Expert Answers about GMC Acadia

• Troubleshooting No Running Lights On A Flat Towed 2011 GMC Acadia
• Hello Marv! I am happy to try to help you troubleshoot the wiring issues you are having on your 2011 GMC Acadia. This is an interesting issue you have described, and there are a few things you will want to check. First, we want to confirm that we do in fact have a solid running light signal coming from your RV. The running light circuit should be at the "11 o'clock" pin on the RV 7 way. We suggest going in with a wire tester like part # PTW2993 and verifying that there is power to the...
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• Trailer Lights do not Work with the Tow Ready T-One Harness # 118451 on a 2010 GMC Acadia
• The Tow Ready T-One Wiring Harness, # 118451, does not require any additional fuses or relays. As you said, this harness provides power to the trailer lights from the vehicles tail light circuits. The only time you would need to install a fuse is if one of the taillight fuses were blown on the vehicle. This would mean your taillights, turn signals or brake lights were not working on your Acadia. If you are positive that you have a good ground and the T connectors are installed correctly...
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• What Circuit Does Red Wire of Brake Controller Attach To
• I would hammer a little harder on what circuit they attached the red wire to of the brake controller. It was supposed to attach to a circuit that only has voltage when the brakes are applied. If they attached it to a random circuit and didn't verify it had voltage that would definitely be why.
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• Constant Power on Pins Inside 4-Way When Installing T-One Harness on a 2015 GMC Acadia
• I spoke to my contact at Tekonsha about the issue you are having with the T-One Vehicle Wiring Harness part # 118270 on your 2015 GMC Acadia. They said they have heard of this issue before but it is not very common. For starters, you will need to switch the orientation of the relays if they do not look like the ones in the attached photo. Unlike most relays, the pins are positioned in a way that will allow them to be installed incorrectly so you will need to check this first. If the relays...
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• No Brake or Turn Signals With Trailer Wiring Harness On a 2007 GMC Acadia
• I am not sure which exact trailer wiring harness you are using but if you have one that plugs into the factory tow package plug like the T-One Vehicle Wiring Harness part # 118384 for example then the issue you are having would lead me to believe that you are missing some fuses/relays or they are blown. I took a look in your owner's manual and it lists two fuses for the stop/turn signal lights, "LT TRLR STOP/TRN" for the left stop/turn circuits and "RT TRLR STOP/TRN" for the right stop/turn...
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• Brake Controller on 2020 GMC Acadia Only Sends Power to Trailer Brakes with Manual Override
• It sounds like you have a proportional brake controller, like the Prodigy P3 # 90195, installed on your 2020 GMC Acadia. Since a proportional brake controller uses an internal inertia sensor to help determine how much power to send back to the trailer brakes it won't send any power when you are sitting still. That's why you're able to apply the brakes with the manual override and not with the brake pedal. The lights for your trailer are actually on separate circuits from the trailer brakes...
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• Adjusting Power and Boost on Prodigy P3 Trailer Brake Controller 90195
• The braking force you feel when slowing your trailer with your Prodigy P3 # 90195 is determined by three individual settings: the power level set on the controller, the degree of boost set on the controller and also on the actual adjustment of the drum brakes on the trailer itself. The trailer's over-sensitive response to your braking action in the Acadia could be due to any of these, or a combination. Since you just recently purchased the Prodigy P3 from us (thank you!) and you are presumably...
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• Why Won't the Mounting Bracket on My Curt Hitch # C13293 Fit My 2020 GMC Acadia?
• I'm sorry to hear about your hitch! Given that your vehicle is a non-AT4 model 2020 GMC Acadia, one of the common issues people have with hitches is bending/bowing of the hitch during delivery. If the angle on the welded end of the driver's-side brackets does not match the frame rail, it does indeed sound like an issue with bending/bowing of the Curt Trailer Hitch - 2" # C13293. While we have not heard of the # C13293 not fitting your vehicle, bending/bowing is more common than people...
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• No Running Lights With T-One 4-Pole Harness # 118451 on 2009 Acadia XLT with Tow Package
• The wiring harness you referenced, T-One 4-Pole Harness # 118451 from TowReady, uses plug-and-play connections to your Acadia taillight assemblies to generate lighting signals for your trailer. This harness provides trailer lighting signals on its included 4-pole connector that are completely independent of any factory tow package wiring that may be in place. Please take a look at the linked video which shows installation of this harness in your same year/make/model vehicle. The written...
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• Trailer Running Lights Will Not Work with 2009 GMC Acadia XLT with Tow Package
• First you are going to want to make sure that the running light circuit is working on the trailer connector on the 2009 GMC Acadia. Use a circuit tester such as # PTW2993 to test the running light circuit. If it is not working, then check the vehicle owner's manual for the fuse location for the tow package running lights to check/change it. Also check the owner's manual for any relays that might be needed for the tow package wiring. I do not recommend tapping into the running light wire...
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• Blown Fuse on a 2020 GMC Acadia Causing Wiring Harness Malfunction
• It sounds like you are either missing a fuse or have blown it out. You are looking for fuse F11 in the rear compartment fuse box of your 2020 GMC Acadia. This would cause the reverse function to go out but not the other ones with the Tekonsha T-One Vehicle Wiring Harness for Factory Tow Package - 7-Way Trailer Connector item # 118276. I have linked a picture below that will help you find the fuse location. This fuse box is in your rear cargo area on the driver's side.
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• Hardwiring Brake Controller to 2017 GMC Acadia Troubleshooting White and Blue Wire Not Active
• Does the third brake light of your 2017 GMC Acadia still activate? Normally if the stoplight circuit on a GM vehicle stops working the issue is a blown third brake light fuse. The white wire with the blue stripe on a 2017 Acadia is supposed to be the stoplight circuit. I'd be willing to bet the fuse is just blown.
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• Troubleshooting No Trailer Turn/Brake Signals with 2007 GMC Acadia
• I do agree that the wiring issue you are experiencing is somewhere on your Acadia. You mentioned that the Acadia didn't come with the tow package but it does have the trailer wiring and hitch. This means you likely have a T-Connector wiring harness installed such as the Tekonsha # 118451 that plugs into factory ports behind the tail lights. What I recommend doing is checking the white ground wire coming from the harness. Make sure this is still securely attached to a clean, bare metal...
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• Troubleshooting Tekonsha T-One Trailer Harness Not Working on 2012 GMC Acadia
• The Tekonsha T-One Wiring Harness # 118451 that you ended up installing is the correct harness for your 2012 GMC Acadia and it will work whether or not you have the tow package so you made the right choice there. If you happen to have your trailer on hand, the first thing I recommend doing is simply hooking it up to the Acadia and plugging in your connectors. Sometimes those LED testers can be a little finicky so it's possible that the harness works perfectly and the tail lights on the...
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• Tail Lights on 2008 GMC Acadia Stop Working when Trailer is Connected
• Let's start with the easy stuff. Make sure the white ground wire on harness # 118451 is attached to a clean bare metal surface on your 2008 GMC Acadia. There can be no coating or paint and it works best if the wire is grounded by itself. If that doesn't help then what is probably going on is the trailer lights draw more power than the vehicle wiring system can handle. You can test this by removing the connections to some of the lights. Then, if everything else starts working, including...
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• Troubleshooting Brake Controller Installation For 2013 GMC Acadia
• I would start by checking to make sure each wire is connected in the correct location by function not by wire colors because colors can vary. Next, I would make sure ground wires are firmly connected and secured. After that, I would check all your wires with a circuit tester like Item # PTW2993. Finally, I would double check fuses and relays to make sure they are working. I am attaching articles on brake controllers and troubleshooting that might help.
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• Tekonsha P3 Installed in 2014 GMC Acadia Won't Power Up
• Check the fuse box in the engine compartment, it's on the passenger side. Remove the cover, and look for the fuse location labeled '*' or 'TRLR BRK' as shown in the diagram I've provided. Install a 30 amp fuse or replace it if it's blown. I think what might have happened is that although your OEM brake pigtail might have the same wire colors except for the gray wire, the wires do NOT match up color for color to the brake controller wires. On your pigtail, the red wire is for 12-volt power,...
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• Troubleshooting Trailer Connectors That Do Not Pass Running Lights or Turn Signals
• The best way to troubleshoot trailer wiring is to first test your Acadia's 4-pole WITHOUT the Curt adapter. This will let you know if the signals are reaching the adapter. Even though the LED test lights may come on, since these take so little power to light up it could be that there is a small residual voltage in the system that is causing them to illuminate even when no actual running light or turn signal is reaching the adapter. You can use a tester like the # PTW2993 to check the Acadia's...
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• Troubleshooting Left Stop/Turn Signals on Trailer Towed by 2007 GMC Acadia
• You have already started the troubleshooting process to find the cause for your trailer's left-side turn and brake lights not working. Since another vehicle has no issue with this trailer this does tend to suggest that the issue is on the Acadia. Since both 4-pole and 7-way trailer wiring setups combined the left stop and turn signals onto one wire, typically a yellow one, what I suggest is that you start a close inspection of this circuit/wire at the trailer connector itself. You can...
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• Troubleshooting Trailer Turn Signals Malfunctioning with 2007 GMC Acadia with 4-Pole Wiring
• The problem you describe, both trailer turn signals activating when either turn signal on the Acadia is engaged, is typically a grounding issue. Since you have already re-worked both the vehicle and trailer main grounds to ensure both are solidly connected to clean bare metal surfaces, then the most likely cause for the problem is either a bad wiring harness on the Acadia or some issue with your adapter. I could not find purchase history to let me see the specific wiring harness and adapter...
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