help please GQ auto trans problem

heres a strange one, i have a short wb GQ patrol which blows the transmission fuse only when in low ratio 4wd heavy accelerator going up a fairly steep clay & rock hill . hill is approximatly 45 degrees & 500 meters long i only get about 2/3 the way up & bang goes the fuse. on any other hill no problems low & high range & 2 wd all good, trans serviced (all good clean inside). anyone else ever had this problem im a mechanic & have the full WS manual but after 2 months am pulling out my hair ( there is not much left) thanks to any ideas
Craig

Sounds like a short some where I would start wiggling wires and plugs even the fuse box plus relays could be in the loom that goes down to the gbox might have rubbed and when you going up hill gives right angle for wire or loose connection to short out to earth.

Did you figure it out?