Quote Originally Posted by Ioannis View Post
The weak pullup on GP3 is enabled only when MCLR is enabled.

You may try also ANSEL to set it to

DO
ANSEL=0
PAUSE 500
ANSEL.3=1
PAUSE 500
LOOP

This will enable and disable the weak pullup.

Ioannis
tried, not working. ANSEL.3 is for pin GP4 not for GP3.