Trailer lights flashing

[plbass]

I have a 2020 GMC Sierra xlt. Whenever I park my boat trailer and turn off truck the trailer LED tail lights flash every 10 seconds. Any ideas on what is causing this?

[JJ461]

This is normal, it is stated in the owners manual on page 312.

 

"When a trailer is connected and the ignition is off, the Trailering App System will periodically pulse
the lighting circuits of the trailer to verify it is still connected. The trailer lights may periodically flash as a result of this trailer connection detection. These flashes may be more visible in dark ambient light environments. The flashing or flickering lights are a normal condition and the Trailering App System has built-in protections to prevent the battery from draining. When Theft Alert is also enabled
the frequency and pattern of this flashing will change."

Edited October 5, 2021 by JJ461

[Mudcon]

Yea mine does it too, it is the truck making sure the trailer is still connected. 

[SVG]

Completely normal as stated above. First time I saw it happening I thought WTF??

[Chris Callanan]

I've seen reports of folks with dead batteries in the morning though - so I unplug the trailer overnight just in case

[SVG]

10 hours ago, Chris Callanan said:

I've seen reports of folks with dead batteries in the morning though - so I unplug the trailer overnight just in case

I don't have any current facts to back up my position at the moment but I'd be shocked if the trailer monitoring system draws that much power to make a good battery discharge that much.

 

One thing to remember, there is a trailer alarm setting that will set off the alarm if someone disconnects your trailer, presumably in an attempt to steal it.

Edited October 7, 2021 by SVG

[JJ461]

On 10/7/2021 at 10:19 AM, SVG said:

I don't have any current facts to back up my position at the moment but I'd be shocked if the trailer monitoring system draws that much power to make a good battery discharge that much.

 

One thing to remember, there is a trailer alarm setting that will set off the alarm if someone disconnects your trailer, presumably in an attempt to steal it.

This is a feature I found out that the truck had at about 10:00 one night when I decided to unplug the trailer after the truck was locked... BTW the key fob was in the house, wasn't popular with the neighbors that night.

[Tmb]

I, too, have this situation with my 2019 Chevrolet Silverado. When my truck is turned off, the trailer lights on my horse trailer continue to flicker repeatedly every 10-15 seconds forever. I’ve resorted to unplugging the trailer to avoid any draw on my battery. 
NEW: I read not to long ago on this forum site that GM had come up with a fix. Some type of new computer module? My Chevy dealership had never heard of it so I had to furnish them the #specs from the Forum article I had read. It’s as yet, not a formal recall. Anyone know any more news on this issue?

[SVG]

Here is the page from my 2021 owners manual that talks about the trailer sensing. It says there is battery management software to protect the battery from discharging.

 

Maybe earlier year trucks don't have this feature? Not sure.

 

 

2021-gmc-sierra-1500-owners-manual copy.pdf

[Mudcon]

On 10/7/2021 at 11:19 AM, SVG said:

I don't have any current facts to back up my position at the moment but I'd be shocked if the trailer monitoring system draws that much power to make a good battery discharge that much.

 

One thing to remember, there is a trailer alarm setting that will set off the alarm if someone disconnects your trailer, presumably in an attempt to steal it.

I have left mine plugged in for a week on vacation without cranking my truck at all and did not have a problem with it cranking.  It was nice to have them flash as extra security to let people know or possibly think it might be armed and not try and steal it.  We were riding atvs and from top of the mountain at night I could see my truck flash down where it was parked. Pretty neat. 

[carlosh]

On 10/12/2021 at 1:15 PM, Tmb said:

I, too, have this situation with my 2019 Chevrolet Silverado. When my truck is turned off, the trailer lights on my horse trailer continue to flicker repeatedly every 10-15 seconds forever. I’ve resorted to unplugging the trailer to avoid any draw on my battery. 
NEW: I read not to long ago on this forum site that GM had come up with a fix. Some type of new computer module? My Chevy dealership had never heard of it so I had to furnish them the #specs from the Forum article I had read. It’s as yet, not a formal recall. Anyone know any more news on this issue?

They performed the tsb and plug fix on mine. Now lights only flicker on every 45 minutes or so

[Mike_F]

Quote

They performed the tsb and plug fix on mine. Now lights only flicker on every 45 minutes or so

carlosh

 

Do you have the numbers for the TSB and plug fix.

 

My dealer is clueless or lazy or maybe both, but definitely useless at this point.

 

Thanks