If your yorkie is scratching alot at his ears and the stuff you're getting out is dark brown, it could be ear mites. If cleaning the ears don't work with the cleaner that Babbie was talking about, then you may have to go to the vet for mite medicine.
I know I've had dogs in the past the ear mites and they have had the really brown waxy stuff and scratch at their ears alot.
Hope this helps
Cyndie and Trevor