I know this is digging this tread up, but i have this problem with my navara.
I have tried changing the neutral selector switch and it didn't solve the issue, I have even unplugged it and manually opened and closed the switch when driving. 3rd and 4th are still not pulling. I cant actually figure out what this switch does. As it drove no differently weather the switch was closed or open.
Of the 2 switches on the gearbox, One is the neutral selector switch, the other is the reverse light switch. Surely this problem can't be mechanical..
Any help will be much appreciated.
Thanks
Ben
May 2009