I have the the 478C (276 w/xm stuff and marine) and I loaded the topo stuff and i thought that all topo was not route-able. Guess I was wrong. But I will have to test that today !!
shown on my map info page.
TOPO U.S. 24K West Released: March, 2009 Version: 2.00 (most current version according to Garmin website)
TOPO U.S. 100K Topo 100K Released: March, 2009 Version: 4.00 (most current version according to Garmin website)
CN North America NT 2013.10
US Marine Detail map g2 v3.50
AMR standard autoroute basemap, NR
my PC says:
Topo US 2008 Version 4.00
Topo US 24K West Version 2.00
CN North America NT 2013.1 version 16.10
So I set mine in sim mode.
Confirmed. 2008 topo will not route on trails on my 478
using my 2009 24k, I routed myself to a remote place, then selecting "menu", then "map info" then I checked "topo 2008" then unchecked "24K"......the route was still there. but in my case/location some of the road was not on that map. But it did seem to eliminate some of the contour clutter. Oddly enough, my CNNANT 2013.10 had that trail on it anyway.
So I just might route using 2009 24k, OR CNNANT then change over to 2008 topo to declutter the 24k OR populate the CNNANT the screen a bit.
Just to let some of the new folks know that in the 276/478 series (maybe others?) that the order that is seen on the "map information" page, the top one is the primary map and sets an order of precedence. So just in case I did not word that correctly... if you have CNNANT on the top and then topo 2008 and then topo 24k under that and they are all checked. You will only view CNNANT. Uncheck that top one and the Topo 2008 will be viewed. hmmm hope that made sense.
Anyway I learned something from Yellow Pig, thanks for asking Garmin