pmburesh,
Since your issue may different, I split this topic off from the other one.
How do you have your GPS connected? And which GPS do you have; GR16, GR50, or GRHA?
If you have it hooked into the Interlink and use a GR50 or GRHA, make sure you power on the 1197 first and let it lock on the GPS. The 786 does not have the power to handle the newer GPS GR50 and GRHA.
Also, make sure you have good batteries and a main bus that is large enough to handle all the loads on your electronics.
Let me know your setup specifically how you have everything wired and we can start troubleshooting.
Robert