4hi blinking/wont engage

First time post! I have searched and read through some threads on here and cant find exactly the symptoms my tundra is having. Here is the run down.

A few days ago, I attempted to engage the 4hi while out joyriding and the 4hi light was just flashing. I attempted it while stopped in park, reverse, neutral, drive; in each gear stopped and slowly moving. Nothing! I can hear a faint click as if the actuator is engaging but it doesnt fully engage.

I discovered today that while the switch is in 4hi position and blinking, if I turn off engine and restart, it will quit blinking and in fact be fully engaged! From there it will engage into 4lo as it should, back to 4hi as it should, and to 2wd as it should. HOWEVER, it will not go back to 4hi unless i stop it, put in park and restart the engine.

2014 Tundra with 160k miles and this is the first real issue that I have had and I am dumbfounded. Any tips, ideas, suggestions would be greatly appreaciated! I do not want to make a trip to the dealer for this issue. I can fix it, just need to know how to troubleshoot it correctly to change the correct part! Thanks!

 

Are you the original owner? If not, do you know the maintenance history? Dealerships are infamously known to replace the original 75W transfer case fluid with

$39 75W-90 GL-5 Limited Slip, Ultra Long Drain 500k Miles, Manual Transmission, Gear/Differential Lubricant (1 Gallon)

75W-90 differential gear oil because the OEM fluid is to expensive to stock on the shelf. There are lots of threads about it. Try swapping out the fluid first, purchase on Amazon.com, either $65 per quart Toyota 75W LF Transfer Case Fluid or $20 Ravenol per liter (it's German). Need two of either. There are Blackstone lab reports posted as well. I personally purchased the Ravenol. Good luck!

 

This all day!!

 

FYI. 4 hi should only be engaged while in drive and moving. It seems to work best that way. Also that’s how the manual says to do it. I like to do it at pretty much any speed under 60 and then just lift my foot a little bit. It goes right in. 4 lo has to be in neutral after it’s already been engaged in 4 hi.

 

Yes I am the original owner, bought it new. I know that it should be moving to engage into 4hi. However, for some reason it will not unless I stop, and restart engine. But it will shift correctly after that. The issue is going from 2wd to 4hi.

 

I will do that the first chance I get. I did see some of the threads on the fluid change, however it seemed the symptoms they were having was it would engage but would not disengage 4wd as if it was stuck in 4wd.

Growing on Amazon, found several different options for the transfer case fluid. Is this the correct one?

Ravenol J1C1003 SAE 75W Manual Transmission Fluid - MTF-3 Full Synthetic (1 Liter)

 

Yep. That’s the Ravenol I used.

 

You don't absolutely have to be moving to engage 4HI. It won't always go in right away, sometimes it will, sometimes it won't, but there's nothing wrong with engaging while stopped.

 

You really don't need to have worn anything in to get it to engage at a stop. It'll engage from a stop when brand new. It's not a matter of break-in or amount of use.

 

Yes it has been a couple months, I would say the last time I engaged it was July/August for a short period of time, backing in a boat to the lake. I never liked being on the ramp fully submersed in the back without 4wd engaged.

 

I did have the tranny services at 120k miles, I called the shop and verified it last night that they did not changed the t-case fluid. I also noticed today that it would flash longer than it normally would while moving if going from 4hi back to 2wd. I actually had to restart to get it to stop flashing. I keep trying it while out driving hoping it will eventually engage and start working properly.

 

When my truck was brand new I was backing up in 2wd and got to a point where I wouldn’t go any further. (I was off road). Tried to switch it into 4hi and it just flashed. Ended up having to pull forward in 2wd before it would engage.

from that point on I always try to have it in 4 before I need it, not waiting until I need it.

 

Yea when it was working, I had to sometimes shift from drive to neutral or reverse and it would engage. But now I can’t get it to do that unless I restart engine while it’s blinking.

 

I don’t know if this is the best solution but I would probably start by changing the fluids in the front differential and transfer case. Also with the help of a friend maybe get underneath there and see if you can tap on the actuator and get it to engage.

Also thinking outside the box here, are all your tires the same size and wearing evenly? I would think I missed matched tire could cause it not to want to line up.

 

I will definitely be changing the fluid soon. With the tires, they are the same size; HOWEVER, I had one replaced because of a defect and there is definitely more wear on one side than the other. I was basically trying wear the other 3 tires a little more before I put a new set on. You just may be on to something...

 

Why don’t you start simple. Have you tried to engage when you have traction? Does it work then? If either of the front wheels don’t have traction it will never engage. The light will just flash at you till it senses you have traction then engage. If you try that and it doesn’t work then try fluid, or whatever.

 

Yes, when I found the issue originally, I still had traction, attempted to engage before I start spinning in the mud. Thankfully I didn’t spin and get stuck.

 

Mine continues to flash from 4HI to 2WD as well.
I found that moving the knob from 4HI to 2WD and then slightly accelerating resolves this issue...Everytime.

 

i dont know if this would work for the tundra, but on my tacoma, i would have to slowly roll forward and slightly turn the steering wheel left and right for 4hi to engage. worth a try.

 

Maybe put that newer tire on the back and see if anything changes.

 

Mine flashes when I go from 2wd to 4hi. Usually no issues from 4hi to 2wd.

 

Tried that too, still no worky.

 

Ok, so also figured out today that if I get it into 4hi (after restarting motor) and drive it in 4hi for about 10miles or so, attempting to go back to 2wd, from slow roll, in neutral, park, reverse, the 4hi will continuously blink until I restart the truck...

 

When I bought my truck, I had the fluids drained and swapped...including the transfer-case...prior to the fluid drain and swap in the transfer case, Toyota fluids were in there...my 4WD activation and deactivation functioned as expected, smooth and right...since the fluid swap, I had 75-90 swapped in and I now have the same blinking 4WD light blinking on my dash longer then it ever should...it functions, but not right away...I was curious what was going on until this thread posted...I now believe the cause of this is due to the new fluid that was replaced in my transfer-case...I will swap to the Toyota or other equal brand to see if this blinking light is remedied.

 

Just wanted to give an update to my 4wd issue. There is good reason to leave skid plate installed...when I changed my motor oil Monday I noticed the front actuator was cracked. I currently have the part removed, working to repair the crack, since the actuator works, just not as it should. Doing this before shelling out almost 300 for a new, to see if it will work! Once it’s repair and ops checked, I will give another update!

 

Please take a pic of the repair as well. I am interested in seeing how it turns out. Good luck!

 

Update!

After 3 days of waiting, I got the front actuator back on the tundra, and the repair was successful! Here was the step by step process I did to fix it.

Day 1
- removed the actuator
- cleaned it up well with brake cleaner around the crack
- scuffed up the plastic along the crack with some 180 sandpaper
- cleaned it again, blew it off well with air hose
- using JB Weld with steel reenforcement, applied liberally all around the cracks
- clamped the around the crack to ensure it was as closed up as possible without putting too much force
- I let the weld cure for 24hrs

Day 2
- cleaned both actuator and differential well to remove old silicone and oil to reinstall
- used silicone specifically for gearbox to reinstall actuator
- let cure for 24hrs

Day 3
- refilled lost gear oil
- operational check of 4wd complete!

 

JB Weld to the rescue!
I once fixed a *rubber through A/C high pressure line with it.

Edit.: *rubbed, not rubber

 

JB weld has rescued several things for me! Just have to be patient and get the right stuff! Of course this issue would have never been an issue if someone would have left the skid plate on! I left it off because I rarely take the truck off-roading, I out a lot of highway miles on it. Leaving the plate off makes it much easier and faster to change oil! Needless to say, it’s going back on where it should be!

 

I found out my 2018 will not let 4Hi engage if Tow Haul mode is on. Works flawlessly otherwise.