At constant static on low band 47.10 in 2020 GMC sierra

[Rickplummer56]

The other thing I tried in relationship to my brake lights was I turned on the 4 way flashers thinking the noise would go on and off with the lights as they do when I step on the brake. Nope that changed nothing ?

 

[mmckenna]

Sure sounds like something in/on your truck. One option is to do the key on/engine off thing so you can hear the noise, and then start pulling fuses one at a time and see which one makes it stop. That'll at least narrow it down to a specific circuit, although there may be more than one thing fed off the fuse.

 

[mmckenna]

Does this truck have the electric trailer brake controller either standard on the dash, or added in later?

 

[Rickplummer56]

Sure sounds like something in/on your truck. One option is to do the key on/engine off thing so you can hear the noise, and then start pulling fuses one at a time and see which one makes it stop. That'll at least narrow it down to a specific circuit, although there may be more than one thing fed off the fuse.

I did that today. Pulled every fuse. No change

 

[Rickplummer56]

It does have an automatic factory trailer brake control. Have tried shutting it off and on even hook a trailer up no change

 

[mmckenna]

I think there are a couple of fuse blocks in those trucks. I think one under the hood and one on the passenger side of the dash board, I think you open the passenger door and it's behind a panel on the side of the dash.

 

[Rickplummer56]

Ya I ran out of time. I did all the ones under the hood. I will try the others tonight or tomorrow

 

[cmjonesinc]

When I worked for what was previously FCA (Dodge Jeep etc) we had what were called 'Star' cases. It was where a technician can escalate out of the ordinary issues to a factory technical advisor for assistance. We could search through previous cases for symptoms and already known fixes. You might try calling or having one of your motor fleet mechanics call the GM dealer where the truck came from. I'm sure they have a similar program. A quick search in their system may save some head scratching or point you in the right direction. Best of luck getting it fixed. I know those problems can be a real pain to figure out sometimes.

 

[Rickplummer56]

There has to be one that stops it I would think

 

[Rickplummer56]

When I worked for what was previously FCA (Dodge Jeep etc) we had what were called 'Star' cases. It was where a technician can escalate out of the ordinary issues to a factory technical advisor for assistance. We could search through previous cases for symptoms and already known fixes. You might try calling or having one of your motor fleet mechanics call the GM dealer where the truck came from. I'm sure they have a similar program. A quick search in their system may save some head scratching or point you in the right direction. Best of luck getting it fixed. I know those problems can be a real pain to figure out sometimes.

Good idea we buy a lot of trucks big and small from this dealer do I will try them. Thanks

 

[Rickplummer56]

Took the antenna off the mount. Noise stops

 

[mmckenna]

OK, so noise coming in via the antenna.

Question remains, is the noise being generated by the truck, or is it something local to you. Pulling the fuses would be a good thing to try.

 

[merlin]

Your truck brain is generating all that noise. Probably, the anti-lock brakes are reducing that noise.
You need a filter in the power cables close to the radio.
If your antenna does not have a DC ground path, a filter there may help or change to a type of antenna like base loaded with a DC ground path.
Air bags are another big offender for generating noise, as are the light bars.
I do have the LED fog lights. if you have LED head lights, try turning those on, see if anything changes.
I am using a Motorola 24-80371A05 coil with a 44" whip and very little noise.
Larsen NMO40C is nearly an exact replacement.

 

[ladn]

Does the truck have a brake light on the back of the cab, above the bed?
Since we're running low on options, can you remove the bulb/led from that light?

 

[Rickplummer56]

Your truck brain is generating all that noise. Probably, the anti-lock brakes are reducing that noise.
You need a filter in the power cables close to the radio.
If your antenna does not have a DC ground path, a filter there may help or change to a type of antenna like base loaded with a DC ground path.
Air bags are another big offender for generating noise, as are the light bars.
I do have the LED fog lights. if you have LED head lights, try turning those on, see if anything changes.
I am using a Motorola 24-80371A05 coil with a 44" whip and very little noise.
Larsen NMO40C is nearly an exact replacement.

Thank you

 

[Rickplummer56]

Does the truck have a brake light on the back of the cab, above the bed?
Since we're running low on options, can you remove the bulb/led from that light?

It does and I will try that Thanks

 

[Rickplummer56]

OK, so noise coming in via the antenna.

Question remains, is the noise being generated by the truck, or is it something local to you. Pulling the fuses would be a good thing to try.

Pulled every fuse. No difference. It happens all over not just local