It sure BETTER be active in reverse! I've never heard of a 4WD vehicle that wasn't. As Justin says, you gotta be able to back out of whatever you drove into... I see Alceujjr's point; AFAIK, 4 "low" is created by the combination of the automatic's 1st gear and the lower differential gear ratios (I assume the TH normally starts in 2nd and only has 8 useable gears in normal driving?). However, that lower differential gearing is there all the time, whether in forward or reverse gears, so reverse should be a lower gear at all times, right?
Gear Ratios ZF 9HP 1- 4.713 2- 2.842 3- 1.909 4- 1.382 5- 1.000 6- 0.808 7- 0.699 8- 0.58 9- 0.48 R- 3.80 1 gear dont same reverse. Its very strong and short ratios gear but dont like the 1low. Reverse, reverse 4wd and reverse 4wd low = same ratios