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It should be possible. Get the correct antenna, run the cable up to the front of the car, and install an HD capable receiver module. I put in a 2016 radio and was able to keep the HD functions my 2014 came with.
It might be a little different as my MY doesn't come with HD radio like yours did. I think if you get an updated module from places like GM-navigation.com it makes the radio HD but wouldn't you need the HD antenna, as well?
I don't think the antenna is any different, only the Radio module is different. HD is broadcast "piggyback" on the standard FM frequencies...and you already have an FM antenna.
Last edited by ersatz928; May 13, 2019 at 03:44 PM.
I don't think the antenna is any different, only the Radio module is different. HD is broadcast "piggyback" on the standard FM frequencies...and you already have an FM antenna.
Now I'm really confused. I just went back and looked at the antenna schematics. It says the HD signal is shared with the XM antenna under the left front fender.
My antenna schematic labels this (the one mounted under the drivers side fender) the "HD/XM Digital Radio" antenna, which is for the Sirius Satellite radio, not the FM HD radio.
Last edited by ersatz928; May 13, 2019 at 06:44 PM.
This is the official GM diagram. U2K is XM satellite, U2M is XM + HD. U2Q is the European DAB system. U2M wasn't offered on 15-17, and on 2018 the HD radio RPO was changed to U2L, so....
The "HD" label in the GM schematic is not correct. HD radio is broadcast on the FM frequencies, and uses the T4L and T4R antennas (located behind the rear bumper cover). Trust me, the GM Service Manual has lots of typos....
From Wikipedia: HD Radio is a trademarked term for Xperi's in-band on-channel (IBOC) digital radio technology used by AM and FMradio stations to transmit audio and data by using a digital signal embedded "on-frequency" immediately above and below a station's standard analog signal, providing the means to listen to the same program in either HD (digital radio with less noise) or as a standard broadcast (analog radio with standard sound quality). The HD format also provides the means for a single radio station to simultaneously broadcast one or more different programs in addition to the program being transmitted on the radio station's analog channel.
Last edited by ersatz928; May 14, 2019 at 11:53 AM.
That's why I was confused. I always understood it to work the way you're describing it. The diagram made me second guess that.
I guess you could read the diagram a different way. U2K and U2M both include XM service. The same antenna is used for both RPOs, even though the HD portion of the U2M package has nothing to do with it.
That begs the question of why GM didn't offer HD in the 15-17 cars if the only difference was the radio receiver module.
The "HD" label in the GM schematic is not correct. HD radio is broadcast on the FM frequencies, and uses the T4L and T4R antennas (located behind the rear bumper cover). Trust me, the GM Service Manual has lots of typos....
From Wikipedia: HD Radio is a trademarked term for Xperi's in-band on-channel (IBOC) digital radio technology used by AM and FMradio stations to transmit audio and data by using a digital signal embedded "on-frequency" immediately above and below a station's standard analog signal, providing the means to listen to the same program in either HD (digital radio with less noise) or as a standard broadcast (analog radio with standard sound quality). The HD format also provides the means for a single radio station to simultaneously broadcast one or more different programs in addition to the program being transmitted on the radio station's analog channel.
There's a chance it could work. I'm using 2016/2017 software and hardware in my car. HD radio wasn't an option in those years. But my HD works fine. So maybe going backwards is possible too. I wouldn't install a newer radio without also upgrading the HMI, but it might be possible to install either a 2014 radio, or a 2015 radio from a different model that did offer HD.
I'd send an email to one of the companies that offers the HMI upgrade packages. They should know enough about the radio software to give you a better idea. The radio modules are relatively cheap compared to the HMI, so it shouldn't be too big a risk.
For what it's worth I upgraded the HMI and ACM modules in our 2015 Z06 last week primarily to obtain Apple Carplay. The bonus of doing the swap are FM HD radio channels also now working perfectly since the upgrade.
