Have you tried using the db2level command to find where it is installed, then see if your system is configured to use the db2jcc4.jar file, which is the type 4 driver.
https://www.ibm.com/support/knowledgecenter/en/SS6NHC/com.ibm.swg.im.dashdb.admin.cmd.doc/doc/r0009195.html
#Db2#Db2forLUW#Support#SupportMigration