I bought a "new" controller to use with my 8-month-old Phantom 2 Vision + and everything worked fine for a while. Now, however, when I turn the controller on the rear LEDs continuously flash GREEN-RED-RED-RED (the REDs are very quick flashes). The rear LEDs no longer blink yellow or green depending on GPS.  Can anyone suggest what the problem might be?

"the rear LEDs continuously flash GREEN-RED-RED-RED (the REDs are very quick flashes)"

This is normal if you are in NAZA Mode and you have less than 5 satellites locked. Have you just switched to NAZA Mode via PT2 Assistant? Cheers.

Godfrey Posted at 2015-6-2 07:20
"the rear LEDs continuously flash GREEN-RED-RED-RED (the REDs are very quick flashes)"

This is no ...

Yes, I switched to NAZA mode as you suspected. Once I get 6 satellites, all is good - I get the blinking green light. *** THANK YOU for that information! ***

One more question: After I get 6 satellites I notice that occasionally the rear LEDs blink GREEN-RED repeatedly, and then go back to GREEN. What does that mean?

rob.elliott82@g Posted at 2015-6-4 01:44
Yes, I switched to NAZA mode as you suspected. Once I get 6 satellites, all is good - I get the bl ...

You need more than 6 satellites to have a slow all-green rear led flash. That means 7 or more satellites. Again, its normal in NAZA mode. Just be careful, if you are seeing the occasional red during flight, you could start drifting (ATTI Mode) and will need to provide constant control inputs to the bird. Do you take off from an open field or tree/building surrounded area?

Godfrey Posted at 2015-6-4 07:45
You need more than 6 satellites to have a slow all-green rear led flash. That means 7 or more sate ...

I was in a field at least 100 feet from the nearest tree. Does NAZA-M mode require more satellites than Phantom mode in order to be in GPS flight?  Thanks.

Nope, 7 is still more than 6, the Naza LED's are correct.
Personally I have never flown with less than 9, flying with 6 or 7 means that you only need to lose 1 sat and you are in ATTI mode, which is fine if you are expecting it.
I would wait for the 2nd set of rapid green flashes for home point set before take-off.

rob.elliott82@g Posted at 2015-6-5 03:14
I was in a field at least 100 feet from the nearest tree. Does NAZA-M mode require more satellites ...

I use an app to let me spot the approximate location of sats. Sometimes, they are low, near the horizon so I need to fly higher to achieve LOS on them then while hovering, I ensure Home lock by flipping S2 at least 5 times.
Follow John's advice, try to get at least 7 sats while on the ground, ensure you have Home locked-in and its correct (not 500 meters away), before take off. Cheers.