Thread: Map conflict? on SDHC memory card

On a Nuvi 1490t I installed a new 16GB memory card and loaded a number of maps in the \map directory. There are three topos in the directory and a small file (74MB) City Navigator NT America with 3 states loaded. The topos include two 24k US West Coast maps, and one 100K US topo. One map, the US West 24K topo from public source (2.6GB), does not show up in the garmin map info even if all others are deselected. This map works fine if it is the only topo on the card.

Experimenting and changing the img extension to imo on various maps revealed that if the other (Garmin 24k US West 2009 4.0GB) extension is changed to imo, the public source US West 24k is recognized and works with all other maps on the card.....

This implies there is some issue having both 24k topos loaded on the card even if they are not selected, and the public source 24k is not recognized by the nuvi with the Garmin US West 2009 img file in the directory. The Garmin US West 2009 topo does show, but the public source mapset does not.....

The only other detail I can identify is the public source mapset is a NW and SW mapset combined, and even though it is one file, the nuvi recognizes it as two maps; NW 24k topo and SW 24k topo.....These are the two that do not show up if the Garmin US West 2009 topo img file is in the directory.

The benefit of the three topos is that they sometimes describe different features, so if in an area for instance, one can find forest roads or labels on one but not on the others.

Oddly on another 8GB card both 24k topos are recognized. This card has some other central american maps, no 100k topo or City Navigator....


Any ideas what would cause this apparent conflict?
Suggestions?
Thx