemancoveman Posts: 5
    edited June 2010
    I hear you, if I did not need the truck for heavy duty towing, I would love my Sierra too. I sure wish GM produced a 1500 model that retained the older models towing capabilities. Ironically, one of the older trucks I used to sucessfully tow the trailer was a 2003 chevy, great truck. As soon as I can, I plan to unload the GM and possibly get a Ford as well. Hear they are getting great mileage and have great towing abilities, they appear to have come a long way over the past couple years.
  • covemancoveman Posts: 5
    Today my dealer installed new rear leaf springs (under warranty) which made a remarkable positive change to the overall performance to the truck. Apparently the truck was rust proofed and the dealer is suspecting this to be the cause of rubber/bushing failure in the springs.....similiar local experiences are being acknowledged with other GM' trucks as well as trucks from other dealers. Interesting. Not sure if this will address my towing issues until I give it a go in a few weeks but right now it sure is looking good. Will advise.
  • big_al2big_al2 Posts: 1
    hello folks, i have a 2004 silverado LS no towing package, no transmission cooler. What can i do to pull a 5000 lbs. trailer? :surprise:
  • obyoneobyone Posts: 8,054
    airbags and an aftermarket trans cooler
  • Hey obyone -
    my gmc sierra doesn't have a towing package either. I've installed a hitch but haven't been able to find the factory plug for the wiring harness. Where have I missed it?


    :( :confuse:
  • Hey, I have a 2007 Silverado 1500 with tow package. I am getting no power to the center pin (reverse) on my 7 pin plug. I am getting power to every other pin and have checked and replaced all fuses. Any one else have this issue?
  • Hi, I am trying to buy a travel trailer, but don't know what weight I can tow... my husband (out to sea) said don't get anything over 21'... but I can't figure out the whole weight thing; ie tongue, dry, wet, etc!!!
    I have a 2003 Silverado 1500 extended cab with a 6 cyl 4300 and has towing gears on the transmission ???
    The book says it has" tow-haul mode on automatic transmission
    max trailer weight "4700 or 5200lbs"
    I'm looking at a terry resort trailer 24'.
    does anyone know where i can find the info on how much the trailer weighs or would it be printed somewhere on the chassis or interior?
    Thanks for the help!
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