06 trailblazer

If the after-market remote start/keyless unit is installed properly, the factory keyless entry will continue to function normally.  

Being as you will need a Passlock2 bypass for the remote start to work, why not get a combo unit that will handle the locks and factory alarm ( if equipped ) among other things, too?  Here is one option from DEI :  http://www.xpresskit.com/product.aspx?productid=125  There are other choices available from Fortin (   https://ifar.ca/en/vehicles/chevrolet/trailblazer/2006/ )  and iDatalink ( http://www.idatalink.com/support/helpdesk ).

I'd highly suggest using the XK01 bypass module with a Viper alarm that has the D2D connection. I just recently installed a remote start/alarm Viper 5901 with this XK01 on a 07' Trailblazer and it saves a lot of connections by using the data wire from your OBD2 plug. It also has extra features like window rollup, heated seats and rear defogger at a certain temperature.

Yes, thats the idea. This is my first go round with the XK01 and the temperature hasn't dropped below freezing yet. It is suppose to get cold next week, I'm real curious if its going to work properly. :)