Milbrio9, The humvee has a mechanical Detent Control cable assy that works off of a rod that is attached to the Throttle braket. It is mechanical and is adjusted by loosening the lock nut and threading it forward or rearwards to reach the desired result. This adjustment is done at the left rear of the engine valley area. I don't think that a miss adjusted Detent would cause "slipping" in forward and reverse though. The switch that is on the right side of the Injector Pump and is actuated by the "Pack Man" looking cam is actually a switch that will open a normally closed circuit to that little electrical box that controls the Fan Clutch solenoid and probably the PCB as well. When the throttle is depressed enough, the circuit is opened and the fan is turned off for a period of time. This is supposedly so the fan can be stopped for water fording even though the vehicle may not have a fording system attached. I guess they had a problem with broken fan blades wheb people were driving into lakes and rivers and had to add this little complexity to the vehicle, Still it should not have anything to do with the Trans problem. The ambulances did have Reverse Lights, but they did not use the switch in the transmission like a GM car would, they had a switch in the shifter assy do the job of powering up the rear back up lights. The Humvee in question could be altered from original condition though. Not trying to be a smartie, just trying not to let someone chase wild geese around.