Chevy Silverado and GMC Sierra Trailer and Towing Questions

swift1069swift1069 Member Posts: 5
I have a 2004 chevy silverado and I'm having trouble with the wiring for my tow package. When I turn off my truck I am still getting power running to my park lights on the left side of the trailer, but not all the lights on the left light up just 3 on the left brake and two on the top brake light on the back of the trailer. Also I am having problems with the left blinker not working on the trailer off and on... I've replaced all the fuse under the hood and in the dash for the trailer and even for the truck.. I've replace the ground wire to the trailer and cleaned the ball to insure a good ground and nothing has worked.if anyone could help I would sure apprreciate it...


  • gmctruckgmctruck Member Posts: 186
    You should recheck all of your wiring connections. Use a 12v test light to check the wiring at the electrical connector without the trailer wiring connected. This will also help you verify which wires are for brake lights, turn signals, park lights, ect.

    This test should tell you if the problem is in the truck wiring or the trailer wiring. The ground goes through the electrical connector and not the trailer ball. Some trailer wiring packages have a 12V supply wire that is hot all the time and is not tied to the ignition switch. Make sure you didn't hook the lighting into that supply wire by mistake. Sounds to me like you either have a bad connection or the wiring is incorrect.
  • swift1069swift1069 Member Posts: 5
    The wiring in the truck came from factory and was working perfect up to a month ago... I've hooked the trailer up the my other truck and it works perfect no problems and I've tested the plug on the 04 with the problems and the running light wire has a constant power to it with everything off in the truck.. I pulled the fuse for the wire and the power is gone. I replaced the fuse and still have the same problem...
  • gmctruckgmctruck Member Posts: 186
    The fuse only protects the circuit from excess current flowing through the wire and will open if the specified current rating limit is exceeded. You could still have a bad connection in the factory wiring or the wiring harness could have been pinched or damaged. Double check the ground wire connections to the chassis for loose connections or corrosion. Which fuse are you pulling that kills power to the wire? What other things does that fuse or circuit feed?
  • swift1069swift1069 Member Posts: 5
    I am pulling the fuse for the running lights to the tow package wire. From what the book says it controls the left blinker on the truck too. But I am not having any lights on the truck staying on or even any problems with the lights on the truck.. I am sure it's something to do with the running lights wire on the tow package harness. Today I am the left brake light stopped working on the trailer too, and the other problem is still continueing. So I connect my second truck to the trailer today and everything is still working perfect on that truck. So I'm thinking the only thing I can do is to take it to a shop and have the wiring tested and maybe replaced..
  • 04cad04cad Member Posts: 131
    Hi, I have a 2006 Silverado and have just installed the trailer brake wiring harness and my electric brake controller. My question is: when is it necessary to install the included fuse? I had been told on earlier Silverados that the fuse did not need to be installed. The tag on the pigtail makes it as clear as mud. I don't presently have an auxiliary battery, but what if I add one such as on a battery mounted on a trailer for a winch? Thanks
  • gbrewergbrewer Member Posts: 7
    I have a 03 2500HD to tow my 5th wheel. When I installed the break controler, I did not instal a fuse. Been towing for almost 3 years without any problems.
  • ahoronahoron Member Posts: 30
    I have a 2002 no fuse no problem.
  • rswordenrsworden Member Posts: 4
    2004 Silverado with factory tow package, 7-pin connector. The 12v pin is not supplying any power. I'm pretty sure it worked before, charging up my trailer battery. All other pins work fine. I imagine it's protected by a fuse, so that's what I'd check first. But none of the fuse descriptions in the manual or in the fuse boxes seem to apply. I've pulled all the high-amp fuses and all look good. Is there such a fuse?

    If not, what else should I check? The connector into the "fuse box" (really a connector box) under the steering column seems tight. If I knew which lead should be hot, I could check for 12v there.

    Any other connectors along the route to the bumper that I should check?

  • rswordenrsworden Member Posts: 4
    I solved the problem - posting it here in case it can help someone else. A friend of mine was pretty sure there was a 40-amp fuse, because he installed it with the tow package on his 2002. Another online forum mentioned a fuse in the location Stud 1. In my case, there was a plastic filler plug in Stud 1, not a fuse. Plugged in a 40-amp fuse, and now I have 12v on the correct pin.

    So it had never worked before - we have always charged the trailer batteries from house power before our weekend trips, and on longer trips we have had 120v in the campgrounds, so we never noticed that it was not charging up while driving.
  • geo9geo9 Member Posts: 735
    Before you start going crazy.............

    To power up the pin in the trailer connector
    (for trailer battery charging) you MUST intall
    a maxifuse in Stud #1 slot in the underhood fuse
    center. There should be a plastic plug already
    in place which you will have to remove and insert
    a maxifuse....................
  • nibby50nibby50 Member Posts: 4
    We have a 2000 Chevy Silverado 1500 extended cab. We are planning to pull a travel trailer and are trying to figure out how much weight we can safely pull. I think it is rated for around 7000 lbs but how much can it really pull without doing harm to the truck?
  • obyoneobyone Member Posts: 7,841
    To supply that info additional information is needed. Like what size motor? gear ratio? 2 or 4wd?
  • jreaganjreagan Member Posts: 285

    I currently own (for a couple more weeks anyway, til my new one comes in) a 2000 GMC Sierra Ext cab Z71 4x4 with the 5.3 liter engine and 3.73 rear end. It is rated at 8500 lbs towing, however, I do beleive that these so-called max tow ratings are greatly inflated beyond what is reasonable for a 1/2 ton chassis if you want them to last.

    I tow a boat that weighs around 3500 lbs with gear, gas, etc. The truck pulls it fine, but it is working. Personally, I would not recommend towing much more than 5000 lbs, assuming you have the 5.3 with the 3.73 gears.
    How much does your trailer weigh? If it is more than 5000 lbs, I would consider getting a 3/4 ton.

    Also, take care of that tranny, do a complete flush and filter change if it hasn't been done yet. Regardless of that BS 100,000 mile tranny fluid life they claim. These trannys are not the best for towing alot of weight, so meticulous maintenance is required if you want them to last.
  • nibby50nibby50 Member Posts: 4
    My husband probably knows more than I do (!) but I do know it is 4.8 and not 5.3. It is a 4 wheel drive. Does that help?
  • nibby50nibby50 Member Posts: 4
    Thanks for the information. The trailer we are looking at towing weighs 2800 lbs. I think that is called its dry weight so it would weigh more than that when loaded.
  • hbilowhbilow Member Posts: 2
    I have a 2005 2500HD with the Duramax, with the same problem of no aux power in the trailer connector. I checked in the manual and it says DO NOT install a fuse in the STUD 1 location on vehicles equipped with the diesel or 2 batteries..... I have both. Any ideas?
  • rswordenrsworden Member Posts: 4
    Check out this official GM "Upfitter" document:

    I wish I'd found this earlier! Complete electrical diagrams and explanations. Page A-22 says you must install the fuse to activate the battery feed to the trailer connector.
  • hbilowhbilow Member Posts: 2
    Ok I tried that and it worked. That publication is awesome!
    Thanks a lot, I owe you a cold one!
  • rheckrheck Member Posts: 5
    Can anyone tell me where to plug in my electric brake control on my 2007 silverado "new body style" truck?
    Seems like the trailer dealer and my truck dealer can't seem to figure it out.
    It was no problem with my 2005 silverado, now all of a suddden no one can figure it out.
    Any help would be appreciated.
    Please e-mail me at: [email protected]

    thank you.
  • chrmdomechrmdome Member Posts: 107

    This took me a little research to get right and even the dealer who sold me the truck didn't know.. so here is the scoop! There is no pigtail wire set for the 2007 silverado ( new body style ) and even if you got the max trailering package the dwebs at chevy didn't wire the trailering electrical or the brake control wiring for you! What were they thinking....well they are offering an in dash brake controller in thier following series and they prewired it for that option.
    1) There is a bundle of blunt cut wires below the dash to the left of the steering column above the fuse box that is labeled and tucked around some other wires. Pull the blundle down. There will be 5 wires, with black electrical tape on the ends. Red and Black is the hot , positive battery wire, white is ground, negative. Blue and white is the input tail-brake light wire and the all dark blue wire is the trailer output brake voltage. The last wire, I believe , is for the brake controller light, but I am not certain. I did not use that wire. Consult your instructions . The next step is to open the hood, take off the top on the fuse box and locate space 65 and 70. Get a 40 amp fuse and put it into space that is labeled 65, this is the brake output voltage fuse, the voltage to your brake controller, post 65. the 70 space has a 30 amp fuse in it. Now go between the left fender and the fuse box and locate the red/black wire. This is attached to the post that is larger and silver on the front of the fuse box. Nuts not included. They are metric 10-1.5 course. the other black post is 8mm. Get the red black wire wrapped below the master cyclinder and attach it to the black post ( smaller ). You can't make a mistake with the wires because they can't be attached to the incorrect post, one is smaller than the other ( the opening ) The jist is that you need 2 nuts and a 40 amp fuse. Not supplied with the truck... now.. You are set. The reason for wiring the brake controller to the post is for 12 volt use from the main batter. If you use a secondary auxillary battery the wiring will be different . Good luck and thank chevy for making this a mystery or misery as the case may be. Read your manual under brake controller and it seems a little more clear, but just a little. I read it over about 3 times before I understood what they were getting at. Boy how could they not wire the trailering wiring.? Duh!.

  • bowtieladbowtielad Member Posts: 8
    I too have a "new body style" silverado. I need to hook up an electric brake also. My buddy at my dealership (he's the shop foreman) says there is a "pigtail" tucked up under the dash that is color coded for electric brakes. I haven't looked for mine yet, but that's where he says it is.
    It stinks that they didn't make it as easy in the past...but other than that...this truck is awesome.
  • rheckrheck Member Posts: 5
    Read the post after yours, (from bowtielad) he states there is a pig tail under the dash for the electric brake.
    But I tend to believe you, Chevy is looking to cut corners any way they can by giving us heartaches.
    Thanks for your response.
  • rheckrheck Member Posts: 5
    It may be awesome for some, but for me it's a dissapointment.
    I had XM radio installed, now I have an ugly wire haning from the dash to the radio, according to the installer, thats the only way to do it.
    The Wipers suck, wait until you have to buy blades, for now the only replacement blades are only available from the dealer ($30.00) until ANCO or TRICO invent an after market replacement blade.
    Good luck and thanks for your input about the brake, I looked, the dealer looked and the trailer dealer looked, there is no pigtail, it has to be hard wired, (see previous post) from another person who answered my post.

  • bdrainybdrainy Member Posts: 3
    Hi all. I am new the truck world and had a question about my new truck. I just purchased a 2007 Silverado 1500 Crew Cab 2WD with the 4.8L. My question is how much can I tow? I have checked the Chevy website and it indicates it is 4600lbs which seemed kind of low to me. The V6 extended cab can do 4400lbs. Why is there so little a difference between the V6 and the 4.8L towing capabilities?

    I am just missing something?
  • bowtieladbowtielad Member Posts: 8
    Sorry...I used "pigtail" out of context. There are some wires by the column for the hardwire. This is a disappointment. Chevy went this route because some aftermarket installers were getting some wires crossed and locking up the trailer brakes when the auto headlights came on. As far as your XM...I have Sirius and use the FM feature on it (no hanging wire). I mounted my receiver on left side of dash and ran antenna wire up under support beam trim and tucked my antenna wire into my headliner and hid it. My wipers are fine but I only have 3000 miles on my truck. Too bad these small things disappoint you about the truck. The performance and amenities in my Vortec Max Crew Cab 4x4 have not left me disappointed. The gas mileage is decent (~15 mpg) and the power is great. I pull a 33 ft camper with this truck in the West Virginia Mts. and I'm not at all disappointed.

  • geo9geo9 Member Posts: 735
    I have a GM tow guide handy but need to know......
    Do you have a GMT 800 or 900 truck(the newest body style)
    What is your axle ratio? Note: Look for code off RPO sticker located in glove box. Look for these codes:
    gu-6 3:42, gt-4 3:73, gt-5 4:10
    Automatic or stick trans.????

    Post them and can tell ya !
  • bdrainybdrainy Member Posts: 3
    Hi. it is the GMT 800 and it is a automatic. The only G code on the glove box sticker is GU-5. So I am assuming it has a 3.23 ratio. Thanks for you help!
  • geo9geo9 Member Posts: 735
    wELL according to my guide its gotta be a 3:42 rear so...
    It calls for 6800 lbs ball hitch towing
    6800 lbs. 5th wheel towing
  • bdrainybdrainy Member Posts: 3
  • leonchinleonchin Member Posts: 10
    i want to know whom of you are dealers of vehicle parts. who sell parts in market?
    who need filters? i have huge amount of it.
    do you know some more about the filters in vehicle?
  • columbiachuckcolumbiachuck Member Posts: 1
    Did you ever find out why the owner's manual says to not install a fuse in Stud #1? I got one of the 40 amp fuses but I am a little concerned about using after reading the message in the owner's manual saying not to use it.
  • rswordenrsworden Member Posts: 4
  • russo2russo2 Member Posts: 1
    Thanks allot for the information you posted, got me right to the wires I needed. Just curious as to where you found a good place to mount your brake controller (maybe a photo?).
    I'm installing the Hidden Hitch Pilot but don't see a really good place to drill 3 screws in a round mount into. The knee bolster is an option but I think that would look dang ugly in a brand new truck. Hope you ad an idea I haven't imagined? Thanks in advance.

  • chrmdomechrmdome Member Posts: 107

    Yes, I have a Prodigy. My choice of location was just above the emergency brake pedal, under the dash. It's actually out of the way there !There is one screw alerady in the under dash panel, I used it I drilled another small hole and only needed 2 screws to hold the bracket on. The unit does block the pedal somewhat but not enough to justify mounting the unit elsewhere. I've found no other place under the dash where I could mount the unit level and not bump my knee on it. All other
    places are ugly.

    Good Luck!!

  • paisanpaisan Member Posts: 21,181
    How do you hit the emergency engagement of the controller if it's down low?

  • davethecarnutdavethecarnut Member Posts: 248
    You should be fine. Just remember, if your going to camp spots with full hookups, make sure ALL your holding tanks are empty. No need to tow dead weight ;)
  • fishstewfishstew Member Posts: 2
    Recently got an 07 (really an 06?) Silverado Classic worktruck, 4.8 engine and a 3.42 rear with the "Smooth Ride" suspension. It wasn't set up for towing but the dealer agreed to throw in a tow package. That's the term. Now what does that mean? I was told the truck would be able to handle safely it's rated load which seems to be 6700 pounds. But they are talking about just putting in a harness and hitch. Is that all.
  • fishstewfishstew Member Posts: 2
    Recently got an 07 Silverado Classic 4X4 extcab worktruck, 4.8 engine and a 3.42 rear with the "Smooth Ride" suspension. It wasn't set up for towing but the dealer agreed to throw in a tow package. That's the term. Now what does that mean? I was told the truck would be able to handle safely it's rated load which seems to be 6700 pounds. But they are talking about just putting in a harness and hitch. Is that all?
  • paisanpaisan Member Posts: 21,181
    Dealer scammed you I think. A towing package is more than just a hitch I would think. But one of the GM folks on here will have to jump in to give some more ideas.

    On my Armada the towing package included:
    Power Steering Cooler
    HD ATF Cooler
    HD Radiator
    Tranny Temp Gauge
    Hitch w/Wiring Harness
    Air Leveling rear suspension
    and I believe a different axle ratio

  • cptchetcocptchetco Member Posts: 32
    Make sure your hitch set-up is correct for your truck. I regularly tow an 8,000+ boat and contents behind my 2005 Ford F-150 with no problems. It has a class 4 hitch, and the towing package, which as noted definitely includes more than just the plug in. Mine has different radiator and springs for sure. Its a 5 speed, 4WD. On freeways and long drives, its easy to forget your towing, its so effortless. Fuel mileage drops from 21 empty to 12-13 with the boat.
  • chrmdomechrmdome Member Posts: 107

    The " emergency " switch is actually a small lever on the bottom of the unit. The unit is in easy reach of my left hand..with the right hand on the wheel I would not even loose sight of the road. The unit is level with the bottom of the dash ... no problem, it's not down in the foot well.

  • paisanpaisan Member Posts: 21,181
    Gotcha, from your description it sounded real low, was just worried about your safety is all.

  • dee004dee004 Member Posts: 1
    I have an 05 F250 Super Duty CC 6.0L. Does anybody know where the connector is under the dash to hook my controller to? I received the connector with the truck and wired it to my new Prodigy controller but can't find the connector under the dash.
    [email protected]
  • stockdragracestockdragrace Member Posts: 1

    Thanks for the info on the 2007 Silverado brake controller wiring, VERY HELPFUL, I found all the wires as you stated including an orange one under the dash, in that same wiring harness, does the on/off light work on your controller when you apply the brakes without that orange wire being hooked up?
  • chrmdomechrmdome Member Posts: 107

    I have a Prodigy. The Prodigy has only 4 wires and does not use the orange wire. If I understand the Chevy wiring description, the orange wire is not used. The Prodigy goes on when you move the vehicle and turn on the engine and remains on until the power saver mode kicks in.... at rest , the Prodigy does not have any light display on its screen..until you start the vehicle and then it goes on automatically from movement, it is not wired through the ignition switch.

  • triki_dicktriki_dick Member Posts: 1
    I found this post!! GREAT!!

    Questions, you say fuses 65 + 70.... My GMC has a fuse in 65 and 70 is empty.

    Also, the power from thats under the brake booster, I only find 1 red/black wire. I asume this is correct, but I want to 100% make sure.

    And, where do I hook up the red/black wire. Is it on the front of the under/hood fuse box? Because you talk about small post,big post. Is there a difference.
  • geo9geo9 Member Posts: 735
    Check out this link with pics and the official GM
    tech bulletin with wire color chart for trailer
    brake controller install on 07 GM trucks !!!!

    Why the heck did GM do away with the plug n' play
    setup like the GMT-800s have???????????

    Sure glad my new GmT-900 3/4 has the built in factory
    controller ! :P
  • jklingel8jklingel8 Member Posts: 10
    I have an 07 Classic, and the wiring was a cake-walk; pigtail in glovebox, plug into harness at floor, and wire to Prodigy. The small "unused" wire is for illuminating the brake controller, which the Prodigy does not need. Keep the wire handy (and well insulated from grounding out) in case you need to illuminate anything, like the knuckle heads at GM who decided to not pre-wire the trucks any more. IDIOTS, I say, even if some folks were screwing the wiring up.
  • rheckrheck Member Posts: 5
  • aboo155aboo155 Member Posts: 2
    I have a 2001 silverado with the tow package. supposedly that has an electric brake wiring harness behind the instrument panel. does anyone know where this is?
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