ADD front diff?

You need to get under the truck and reach up and turn the drive shafts by hand. Which shaft is free? If either side will not turn by hand then it is unlocked at the other side and the differential will idle. It's all still turning when the truck is rolling, wasting power by heating up the oil in the differential but since one side is unlocked by the ADD it does not transmit power.

Everything must still be turning or we can't lock up on the fly and must stop to shift in 4WD. Shift on the fly means all the parts are in motion and the ADD uses vacuum or a motor to lock a clutch on one side of the differential.

More trouble then they are worth. Better to have hubs and just keep them locked in the winter or before leaving the pavement and free on the dry summer roads.

 

I have an 01 tacoma V6 automatic and I hit the button to engage 4 wheel drive and I get 2 sometimes 3 wheel drive. I hit the button to go out of 4 wheel and my light flashes at me. After driving around for about a month annoyed trying to figure out what was wrong I got hands on. So on level ground truck in neutral and transfer case in neutral I removed the bolts from the actuator on the transfer case and popped it out of the gear it was stuck on. Well it got my truck back into 2 wheel drive, so I decided to try my 4x4 again, no solution same problem, so back in the driveway to pop the actuator out of gear again. I have been driving around like this now for several months. I am puzzled, a handfull of other 01-04 tacomas are having the front diff actuator go out on them. Could I have done any damage by popping the rear diff actuator out of gear? And if my problem is in the front actuator why would popping the actuator out on the t-case help?
I ultimately would like to put a manual t-case in, I noticed that was being discussed here as well. Looks like I've found the thread I've been looking for all these months. Hope I can get some answers. Thanks in advance!

 

What do you mean sometimes 2 and sometimes 3 (wheel drive)? Popping the rear diff. actuator?

Normal 4WD with open differentials, power (torque) goes to all 4 wheels, but the differential will transfer more to one of the two tires per axle unless the traction is totally equal under the tires. If you get stuck in 4WD, you may see just one tire in front and one tire in back spin... (is this what you mean by '2 wheel drive' when you are in 4WD?)

A differential locker (The Off Road Tacoma has this on the rear, locked with an electric motor on the differential, and activated with a button on the dash marked 'RR Diff Lock' in low range). It causes both rear tires to turn equally even if one is in the air or on looser terrain than the other...(Is this what you call 3 wheel drive?)

The rear locker light is not the same as a 4WD light, and will flash at you if the button is pushed while you are in H2 or H4, but will only go solid (and engage) when you are in L4.

 

I have never messed with the rear locker/never had to. Sounds weird I know. My 4x4 worked great for the longest time, then started to slowly give me issues wanting to come out of 4x4. I would push the 2-4 selector button and could hear it trying to get into 2 wheel now I don't hear anything happening to try to get into 2 wheel. Driving around town I noticed that it would pull really hard to the right at times esp excelerating and my turning radius was shot as if I was in 4x4. I started searching around on line for an answer reading thread after thread. I honestly can't remember what made me pull the bolts from the actuator on the t-case, when I did though I could only pull it about 1/4 in, being the cowardly lion at this point gave a tug nothing had a thought and choked the front and rear tires put the tranny and t-case in neutral crawled back under gave another tug and it released.. really not the right word but close enough. It was as if it was engaged I'm not sure. I'm really still learning a lot about this 4 wheel sytems. I threw the bolts back on fired her up back out the drive and as soon as I did I could tell I was back in 2 wheel drive again. So to test it I tried my 2-4 selector button again and it tried to go into 4 wheel but put me back into that what feels like 3 wheel drive scenario. So I pulled her in and repeated process and have been driving in 2 wheel since. I'm pretty sure both back tires were spinning when I was stuck in 4 wheel, the front right wouldn't always stay engaged I could be driving and it would be fine one block and the next block start pulling again. Trying to be as descriptive as possible without rambling and repeating.