Humming Noise In Rear After Shut Off

[cabledude]

Have been away from the forum for awhile but just got a different truck, a 2020 Sierra 1500 so I'm back. I've searched for this question but can't find results.  Several times today, first times since I've had it, I got out and heard a humming noise coming from the rear of the truck. The only thing I can think of is fuel pump. M y questions are why haven't I heard it before and why is it running after shut off not prior to starting. Any info is appreciated. My 2018 Sierra never did this.

[GETGONE]

It's normal. There's a bunch of other new stuff in the T1 platform the older trucks didn't have. I was concerned when I first got mine but then I read the owners manual and it mentions the various things that still run after the truck is shut off. The HVAC system closes itself up and I believe the radiator shutters also cycle. I know every time I open a door after it's sat it starts making noises.

[cabledude]

Thanks for the info.

[Enough]

Don't stay in the truck too long after shutting it down. Mine sounds like there is someone building an interstate highway behind the dash 5 minutes or so after shut down. Bumps, clicks, buzzing, whistling, etc..

 

I just cringe and walk away !

[cabledude]

That is so strange. Then yesterday the Service Park Brake light and message came on. Tried cycling the button several times and stayed on, but 15 minutes later went back off. I'm not sure what to worry about and what to just disregard. 

[cabledude]

Took the truck in for a oil change today and have the park brake light checked out, which of course wasn't doing it at the time.  Luckily as the service manager got in to move it, it started making the humming noise and the service brake screen came on.  Turns out, the noise in the rear was the brake system.  Apparently someone had put new rear brakes on, there is a sensor to indicate when the brake shoes are worn, whoever did it didn't put the sensor back in and just left the wire hang.  It was somehow keeping the park brake from working.

Now if I could get the TPMS sensors working.........

[GETGONE]

If they didn't put the brake pad sensors in, does it have different wheels and tires? Maybe they didn't put the sensors in either or didn't put the correct frequency ones in. They should pair with the cheap $10-15 generic tool on ebay or amazon.

[cabledude]

Build sheet shows the truck should have had 20"  wheels but had 18' wheels, couldn't find out why.  My thought also, that maybe it wasn't the correct frequency, I don't quite know how the reading tools work, I would think they could determine what frequency they are, can't imagine 4 sensors would go bad.  The dealer is saying once a sensor is programmed it can't be reprogrammed for a different vehicle, not sure if that is correct or not.

 

[GETGONE]

Dealer is full of crap. I've swapped sensors between vehicles with no issues. Bought a set of used wheels with sensors and paired them just fine with my 08 Avalanche. Unfortunately the T1 trucks changed to 433mhz from 315mhz so you can't swap sensors from older trucks to new ones.

[GMCustomerService]

On 10/22/2022 at 10:56 AM, Enough said:

Don't stay in the truck too long after shutting it down. Mine sounds like there is someone building an interstate highway behind the dash 5 minutes or so after shut down. Bumps, clicks, buzzing, whistling, etc..

 

I just cringe and walk away !

This is certainly not what we like to hear, Enough.  Please know, customer satisfaction is extremely important to us. Our team would be more than happy to take a closer look into the concerns with your truck. To do so, please send an email to [email protected] with ATTN: Enough/GM Trucks in the subject line.

Please include your contact information, VIN, a brief description of your concern, and the name of your preferred dealership. We look forward to hearing from you. To learn more about GM’s privacy policy, please visit https://www.gm.com/privacy-statement.html.
 
Privacy Statement | General Motors
Your privacy is important to General Motors. This Privacy Statement addresses the personal information GM collects and how GM handles that personal information.
www.gm.com
 

[cabledude]

So, a follow up on this. Continued to have issues with the Service Park Brake screen showing up and having squealing noise coming from the rear of the truck.  Was back at the dealer this week and had them check again.  They said they tested all the wiring to each wheel and the brakes are ok, it has to be the Brake System Control module.  Has anyone else had this affect the park brake?  This is a $560 part at the dealer plus labor to install.  Wondering if I can get a aftermarket one or even a cheaper OEM replacement and install it myself, but can't find much information about where it is located or how hard it is to install.  Any info appreciated.

 

[Oscar Winner]

On 10/22/2022 at 10:56 AM, Enough said:

Don't stay in the truck too long after shutting it down. Mine sounds like there is someone building an interstate highway behind the dash 5 minutes or so after shut down. Bumps, clicks, buzzing, whistling, etc..

 

I just cringe and walk away !

Mine does too. I work on I-95 reconstruction, so it's double for me. ha ha

 

The relays behind the dash are loud too. They start clicking like the old arrival board at the train station.

 

[GMCustomerService]

On 2/6/2023 at 2:57 PM, Oscar Winner said:

Mine does too. I work on I-95 reconstruction, so it's double for me. ha ha

 

The relays behind the dash are loud too. They start clicking like the old arrival board at the train station.

 

This is certainly not what we like to hear, Oscar Winner.  Please know, customer satisfaction is extremely important to us. Our team would be more than happy to take a closer look into the concerns with your 2020 GMC Sierra 1500. To do so, please send an email to [email protected] with ATTN: Oscar Winner/GM Trucks in the subject line.

Please include your contact information, VIN, a brief description of your concern, and the name of your preferred dealership. We look forward to hearing from you. To learn more about GM’s Privacy Policy, please visit https://www.gm.com/privacy-statement.html. The information you provide may be monitored and recorded and is subject to the GM Privacy Statement.
 
Privacy Statement | General Motors
Your privacy is important to General Motors. This Privacy Statement addresses the personal information GM collects and how GM handles that personal information.
www.gm.com

[GMCustomerService]

On 2/6/2023 at 2:57 PM, Oscar Winner said:

Mine does too. I work on I-95 reconstruction, so it's double for me. ha ha

 

The relays behind the dash are loud too. They start clicking like the old arrival board at the train station.

 

This is certainly not what we like to hear, Oscar Winner.  Please know, customer satisfaction is extremely important to us. Our team would be more than happy to take a closer look into the concerns with your 2020 GMC Sierra 1500. To do so, please send an email to [email protected] with ATTN: Oscar Winner/GM Trucks in the subject line.

Please include your contact information, VIN, a brief description of your concern, and the name of your preferred dealership. We look forward to hearing from you. To learn more about GM’s Privacy Policy, please visit https://www.gm.com/privacy-statement.html. The information you provide may be monitored and recorded and is subject to the GM Privacy Statement.
 
Privacy Statement | General Motors
Your privacy is important to General Motors. This Privacy Statement addresses the personal information GM collects and how GM handles that personal information.
www.gm.com

[It's Tim]

On 2/5/2023 at 9:30 PM, cabledude said:

This is a $560 part at the dealer plus labor to install.  Wondering if I can get a aftermarket one or even a cheaper OEM replacement and install it myself, but can't find much information about where it is located or how hard it is to install.  Any info appreciated.

How many Millions do you think you'll be on the hook for when your third world brake job fails and you kill someone? Don't worry about your insurance coverage, they cancel your policy as soon as they find out.

 

Don't get me wrong... I'm pround to be a cheapskate but a vehicles brake system is something I will absolutely not cut corners on to save a buck. The fact that you are apparently operating a vehicle with suspect brakes is worrisome all in itself.

Edited February 8, 2023 by It's Tim