4 wheel drive light won't come on.

Have a 2007 auto trans 4x4 which the 4 wheel drive dash light will not come on. I know all the manual suggested steps to activating it and it still won't come on. Only way it comes on is if I switch it to 4Hi and cut the vehicle off and then back on and then it will cut on. Once its on like this there is no problem of it actually engaging into 4 wheel drive. If I cut it from 4HI while its on back to 2HI it will switch, but cannot switch it back to 4Hi again without cutting the vehicle off and on again. I'm not getting a flashing light, the light isn't even coming on at all. I wondered if it was just the dash light not coming on and the 4 wheel drive still working, but that isn't the case. The 4 wheel drive is also not working. I've searched the forum for answers and found somewhat similar issues, but none of the exact same scenario. Seems most have issues with the light flashing, not like mine where it doesn't come on at all. If anyone could help me or experienced the same issues I could sure use some advise please.

 

jack up the vehicle, engage the 4wd and see what components are spinning, it's probably your t-case actuator as those are known to be total junk

 

I'll try that, and I've read that those actuators aren't worth a crap. I'm just wondering before I go that whole route, could it also possibly be a fuse that's bad?

 

There is a 20 amp 4wd fuse you can check, the possibility is remote but it would be an easy fix

 

If the fuse were bad the 4wd would not engage AT ALL. The OP says it will engage if he cuts off the truck and restarts it, so it wouldn't be the fuse. Just an observation.

 

So get this, I went and sprayed some the dirt off that was on it from the day the 4 wheel drive started acting up at a carwash, and sprayed good up under the truck and all of a sudden now its working fine switching it from 2Hi to 4Hi without having to cut the vehicle off and on again. Personally I think its the actuator about to go completely bad, and maybe a piece of mud got caught up on it and made it quit working all together. I don't think I'm in the clear now just because it started working again, its only a matter of time before it goes back to not working. You think its the actuator itself or a wire or something running to it?

 

Hey, im experiencing the same problem now. Did it ever start acting up again or did it keep working right?

 

I have an identical problem with my 2007 tacoma,did u find the problem

 

I know this is an old thread but i am having this issue. I see a lot of other people are too but i have yet to see any resolutions?

 

I have a 2005 tacoma with the exact same problem. The light will not come on when switched to 4WD and it will not engage the 4WD either. The problem is intermittent. Also like above if the start the vehicle with the switch in 4WD the green blinking light comes on and it will engage the 4WD. I see that on the post for JAN 20 2015 that someone sprayed the actuator and it started to work. Can someone tell me exactly where the actuator is so I can try it. Also I have trouble shot the ECU and when it does not work pin 22 on connector B stays at 12v and when working it goes to 0 v. This suggests that the transfer indicator sw T2 is not closing. Can anyone also tell me where this is located. Appreciate any help.

 

The transfer case switches are on the back of the transfer case, they are inside the actuator and are a bent prong type limit switch that rides around the back of the actuator case and makes contact or open circuit positions to provide to the 4wd ECU depending on the motor position. The only way to inspect is to remove the actuator from the truck, it looks like a big black hunk of junk hanging off the back of the transfer case, held on with 3 bolts.

 

Check the brake fluid in the reservoir. Too low and it plays tricks on going into 4wd. I had it where it would go in and then not. I also did the brakes around the same time. When the reservoir filled back up, it's worked without issue.

 

Thanks for the help locating the transfer case switches and for the tip on the brake fluid. I checked the brake fluid and it is fine. The the 4 wheel drive transfer switch T2 going to pin 22 on connector B does work because when it does go into 4WD mode the voltage goes from +12 to 0 Volts. When it does not work it stays at 12 V. Not sure the proper sequence of events. Maybe the voltage is only suppose to drop when the 4WD is engaged. In that case it is working properly. When the green blinking light does not come on I do not have 12 V going to ECU connector B pins 3 and 4 which sort of tells me that there is no voltage going to the actuator motor. Pin 15 of connector A always goes from 0 to .700 V when the 4WD is selected on the dash. What I am missing is what triggers the voltage to the actuator motor. Also the 4WD always engages if the truck is turned off and started with the dash switch set to the 4WD position. Any more help would be greatly appreciated.
Also looks like from previous threads that several people have had the exact same problem yet no one has posted a solution. If anyone has solved this problem please help.

 

Hopefully this will help. From what I can tell, your transfer case is shifting into 4wd. And let me correct my previous statement, I thought you were talking about the limit switches, the T2 switch is a switch that looks like a reverse light switch in the transmission, it's a gray plug that is threaded on top of the transfer case actuator (black thing on the back of the t-case). I've attached a file that hopefully will lead you to the right solution, sounds to me like your ADD actuator is going out. I had similar thing happen to me. I would take the voltage readings as described in the attached document for further info, then remove the ADD cover on the front diff and inspect that.


The sequence of events is as follows:

The ECU receives input from sensors the 4WD and L4 position switches that monitor transfer case shift shaft position to determine engagement.
The ECU then engages the ADD actuator to lock the front differential.

 

My issue. After I removed the ACC cover and cleaned it I noticed a worn out area trail on the outmost metal. Then trimmed the rotting end of the rubber hose ,put it all back together.and went out for a test run...it went into 4hi after a few tries, then...when put in to 4lo it went to shit! I got no drive in forward or reverse and was making a terrible grinding noise. So after many attempts switching to off then turning the key off and on,not sure exactly when but the fwd light went out and resumed 2wheel drive. Whew ! Missed the tow truck bullet! Now what? My initial problem is blinking 4hi lite.

 

This part should be a recall. T-Case 4wd Actuator.
I miss my 82 SR5 and locking my own hubs.

 

Sounds like it wasn't engaging. What is the deal? Anyone know were to get it fixed? Any place but the Toyota dealer.

 

Where do you go for this repair?

 

Your driveway. Unfortunately nobody has much knowledge on how the system really works

 

I'm hoping to fix it by replacing the actuator. But they are very expensive. Anyone got one or know where to get it cheap?