GRMG data collector method is started by the AutoAbap dispatcher program SAPMSSY8 and that it should be started by a GRMG background job in the transaction SM37.
In the transaction SM37 can be seen which GRMG background job is started every 5 minutes for this (note 1160083).
"If in the GRMG-Lite scenario a user and encrypted password is defined, please try to start the GRMG scenario in client 000, to see if the encrypted password can be found in client 000. If it cannot be found in client 000, you have to recreate the password again in client 000, as described in note 1323253."
908760 - NetWeaver - GRMG Portal Heartbeat
1134713 - STRING_LENGTH_TOO_LARGE in GRMG_APP ABAP-Service
974742 - ABAP Service GRMG_APP: MESSALERT in Response reset
1175659 - CCMS:Availabilty Monitoring for Loyalty System.
Please check how the GRMG data collector method is started in the <SID> system. If this is done by a background job, as described in note
1160083, than please check if the related background job is correctly scheduled in the transaction SM37 If the GRMG data collector method is not started by a background job, please open the complete GRMG monitoring structure in the transaction RZ20 and please select from the menu on top of the RZ20 screen "Views> Status data collector" and please inform us about what is exactly reported behind each GRMG monitoring node
GRMG Monitoring of SAP NetWeaver Components:
http://help.sap.com/saphelp_nw70/helpdata/EN/de/9bdb4064da712ae10000000a155106/frameset.htm
Configuring GRMG Monitoring
http://help.sap.com/saphelp_nw73ehp1/helpdata/en/49/1758d6a2e314cde10000000a42189b/frameset.htm
Activating and Customizing Monitoring with the GRMG
http://help.sap.com/saphelp_nw73/helpdata/en/34/60cdd0d3fdeb4cb8cbc4eac681f961/content.htm
Monitoring the Availability of Web Pages with GRMG Lite
http://help.sap.com/saphelp_nw70/helpdata/en/6d/6fe040852f712ae10000000a155106/frameset.htm
Trouble-Shooting GRMG Scenario Execution
http://help.sap.com/saphelp_nw70ehp1/helpdata/en/49/35125876aa5817e10000000a42189c/content.htm