4WD Diagnosis

No cigar. I’ll see if I can trick the ECU. But I’m noticing a grinding I didn’t notice before when I’m in drive so maybe I screwed something up.

 

When you install the actuator, you have to take care about the position of the shift rod. With out the actuator installed, you can move the rod in/out through 3 positions - neutral, 4HI, 4LOW. Be sure that the rod is in the neutral position. Similarly the actuator moves through those positions by spinning the geared wheel inside, and thus the tiny gear that moves shift rod. I forget which way is which, but you'll have to figure out whether the neutral position on the actuator is full clockwise or counter clockwise. With the rod in position and the actuator correctly oriented, go ahead and mount the actuator and drop the little gear in place. If everything else is copacetic then it should cycle through the positions as intended.

You may have noticed a dimple on the shift rod. When it is in the right place it engages one of the two contact switches, which inform the ECU about the position of the rod. If you're off by even one tooth it won't work (I know this first hand). These switches closed without the rod installed, so you can check their function with a meter before install.



You're using the new junkyard part, right. Did you open it to check inside?

 

Did you need to have all 4 wheels off the ground so you could relieve any tension when manually moving the TC shift rod?
(Like so you could grab the front or rear drive shaft and free up the tension)
When I tried to move it manually I could not budge it, in or out by hand with all 4 wheels on the ground.
Currently mine will go into 4H only, flash when trying to go into 4L.
I worked on this a little over a year ago and am still curious what I was missing or what the issue was.
Note: To anyone who removes the little motor's housing... there is a tiny ball bearing at the end that's free to go rouge when you open it.
I found this helpful photo as well back then.

 

I did. It was pristine inside. I’m actually only using the cap, not the whole actuator. I may have placed the contacts in the wrong position so it’s confused. It rattles while I’m in drive, disengaged or not. I’ll have to pop it back off to see if I can do what y’all mentioned. Can I take the whole actuator off and just shift the shaft with the actuator off and once it’s in the neutral position, place the actuator back on? Thank you. Merry Christmas haha

 

BroHon, I have the same situation going on with my Tundra. I can go in and out of 4Hi with no problem. If I am in 4Hi and put the transmission in neutral and then press the 4Lo button, both the green and amber lights start flashing. I tried many times to get 4Lo working but no luck. If you ever figure this out, please post the solution. I'll promise to do the same if I come up with the answer. Merry Christmas!

 

May not be a fix all, but that’s how my problem started. You could pop your cap off and check the contacts. Mine eventually progressed to no 4wd period.

 

BobbyRaid, I remove the TC actuator by removing the 3 electric connectors and the vent tube and then the 3 bolts that attach it to the TC. I then remove the 3 screws that hold the gear plate cover. I pull the gear off with a needle nose.
The entire actuator will come off but the shift rod will remain attached to the TC.
Then, I also remove the 3 screws from the actuator cover and rotate the gear fully until is stops (either CW or CCW, I forget which way) so that shaft the small gear attaches to is moving in the direction that would move the shift rod into the TC if it were attached.
Next I manually push the shift rod into the transfer case as far as it would go (so it is sticking out about of the TC by 2-3/4").
Since the gear inside the actuator is rotated in the correct direction for the TC to be in the neutral (2WD) position and the shift rod is also in the 2WD position, you can install the 3 actuator cover screws (but make sure the little gear shaft doesn't move. You can hold it with your finger to make sure it doesn't move while you reattach the actuator cover). Now you can slide the actuator body on to the TC shift rod and then slide the small gear back it place. The little gear should be meshing with the 1st tooth of the shift rod. Install the gear cover plate with the 3 small screws. Fasten the actuator down with the 3 bolts and reattached the 3 electric connectors and the vent tube and you should be all set. It all might sounds like a lot and complicated, but it's really easy and takes me about 15 minutes. There are a few Youtubes on how this is done. Good luck.

 

After seeing all this all, I’m wondering if we shouldn’t be recommending people to remove their cap, grease the contacts, and replace the vent tube as part of “regular maintenance”. Is there any concern with removing the cap in general, any “aha!” Or “gotcha!” To worry about during removal or reinstall?

 

I'm too scared to open mine up. haha

It definitely probably needs a clean up and maybe it'll explain why my 4wd HI tends to bind and release with a minor bang when releasing after driving on dry pavement for short distances in a forward/reverse straight line direction only.

Thankfully, it doesn't do that on loose gravel/dirt or snow/ice covered roads.

 

Mine does the same actually, if I disengage while coasting, clunk/bang. The only way to get it to not clunk/bang during disengagement is to have it under load when tapping the button off.

 

I'm curious what has worn down to do that. Originally these trucks would shift in/out of 4wd HI seemlessly moving on dry pavement in a straight line and you would barely notice it.

 

I also don’t remember hearing that when I first got the truck, and I’ve seen others complain about it on different forums too. I presume it’s something in the front diff. But again, 4WD is not my forté, and I’m not shy about speaking that truth on here.

 

If it ain't broke don't fix it. I broke two of the three cover bolts, and had to drill and re-tap. I broke 1 of the 3 screws on the cover plate, same remedy. When I got inside it wasn't so bad, but it took me all day to figure out how to re-clock the gears (BroHon's pick above could have saved me hours of trial and error). My opinion is that as long as the breather tube (oft mistaken for a vacuum hose) is intact, it's not likely that the inside contacts are full of schmootz. And when you do take the actuator off it can be bench tested before opened. But of course you and a helper can test its function while it's still attached to the transfer case. My opinion, however, is only worth what you paid for it...

 

Sounds like your take is, it’s not worth exclusively popping the cap off (even for a rust-free truck) to clean and re-grease the contacts

 

Thank you all for the valuable information , for reassembly and the basic behavior. Mine too clunks a bit more than I'm comfortable with.
Christmas eve day, 46deg, I am so tempted to get out and fiddle with this again...
If I do it's getting put up on all 4 wheels and put in neutral, see if I can manually get her in 4LO.
EDIT: and continuity test those two switches.

 

Valuable details man, thanks!

 

Hey guys, I’ve been having issues today with my 4wd. I haven’t been using my truck much. Figured it would be a good time to engage 4hi and 4lo.

Please excuse me if I’m reading the previous posts incorrectly but, my 4lo engages and disengages fine from 4hi.

my problem is getting back into 2hi from 4hi. The 4hi blinks on the dash in tandem with the button. Button is disengaged also, but truck stays in 4hi. I think. Feels tight while turning as if in 4hi.

I tried everything but getting under the truck and looking at the vent line and contacts. Will do that in the morning.

I am way out of town with the family and driving 4 hours in 4hi sounds like trouble. Any suggestions to get me back in 2hi would be much appreciated.

Thanks a lot and happy holidays!

 

Simplest thing is to go forward and backward 5-10 ft on a dirt road so it can give if it’s binding. May just need a little exercise.

Beyond that you may want to isolate it to the front diff or transfer case by seeing if the front driveshaft is still turning or not.

 

Tried all day to get it fixed… ended up taking the cap off the actuator. The outside ring was completely corroded. Sanded it, put back together. No luck.

Ended up turning the main gear counter clockwise, pushing it all the way towards the diff. In that position the front diff is in Neutral. Boom no longer in 4hi. No codes on the ODB. Next trip after getting home will be the junkyard for a non corroded actuator cap.

 

Meanwhile, confirm you can shift into 4lo while in 4hi and neutral. A few others on here have found they couldn’t after similar, I’m curious if you find the same.

 

Can confirm shifting into 4hi and 4lo. It will not go back into 2wd from there though. It was just a fix to get home. The N contact was completely corroded to the plastic.