HMI or radio issue?

Dustin10 · April 24

I have a 2018 GMC Sierra. My radio would not work when the temperature was really cold (negative temperatures) but as the truck would warm up the radio would start working again. As time went on warmer temperatures like 10, 15 and even 30 degrees would start to impact the radio. Same issue it wouldn’t work for 10-20 minutes until the truck was warmed up. Eventually the radio stopped working all together. When it quit working all together my front bumper sensors stopped working and so did the speed limit display in my dash. The back up camera worked and displayed on the screen the whole time. I brought it to the dealership today and they reset the radio with their computer but said I will eventually need a new radio. If it’s just the radio why would it impact the front bumper sensors and the speed limit display? They said one system going down can cause others to go down too. Anything else it could be and could the dealership be wrong thinking it’s just the radio? When I research online I’m seeing the HMI could be a more likely culprit. Both are expensive so I’d rather have more information before buying parts.

new battery, replaced the main ground from the battery and to the frame.

davester · April 24

it depends on what's wrong.

bad/failing solder joins can make or break connections based on changing temps, and if this happens on the computer data bus the truck uses, that can impact the ability for other computers to communicate. But, it could also just be a coincidence that the front sensors are having problems around when the radio is.

Dustin10 · April 24

1 hour ago, davester said:

it depends on what's wrong.

bad/failing solder joins can make or break connections based on changing temps, and if this happens on the computer data bus the truck uses, that can impact the ability for other computers to communicate. But, it could also just be a coincidence that the front sensors are having problems around when the radio is.

When they reset the radio module the front sensors started working again.. my friend works for the dealer and with their discount the radio is still $500+ without labor. I’d hate to pay for that then find out it is the HMI or something else. To me it just doesn’t seem like it’s a radio unit alone causing this.

MikeBMW · April 24

For what it's worth, Ive never experienced a bad HMI module.
I've installed many of these as I upgraded to a navigation HMI.
I still have two sitting on the shelf but they would have to programmed to your VIN which is what WAMS does.
If you find that to be the issue, I can send you one but, again, @GTPprix would need to program it.

newdude · April 24

11 hours ago, Dustin10 said:

I have a 2018 GMC Sierra. My radio would not work when the temperature was really cold (negative temperatures) but as the truck would warm up the radio would start working again. As time went on warmer temperatures like 10, 15 and even 30 degrees would start to impact the radio. Same issue it wouldn’t work for 10-20 minutes until the truck was warmed up. Eventually the radio stopped working all together. When it quit working all together my front bumper sensors stopped working and so did the speed limit display in my dash. The back up camera worked and displayed on the screen the whole time. I brought it to the dealership today and they reset the radio with their computer but said I will eventually need a new radio. If it’s just the radio why would it impact the front bumper sensors and the speed limit display? They said one system going down can cause others to go down too. Anything else it could be and could the dealership be wrong thinking it’s just the radio? When I research online I’m seeing the HMI could be a more likely culprit. Both are expensive so I’d rather have more information before buying parts.

new battery, replaced the main ground from the battery and to the frame.

Speed limit works off the navigation system. Which is...in the radio.

Park assist. The alert tones are handled via the radio. The tone not working won't disable the system though. The only things that will disable the park sensors is things related to those like a bad sensor or multiple sensors, wiring, bad module, etc.

Sounds to me like the radio is the issue.

A failed or failing HMI most commonly would have the radio changing screen pages on its own, radio source switching on its own, etc. You'd have a working screen but it will have a mind of its own. But everything would work still as far as the radio and what it does.

carkhz316 · April 24

The HMI also handles switching of the rear camera input/ output, so the fact that the backup camera works on demand generally rules out the HMI as well. If the HMI fails, you'll still have sound coming from the radio, but the infotainment will be blank or unresponsive. Typically, stations and volume can be controlled from the instrument cluster if that happens.

The radio, amp, HMI, CD player, and instrument cluster are on their own dedicated communication bus known as the Media Oriented Systems Transport, or MOST bus. It is fairly easy to diagnose with the proper tooling. GDS2 and some aftermarket scan tools will outline which 'node' or module (of the aforementioned components) are not working properly and help to isolate the defective module or circuit portion. The dealer should have been able to find this out without too much effort.

Edited April 24 by carkhz316