Rear window defroster buzzing

Daryl Casey · January 25, 2021

2020 Sierra SLT

This morning I noticed a buzzing noise coming from the rear of the cab. The sound came from the right bottom of the rear window. The buzzing stops when I turned the rear defroster off. Turned the rear defroster back on, the buzzing started again.

Has anyone else had, or noticed, this problem? I tried to find a connecter to see if it was loose but couldn't find it. I don't think it's affected the performance of the defroster, at least not yet. I figure it'll require a trip to my dealership's service department, which I'm not a huge fan of.

Thanks for your time,

DC

redwngr · January 25, 2021

I'd be getting it looked at, and I'd avoid using it until after.

Daryl Casey · January 25, 2021

24 minutes ago, redwngr said:

I'd be getting it looked at, and I'd avoid using it until after.

absolutely.

I have disabled the defroster from automatically coming on with remote start and also made an appointment with the local dealership.

S Schultz · January 30, 2021

Would love to know what you find out. My 2020 RST just just started doing this same thing three days ago. Same spot too - passenger side right above the rear seat. Currently have 7000 miles on the truck. I have only noticed it in the morning when the temp has been about 35 degrees. Doesn't seem to be doing it later in the day. No idea if temp has anything to do with it.

If you get yours fixed soon, can you let me know what was found? I'll get mine in at some point, but it's always a hassle to take it to the dealer!

Thanks!

Abiker21 · January 31, 2021

On 1/25/2021 at 11:24 AM, Daryl Casey said:

absolutely.

I have disabled the defroster from automatically coming on with remote start and also made an appointment with the local dealership.

The buzzing is electricity arcing. Luckily it will be under warranty for you. There is a recall but it only covers vehicles in certain cold weather areas. Canada made GM recall all trucks with the sliding rear windows with defrost.

redwngr · February 1, 2021

On 1/29/2021 at 11:33 PM, S Schultz said:

Would love to know what you find out. My 2020 RST just just started doing this same thing three days ago. Same spot too - passenger side right above the rear seat. Currently have 7000 miles on the truck. I have only noticed it in the morning when the temp has been about 35 degrees. Doesn't seem to be doing it later in the day. No idea if temp has anything to do with it.

If you get yours fixed soon, can you let me know what was found? I'll get mine in at some point, but it's always a hassle to take it to the dealer!

Thanks!

If it's arcing and starts a fire, that will be alot more hassle than taking it in to get repaired....

Abiker21 · February 1, 2021

13 hours ago, redwngr said:

If it's arcing and starts a fire, that will be alot more hassle than taking it in to get repaired....

The arcing can produce a localized heat source and make the window explode. I have video of mine smoking before I pulled the fuse and submitted it to the .gov. They won't reply unless it becomes a recall.

DBCasey851 · February 3, 2021

On 1/29/2021 at 11:33 PM, S Schultz said:

Would love to know what you find out. My 2020 RST just just started doing this same thing three days ago. Same spot too - passenger side right above the rear seat. Currently have 7000 miles on the truck. I have only noticed it in the morning when the temp has been about 35 degrees. Doesn't seem to be doing it later in the day. No idea if temp has anything to do with it.

If you get yours fixed soon, can you let me know what was found? I'll get mine in at some point, but it's always a hassle to take it to the dealer!

Thanks!

Will do

S Schultz · February 4, 2021

On 2/2/2021 at 5:34 PM, DBCasey851 said:

Will do

I’m taking mine in next Monday!

Daryl Casey · February 9, 2021

My dealerships service dept is very backlogged due to a COVID outbreak. Not sure when I'll be able to get my truck in for this issue, but please share what you find out with us here!

S Schultz · February 9, 2021

7 hours ago, Daryl Casey said:

My dealerships service dept is very backlogged due to a COVID outbreak. Not sure when I'll be able to get my truck in for this issue, but please share what you find out with us here!

Well, my dealer can't find anything wrong. My defroster was buzzing/arcing real bad on Saturday. That afternoon, I happened to open the rear sliding window. The problem has not happened again since doing that. Have you dried cycling your window by chance? Not even sure that's what caused it, but I had a feeling that's what the dealer would say when I dropped it off. They couldn't duplicate the problem, and could not locate any service bulletins related to it. Hopefully it doesn't happen again, but it's documented if it does. Good luck with yours.

Daryl Casey · February 10, 2021

I'll definitely give that a try. We've got an ice storm headed our way and the rear defroster would be nice to have! Thanks for the update.

Fairfax · February 12, 2021

My 2020 Ram 1500 is doing the exact same thing. Definitely sounds like arcing! Cycling back glass has no effect.

Bob E · March 10, 2021

I had this happen to my 20 RST. I noticed there was a small leak and there was water coming off the track for the sliding window and running down the glass across the wires. The wires were really hot. I assumed it was the water sizzling on the wires because it only did it some of the time. Dealer took it in and replaced the window. Just got it back today so i'm hoping that solved it.

Ed/2020RST · April 7, 2021

On 1/31/2021 at 12:39 PM, Abiker21 said:

The buzzing is electricity arcing. Luckily it will be under warranty for you. There is a recall but it only covers vehicles in certain cold weather areas. Canada made GM recall all trucks with the sliding rear windows with defrost.

I believe you are 100% correct. There seems to be a conductivity issue. I bet if you look closely at the area the buzzing is coming from a small arc can be seen at night and maybe even a small burnt spot!!!