No GPS Signal due to OnStar or XM

[tmalak]

Hello,

I am a new owner of a TomTom XXL 540 TM that I purchased in December. Upon opening, everything functioned correctly in the house and I was able to update the maps etc.

However, once I put it in my vehicle, a 2006 Chevy Tahoe with OnStar and XM Radio, I was never able to obtain a GPS signal. TomTom support stated it needed a GPS fix. So, after 7 calls, multiple downloads and even formatting the unit that would never obtain a signal, I received a new one.

I began to do my own "testing" with the new one and found that I had a GPS signal when my vehicle was not running. As soon as I started it, I lost the signal. No different positioning of the unit would correct it. When I turned off the vehicle and removed the key, the GPS signal returned. The same unit works in all of our other vehicles -- none of which have OnStar or XM radio. I contacted TomTom support again and immediately they wanted me to download "fixes". I refused and went through my story again. Finally, I was put on hold and the technician returned to inform me that it was the OnStar (even though I do not have active service). They suggested an external antenna -- but no longer make or sell them for this unit.

So, my bottom line question to the experts is: 1.) Can this situation be resolved with an external antenna? 2.) If so, which model, manufacturer, etc, is recommended? 3.) Will an external antenna interfere with the lifetime maps and traffic updates?

Thank you in advance for any help you can provide!! Tanya

 

[mikealder]

I doubt an external GPS aerial is going to be much use in this instance, for a start there is nowhere to plug it in.

Its possible the kit in your car is interfering with the GPS signal, can you try a different GPS unit in the same car and see if that is also affected. If you find other GPS devices don't work in the same car then its a case of trying to issolate whats causing the issue, what happens if you turn off the OnStar or XM units - Mike

 

[mvl]

XM is receive-only, so my guess is that it is OnStar with the interference. Call up the dealer, perhaps there's a TSB or software update that prevents the interference.

Or, if you're not using OnStar, see if there is a fuse that you can pull to disable OnStar without bothering anything else.