Stuck 4Hi

Hey there, first time long time.

a few weeks back I was driving around some mountain roads and eventually got to some snow. Tried to put my taco into 4lo to gain some traction but it didn’t want to lock in. Got turned around, switched the dial back to 2wd and drove home with no problem. Next day I went out and my truck was in 4hi. I swapped out the actuator on the front differential and it went back into 2wd. A week later while driving home a noise came out of no where (thought a belt got thrown with how it sounded) got home and as soon as I hit the driveway back into 4hi it went. Replaced the selector switch on the dash and nothing. Figured someone here has run into a similar problem and could point me in the right direction? Before going to the shop and paying an arm and a leg. Thanks!

 

If you really want to fix it.
I’d start here.
https://www.tacomaworld.com/threads/4wd-system-operation-help-thread.742420/#post-26430333

 

Your saying it's in high with the switch in 2wd as in the 4wd light is on solid or is the 4wd light flashing but you can tell it's locked in?

 

You might look at the harness to the actuator.

 

@Dm93 the switch is in 2wd with the 4wd light flashing and I can back up or go forward and once I turn my front tires grab like they are locked in

 

That's interesting I've never heard of a Tacoma shifitng into 4wd by itself, it's very common for people to get the flashing 4wd light and not be able to change modes but this is the first time I've heard of one shifting on it's own while driving.
I think the first step would be to check the vent hose going to the 4wd actuator on the transfer case, if it's cracked or disconnected odds are water and/or dirt got in there and messed up the limit switches (it can be taken apart and cleaned if it's not too far gone)
https://www.tacomaworld.com/threads/stuck-in-h4.731962/

If that looks ok test the limit switch voltages at the 4wd ECU as outlined in the thread @TnShooter linked above and post the results and we can try to decipher which circuit we need to go after.

 

@Dm93 I got under and looked at the actuator at the t case and the little hose coming off and running up was cracked and wore out. I’ll have to pull it out when I’ve got more daylight and break into it

 

@TnShooter @Dm93 didn’t feel like wait so I crawled under and popped the cover off. Water inside. Still worth testing the limit switch voltages at the ECU?

 

@TnShooter @Dm93

 

Clean it up and see if it works, if it does replace the hose and you should be good to go, if it doesn't then test the voltages.

 

Never seen that blue grease before?
Sometime corrosion can turn a blue color?

But do as @Dm93 said, clean it and try it out.

 

Agreed, most likely corrosion from moisture.

 

@TnShooter @Dm93 cleaned out the inside of the housing, put everything back together but still nothing. Testing the connections and I’m not getting anything on my multimeter on any probes

 

What connections are you testing? Are you sure your meter has a good ground?

 

@Dm93 I tried another ground point and got 1 volt everywhere I probed. I hit TL1-3 and transfer case detection switch (red/blue)

 

Where are you checking from?
The actuator or the ECU?
Also, the actuator needs to be plugged in for testing.
You can test any of the connection with anything unhooked.
(Not and get the correct voltage readings anyways)

 

Interesting the limit switches should be 0v or 12V, is this at the actuator or the ECU?

With the actuator unplugged TL1, 2, and 3 should all be 12v unless a wire is shorted or the module is bad.

 

Yeah, you can test them that way.
But they won’t correlate with the values in the chart.
If OP is even going by the Guide in the link above?

This chart

 

@TnShooter @Dm93 I'm testing at the ecu, actuator was put back together and plugged in before I tested anything. I’m not the best when it comes to figuring out electrical problems, that aspect of tinkering has always gotten away from me unfortunately

 

I think I'd unplug the 4wd actuator and see if you still get 1v on TL1 2 and 3