Trailer Lights Issue

[Marc Marcantonio]

Last month I bought a new 2021 Yukon AT4 tow vehicle. When I hitched my 08 Ranger Z20 and plugged in the trailer lights, I noticed my trailer tail lights on both sides are rapidly and faintly blinking, nonstop. As long as I have my trailer lights connected to the vehicle, the lights blink even when all the power is shut off at the Yukon.

All trailer and vehicle lights work properly when activated, but the taillights just don't shut completely off when the vehicle is shut down. They keep blinking until I unplug the trailer light plug.

FYI, my Ranger Trail wiring has the 5 pin flat plug, and then I use a converter plug with a one foot cable to convert the flat plug to the round plug which goes into the vehicle. Any ideas? Maybe need to replace the converter cable?

[Team Dougherty]

Perhaps you converter cable in wired wrong. The round plug on your vehicle has an always hot 12v source. Maybe that is what is lighting your lights.

[CatFan]

Some vehicles have this issue. It's a combination of two factors. First is the system the vehicle uses to determine if it is connected to a trailer. It does this by sending very small pulses on the light circuit looking for a load. The second factor is LED lights on the trailer. They take such little power that the vehicle check pulses cause the lights to flash on. Do you have LEDs on the trailer?

[MikeF]

All trailer and vehicle lights work properly when activated, but the taillights just don't shut completely off when the vehicle is shut down. They keep blinking until I unplug the trailer light plug.

Look in your manual for the anti theft trailer feature.

Another useless GM brainchild starting on 2019 models and up.

So many people come running down to the ramp and say or yell out " your trailer lights are on"' when I launch at or before dawn.

I try and remember to pull my plug before launching and plug in before retrieval.

Reminds me of the old unsealed lights, bulb days

PIA

[Marc Marcantonio]

Some vehicles have this issue. It's a combination of two factors. First is the system the vehicle uses to determine if it is connected to a trailer. It does this by sending very small pulses on the light circuit looking for a load. The second factor is LED lights on the trailer. They take such little power that the vehicle check pulses cause the lights to flash on. Do you have LEDs on the trailer?

Yes, my Ranger Trail lights are LEDs. The new Yukon does have the "max trailering package" which I believe does have a trailer anti-theft feature, and also provides trailer tire pressures and temperatures. The Yukon knows when a trailer is connected, and it does a diagnostic test on all trailer lights, and when completed they check out as being okay. Then I go back and see the lights in rapid dim blink mode....

So what is the solution? I don't want to have to remember to always pull the trailer light plug and reinstall it before leaving the lake...

[Marc Marcantonio]

Look in your manual for the anti theft trailer feature.

Another useless GM brainchild starting on 2019 models and up.

So many people come running down to the ramp and say or yell out " your trailer lights are on"' when I launch at or before dawn.

I try and remember to pull my plug before launching and plug in before retrieval.

Reminds me of the old unsealed lights, bulb days

PIA

The new Yukon does have the "max trailering package" which I believe does have a trailer anti-theft feature, and also provides trailer tire pressures and temperatures. The Yukon knows when a trailer is connected, and it does a diagnostic test on all trailer lights, and when completed they check out as being okay. Then I go back and see the lights in rapid dim blink mode....

So what is the solution? I don't want to have to remember to always pull the trailer light plug and reinstall it before leaving the lake...

[MikeF]

So what is the solution? I don't want to have to remember to always pull the trailer light plug and reinstall it before leaving the lake...

Learn to embrace and live with all the new and wonderful features of the GM max tow package, including the blinking lights, while plugged in.

Seriously, none that I have found yet.


I have found my plug pulled out, laid out nicely across the trailer tongue, when retrieving the trailer from the lot.

Probably some good Samaritan thinking he was saving me from a dead battery at days end.


If you find a cleaver work around, please share with us and maybe even share with GM.

Good Luck

[Marc Marcantonio]

Has your battery run down from the trailer lights blinking so that your car won't start?

[MikeF]

Has your battery run down from the trailer lights blinking so that your car won't start?

Not yet and have not read or heard of anyone having a starting issue with this feature.

I have had a few trips where the truck and trailer have been hooked together for a week straight, with just a launch and retrieve run daily and less than a 1 mile run to and from the ramp.

The blinking light system has very minimal amp draw (probably milliamps), but is a bit taxing on the nerves until you get used to it and learn to ignore it.

[jstbass]

Hi Marc I have a 19 GMC Denali truck and mine does the same thing. Its the anti theft device for the trailer. It will detect the trailer on the vehicle And if the truck is locked and you try to unhook the horn will start blowing the lights will blink until you go and unlock it and reset the system. Personally I like it extra protection when at a hotel. And yes people tell me my light are on all the time. I am used to it now.

[Marc Marcantonio]

Hi Marc I have a 19 GMC Denali truck and mine does the same thing. Its the anti theft device for the trailer. It will detect the trailer on the vehicle And if the truck is locked and you try to unhook the horn will start blowing the lights will blink until you go and unlock it and reset the system. Personally I like it extra protection when at a hotel. And yes people tell me my light are on all the time. I am used to it now.

Thank you all for explanation and assurance. I will not worry about it any longer, but will embrace it instead. Good to know my trailer wiring and/or plug do not have a short in them. I sure do appreciate the help and advice here!

Having the trailer theft deterrent system could come in handy at some of the remote lakes around here frequented by tweakers.

[billnorman1]

Install a good padlock. You could experiment with a resistor in parallel with the brown wire and ground and see if the sensing device turns off.