The steps for configuring the APPS Tier to the new Database Tier

1.Bring down the Application Services
cd [COMMON_TOP]/admin/scripts/[CONTEXT_NAME]
adstpall.sh apps/[APPSpwd]
2. Modify the below parameters according to the New Database Tier
  s_dbhost
  s_dbdomain
  s_dbport
2. After modifying the above values run autoconfig on the APPS Tier.
cd $AD_TOP/bin
perl adconfig.pl contextfile='absolute path/*.xml'
or
cd [COMMON_TOP]/admin/scripts/[CONTEXT_NAME]
adautocfg.sh
3. Start the Application Services
adstrtal.sh apps/[APPSpwd]

Known Issues :
Sometimes the CM wont start as it will be pointing to the older nodes so we need to change it manually in Oracle
Applications Dashboard and restart all the Managers.