Auto loans liens and responsibilty?

The lien has nothing to do with your obligation to repay the loan, but only secured the loan.  The pawn broker has lost its security for your loan, but you still owe it the money.  Presumably, the loan contract provided that yiour sale of the vehicle constituted a breach of the contract, and accelerated the due date for payment (i.e. the entire loan became immediately due and payable.)  The pawn broker will likely now sue you for the amount owing.  It is possible that you will be able to negotiate a settlement of the debt, but otherwise the pawn broker is likely to obtain a judgment against you and begin collection proceedings.