Is there a wise way to debug a large code?

[mpgmike]

Not that this would fix your issue, but you have:

DIMMER: 'auto dim routine
IF Z2=06 THEN HPWM 2,150,2000
IF Z2=08 THEN HPWM 2,200,2000
IF Z2=10 THEN HPWM 2,255,2000

In this case I would have used:

Dimmer:
IF Z2 = 06 THEN
 HPWM 2,150,2000
ELSEIF Z2 = 08 THEN...

What happens if Z2 = 07? Maybe use:

IF Z2 <= 06 THEN
 HPWM 2,150,2000
ELSEIF Z2 <= 08 THEN...