2012 wont go into 4wd. researched and tried to repair myself, need advise!

my truck is a 2012 5.7 4x4. 108k miles, ive had it for a year. no issues with 4wd system until thanksgiving. I use 4wd regularly to go camping and dirt bike riding but i dont beat on the truck at all.

so thanksgiving, headed to glamis sand dunes, driving thru some snow in the mountains so I switch to 4wd hi. no issues. back into 2wd. no issues. keep driving and the desert is flooded. I cross quite a few 1-2ft water crossings. drive for another hour or so and 4hi, 4lo, are flashing. abs and tc are solid. I pull over and mess with the 4wd selector switch. it goes into 4hi and wont come out. Whatever im only 30 min away, its raining, and going to need 4wd when i get to the sand.

next morning I do some research with limited cell service and decided to pull the 4hi actuator motor on the transfer case. when i do all the gears get seperated and I have no idea how they go back. i take it on and off about 4 times and finally get it into a position I feel is correct. by the way everything looks perfect. no corrosion or rust like ive seen in other posts.

few days later I drive home and all the lights on the dash are off for a couple hours, but they turn on again when Im close to home, same lights.

Now I can finally do some real research. I start testing things. at this point all dash lights are off again. When i turn it to 4hi, 4hi flashes and the front drive shaft locks. I put my ear to the ADD motor on the front axle while my wife turns the switch from 2hi to 4hi. I hear nothing. I also checked wheel speed sensor wiring, abs wiring. I checked voltage at the plug to the ADD while the switch is set to 4hi and i have 12v at 3 or 4 of the pins.

Ok so I figure the ADD motor is bad. I order one from the dealer and get to work yesterday. Pull off the old one and its in the 2wd position. I turn the switch to 4hi with the old motor pulled, no movement. The new one from toyota is for some reason in the 4hi position. I plug it in without installing it into the axle and it immediately resets itself and moves the fork to the 2wd position.

Im thinking great this was the problem. I install the new ADD motor and let the rtv set up overnight. fill up the diff this morning and take it for a drive. when I shift to 4hi it just flashes and still will not go into 4x4. So now im really confused. Im thinking theres a chance I didnt get the fork positioned correctly over the collar in the axle so I pull the new ADD motor off. I plug it in and my wife switches from 2wd to 4hi and the fork does not move over.

What should I look at next? Like I said theres power at the ADD plug but im thinking a switch or sensor on the transfer case isnt telling the ADD motor to move. I believe the plug with 2 wires that goes into the 4hi actuator on the transfer case is the position sensor but I cant find much info on it

***** Sorry for the super long post but I wanted to get all the information out there!*****

 

It seems like you've been through most of the system, but a few things you may try:

1. Disconnect all your T-case connections & inspect the pins (water may have gotten inside) for corrosion etc. Blow them out & apply Ox-gard to all the pins, plug them in, remove, plug in again.

2. Do the same to the electrical connection on your front diff.

3. Pop the console panel off your dash & do the same to your 4x4 selector switch connection.

I had some weirdness going on with my 4x4 electric's several months ago....all lights on dash lit up, not shifting etc. I did this procedure (along with batt terminals, grounds & every plug I could find) & it's been solid since. As a marine mechanic, I can tell you that water (especially salt water) can do some very strange things to enclosed electrical connections. Might be worth an hour to go through it. Best of luck with repair hombre'

Edit: also...welcome to the forums

 

thanks for the reply.

I reinstalled the ADD motor yesterday and then decided to pull the 2hi-4hi actuator on the transfer case again. I held the actuator in my hand and had my wife switch to 4hi. Well for some reason the gears lift up just enough that the metal tap is not hitting the “4wd detection switch” the tab just barely goes right over the top of it. In the picture the red circle is the “tab” and the blue is the detection switch. If I hold the gears down with my finger the tab will hit the switch and lock the ADD motor. When I install the t case actuator motor the switch is not getting hit so the add motor won’t lock. I’m not sure why the gears are lifting up a bit? Any ideas?

 

Your deeper into that system than I've been...so the validity of my suggestion may be lacking. I wonder if the receiving side of that actuator (in the t-case) has a dowel pin for it to fit into? It looks like the center pin would fit into a small hole. If so, makes me think that would apply the pressure that you replicated with your finger? Is there a chunk of foreign material wedged under on of the gears, or a rusted spring (you said you pushed down on the gears...I'm assuming it was under tension?). My thoughts keep going back to the 2' water crossing as the culprit...but maybe coincidence.

Edit: also, is there any deflection in the gears/ rotating assembly of the actuator? If so, that may be causing it to rise up or bind.

Might be time to hit up a pick-n-pull/ junkyard for a test actuator.

 

Yes there’s a hole the pin fits into, I have no rust or anything weird going on in my housing if anything maybe a lack of grease?

the only thing that could put some tension on the gears are the 3 limit switches that contact the housing to tell the ecu what position the motor is in

 

The actuator motor housing with the gears removed (not my picture) you can see the circuits the limit switches drag across

 

Are you sure all speed sensors are good? Bad sensors prevent the truck going into 4wd.

 

Yes I’m sure, the tab not hitting the 4wd detection switch is my problem

 

Did you preload the actuator when you reinstalled? Remember that it's under spring tension and has to be put back that way. I used a 12v battery and some jumper wires at the connector to engage the motor slightly when putting it back on to get the spring tension right.

 

No I didn’t do that, I was actually just reading about this and going to try it tonight

which pins on the connector activate the motor?

which way does there need to be tension? Pulling the rod out (4hi) or keeping it towards the tcase (2wd) ?

 

The rod has to be all the way in to set it right. It's the first two pins toward the engine on the connector and if you have the polarity right it will twist the actuator clockwise. Don't over do it and try to remember what it felt like coming off. Because it's a simple motor depending on where you put the positive and negative will determine what direction it spins.

 

I tried to tension the actuator then install it and in the process the tiny 4wd detection switch fell off. I very carefully reinstalled it only to find it was broken. I know this because I used a wire to jump between the 2 posts.

So now it doesn’t matter that the tab doesn’t contact the detection switch because the switch no longer works!

at this point I’m thinking I will tap into the wire for the detection switch and install a aux switch in the cab

 

tag for outcome.

 

How much do you set the tension. And how hard is the rod to move that goes into the transfer case.

 

You can either twist the motor cover a little while installing it or apply 12v to the motor when you install it. The rod moves easy with the trans in neutral

 

Finished up today. Ended up wiring a aux switch in the cab to activate the add motor. On the plug that goes into the 4hi actuator motor on the transfer case it’s the yellow wire with a green stripe. When that wire is grounded it tells the add motor to slide over.

so now to activate 4wd i turn the selector knob then flip my aux switch and to go back into 2wd it’s just the opposite

 

Hey, could you post a picture of your aux switch setup? I'm having the same freaking problem. Spent all day taking apart the 4hi actuator motor.

 

I don’t have the truck anymore but I just got a aux switch off eBay that fit into one of the blanks to the right of the steering wheel

 

Did you sell the truck? I’m trying to imagine how your 4WD selector solution went over.

 

Yeah I sold it, what do you mean?

 

Was the wire you were talking about connected to the 4hi actuator? That little gray switch that is supposed to tell the ecu it's in 4 hi?