I have had the same problem with mine.
it just starts blinking and never stop, one thing i noticed that I can engage 4H very easly.
Anyways I got under the car and checked, everything was in order.
so I got up to the to valves near the air box and hooked up the hose that comes from the canstir which has vac all the time and linked it to each one of them and tested the car until I found out that when you put it to the one comming from the blue spoted valve it stops blinking. But at this situation you can't engage 4H cause the front shaft is always dissengaged.

So the fix is to replace the valves

hope this helps, and of cours I wouln't be able to figure this out without that great HongKonger site