I wrote a Code for Control LED Lamps for model Car (via Bluetooth) . When I am powered up the HC-05 module through Arduino Uno board , All works perfectly.
But later I decided to save my Uno module's working power . So I gave external regulated 5V to HC-05 module . "+5V to VCC" and " - to GND" .
But when I powered up the circuit , Arduino board is not responding to the Bluetooth module (All indicator lamps on BT module and Uno are working). (Phone also connected to the BT module)
Then I reverse the process and set my circuit to previous working mode (Uno is powering up the BT module) . And its starting to work perfectly.