The 4 wd on my '01 4Runner won't engage. I tried "hitting" the a.d.d. actuator w/ a hammer to see if that would free it up and unplugged the 4wd ECU, neither worked. Any suggestions??

If it is electronic activated 4 WD, this system has a transfer case control module located in the dash behind the climate controls.It can go bad and cause the system not to engage the 4WD. May want to check power and ground to the module first.

In the transfer case is motor make sure that is working

People with 4wd vehicles do not follow the advice of the owners manual,every 3 months they have to activate the 4wd system or the actuators are going to get stuck when you really need them. solution, you will need an assistant if the car is in the air even better, if you trust you mechanic ask him to do this for you. with a rubber hammer hit(tap) the actuator the one in the front differential and the one in the transfer case 75% of the time this trick work, if you need pictures tomorrow when I am at work I email you a couple.


Flavio P

Master Diagnostic Technician for toyota.

If you need further help, I’m available over the phone at https://www.6ya.com/expert/flavio_517b938f50183b92

physically watch the actuator and have someone else activiate it. If it moves like it's supposed to...you could have a broke axle, third member or even the locking clips on one of the front hubs...

The modulator at the transfer case probably stuck and may need service or replacement. Use a rubber mallet and hit actuator where it bolts to case careful don't hit the connector. If it moves than remove and lube the actuator shaft. If it don't move, than remove and check shaft for bent or damage. Try to shift to four high. If actuator activates and shaft does not move most likely replace, but have part checked by auto store first.

Spray some wd-40 and get a bigger hammer, hit it hard you won't damage it.Just be careful not to hit the stud's.

hit it from behind with a heavy hammer it's probably rusted on

The vacuum switch on the transfercase is most likely the problem. If you remove it and the plunger is stuck in, replace it and your 4wd should engage again.

Before changing the actuator check the vacuum lines at the vacuum switch on the left side of the transer case if they are wet with transmission fluid the the switch is bad and that will prevent 4wd from engaging.

I have a 1994 ford f150, my 4 wheel drive keeps trying to engage by itself even without me touching the automatic hub button....at time you can even hear it engaging and disengaging by itself, the low range light even comes on (dimly)...what could be the cause? the transfer case motor looks good and so does the wiring.