The Dowsing Machine (not map) is a Pokegear app that detects hidden items in grass or some other places. When you go to grassy areas that has empty spots, click A on them, maybe you will find an item.
This is the same for rocks! Click on them on all sides. You should use the Dowsing Machine first to not waste time. The Dowsing Machine screen appears on your bottom screen.
The dowsing machine is a poketech app which scans the ground for hidden items. It is app no.7.
You get the Poketch Dowsing Machine from Rowan's assistant on Route 207 after getting the Bicycle. This is on Pokemon Diamond and Pearl by the way...
Use the dowsing machine. Its near the entrance to the park.
it's not in route 207 dawn gives it to you
There is a map in the Pokemon Diamond/Pearl Guide Book.
if you want the dowsing machine app, in diamond and pearl, you can find it when you arrive at route 206 from your childhood friend (Dawn/Lucas). the dowsing machine is like the itemfinder, it allows you to find hidden items. if you want to find the marking map, the president of the poketch company will give it to you when you talk to him after you have obtained three gym badges. the marking map is a simple map of sinnoh and has several markers for intriguing places. it also marks the spot of the two roaming pokemon in diamond and pearl, mesprit and cresselia.
After you fill the sinnoh pokedex, go to Prof. Rowan's lab. Talk to him and he will give it to you.
You can find a fire stone at Fuego Ironworks, Stark Mountain (With Dowsing Machine).
The dowsing machine is on the pokewalker.
The two in pearl are Cresselia and Mesprit.
You can obtain potions and other helpful items for you and your Pokemon. You'll also need to use the dowsing machine in Pokemon Diamond, Pearl, and Platinum to find this lady's Suite key because she lost from watching the scenery around her.
NO THERE is no second map in diamond and pearl.(that includes platnium).