One of the first MOT problems was poor braking efficiency at the rear, I could not sort this one out. However a mention on the difflock site had Zukijimny mentioning bias valve.

The Jimny has a variable (automatically adjusts with load) bias valve location above the rear axle.

It is mounted to the body and attached by a spring to the axle.

Of course, for the MOT the car was emptied, including removing the spare wheel from the back door (because of concerns about obscuring the rear lights) meaning there was no weight (no seats, no tools, no carpets - nothing). With no weight in the back the bias valve is basically switching the rear brakes almost totally off. There is an adjustment on the valve but mine was almost fully adjusted already due to the spring lift. Therefore I loaded up the back with the spare wheel and tools - and passed!

Martin