[Blasirl]

Yes. Attached is a pic of mine, in case there are other types.

If I understand correctly, this antenna does XM as well as AM and FM. If that's so, then there has to be some sort of low noise amplifier (LNA) in or near the antenna base for the XM. I'm not an RF guy - I can barely spell it - but what I've picked up over the years is that, for satellite radios such as XM, the RF amplifiers need to be right at the antenna. If that's the case here, I'm wondering if your amp is/was bad.

But, without having torn into it, I'm speculating for now. Interestingly, my Haynes has two radio drawings, but neither show an amp on the coax - don't know what to make of that.

As for mine, looking at the antenna, I see a couple spots where moisture could get in there to affect it. But I need to take it apart in hopes of confirming that.

Doug

.

XM works fine, just AM/FM is an issue. As for antenna types there seems to be at least two types. I have the larger of the two on my 2014.

 

[plano-doug]

XM works fine, just AM/FM is an issue. As for antenna types there seems to be at least two types. I have the larger of the two on my 2014.

I studied the Haynes a bit more yesterday. They list two radio types, 1) with graphic display, and 2) with navigation or color display. For 1, it shows two coax lines coming into the head unit. For 2, it shows 3 lines. This implies multiple antennas in both cases. But the text in the chapter covering the antenna only mentions one.

Perhaps there are two signals coming off the roof mast, maybe one for AM-FM, and another for XM, with an amp in-line.

Looking at the rear window defroster grid, I don't see the usual extra antenna grid I see on my Impalas, so I was thinking the rear window is not part of the antenna system. (But maybe it still is.)

For the case of 3 wires, I'm thinking there has to be another antenna somewhere.

I need to dig into mine, but it's too cold out today. It can wait

Doug

.

 

[Blasirl]

I studied the Haynes a bit more yesterday. They list two radio types, 1) with graphic display, and 2) with navigation or color display. For 1, it shows two coax lines coming into the head unit. For 2, it shows 3 lines. This implies multiple antennas in both cases. But the text in the chapter covering the antenna only mentions one.

Perhaps there are two signals coming off the roof mast, maybe one for AM-FM, and another for XM, with an amp in-line.

Looking at the rear window defroster grid, I don't see the usual extra antenna grid I see on my Impalas, so I was thinking the rear window is not part of the antenna system. (But maybe it still is.)

For the case of 3 wires, I'm thinking there has to be another antenna somewhere.

I need to dig into mine, but it's too cold out today. It can wait

Doug

.

I think the XM, the OnStar and then the radio all have different types of antennas. I think newer models have combined the XM and OnStar.

The two types of "radios" make no difference. There are some excellent threads by @StLouisCPhT, @dhpnet and @modalita among others on upgrading to the Navigation and Non-navigation MyLink systems. I do not remember anything being required be done to the antenna system with the exception of the GPS antenna which I think is the OnStar antenna.

Robert

 

[plano-doug]

I think the XM, the OnStar and then the radio all have different types of antennas. I think newer models have combined the XM and OnStar.

The two types of "radios" make no difference. There are some excellent threads by @StLouisCPhT, @dhpnet and @modalita among others on upgrading to the Navigation and Non-navigation MyLink systems. I do not remember anything being required be done to the antenna system with the exception of the GPS antenna which I think is the OnStar antenna.

Robert

Thanks. BTW, I should have said the Haynes manual had "2 schematics" rather than "two radio types".

Looking at parts on the web (gmpartsdirect.com), I see there are multiple antenna cables shown, some with two connectors on one end, indicating multiple bands. So I can maybe explain 2 of the coax inputs, but still haven't ID'd the 3rd one.

Doug

.