You start by removing all lower dash trim. Then watch to see what moves or doesn't move when the MODE is changed. Then see if some things (aka door actuators) that don't move, will move with a little push.
The door actuators are usually two-way vacuum diaphragms with rods to the door levers. It should be obvious if one looks like it's trying to move but won't. Another, step is unhooking the rods from the door leverss and seeing how the actuators move then..
I have a Blazer that would not work properly with out removing one of the return springs on a door. Door moves freely by hand, actuator moves fine when not hooked up, but, won't work when assembled with spring in place. GW
DLW wrote: