No 4WD

Hello! So my 4WD stopped working a while back and I can’t seem to figure out the cause… The green dash light flashes constantly and when I turn the 4WD switch nothing happens. I’ve checked all fuses and replaced the front diff actuator, transfer case actuator, and the CCM… Nothing. Any ideas?

 

Check your limit switch voltages at the 4wd ECU as outlined in the thread below and post your results so we can see what part or the system is having an issue.
https://www.tacomaworld.com/threads/4wd-system-operation-help-thread.742420/

 

Watching

 

I finally got around to checking the limit switch voltages

 

Is that a 0v on ADD in 2H?

 

Yes, 0v on ADD in 2H. Sorry for my terrible handwriting

 

No problem.
Looks like we need to first see if the ADD is locked in, you need to get under the truck and see if you can turn the front driveshaft.
If the front driveshaft turns free then we need to unplug the ADD Actuator and verify ADD goes to 12v, if the front driveshaft doesn't turn freely then your probably gona have to pull the ADD Actuator and see why it's stuck in the locked position.

 

FWIW, you don’t have to have the truck in neutral or on jack stands to turn the front driveshaft.
It should turn freely, in park, with the wheel on the ground.

Easy to check.

 

Thanks guys! I’ll check tomorrow and report back.

 

Ok, so the front driveshaft didn’t turn and I confirmed that the actuator is getting 12v. I pulled the ADD and it seems stuck. Should the lever move easily?

 

Did you pull the ADD actuator or Transfer case actuator?
The ADD uses a “fork” to slide the sleeve in the front axle.
The transfer case uses a gear to push the rod in and out on the transfer case.

If it was in fact the ADD you pulled. The rod (fork) won’t move easily.
The sleeve in the front differential should move freely.

 

I pulled the ADD actuator with the fork

 

The fork should not move freely.
It only moves when it’s powered.
It slides the sleeve over to lock into 4WD.

 

This^
You can also leave the ADD off the front diff and see if the system shifts in and out like it should.

 

That’s exactly what I did. I took it off completely and inspected it; all seems fine. So I plugged it in and just let it hang there while I tested it. Seemed to work! I put it all back together and it H4 will now engage although the light still flashes and when I try L4 it continuously beeps and flashes… Not sure where to go from here.

 

You must have the clutch fully depressed and be under 2 mph to shift into and out of 4L.

 

Yup, that’s exactly what I did. I even creeped back in reverse a bit, then back forward trying to get it to engage. No luck. With the 4H light still flashing (even though I can hear and feel it engage) and then the 4L flashing and beeping I assume something is still wrong. Any ideas?

 

So the 4H light keeps flashing in 4H but it feels like it's in 4wd?

 

Exactly!

 

So you know the ADD works... that is good.

You indicated you removed the tcase actuator. Did you replace just the actuator part external to the tcase or the entire part (requires splitting the case)?


From the data in table above you posted , it looks like the gear inside the tcase actuator cover isn't correctly positioned. I'd try the following : (a) make sure the ADD is in the 2wd position (ie front drive shaft spins when front wheels on the ground, (b) make sure the switch in the cab is set to 2H, (c) make sure the actuator rod entering entering the tcase is pushed all the way into the case - this is setting the tcase to 2H. If the truck is in 2H then you don't need to mess around with the rod position. 2H means the rod is all the way into the tcase. ., (d) set the position of the plastic gear correctly in the actuator and remeasure the voltages to make sure they are correct . See link in post #2 above.

EDIT; in addition to the information in link in post #2 above, this is a decent video on how to get access to the plastic gear inside the tcase actuator that needs to be correctly positioned.

https://youtu.be/_retFUemr_g