[grid@testdb1 ~]$ sqlplus / as sysasm
SQL*Plus: Release 11.2.0.3.0 Production on Mon Apr 3 16:34:25 2017
Copyright (c) 1982, 2011, Oracle. All rights reserved.
Connected to an idle instance.
SQL> startup
ORA-00099: warning: no parameter file specified for ASM instance
ORA-15149: another ASM instance found running on the host
[grid@testdb1 ~]$ export ORACLE_HOME=/opt/grid/product/11.2.0.3/
[grid@testdb1 ~]$ export PATH=/opt/grid/product/11.2.0.3/bin/
[grid@testdb1 ~]$ export ORACLE_SID=+ASM
SQL> select instance_name from v$instance;
INSTANCE_NAME
----------------
+ASM