4wd not working

Studying this now...
Sorry I was off all day

 

So I was having similar issues, when I put the truck in 4x4 it would make the nosies but thr light would stay blinking, meaning it has not detected a full engage. Sometimes driving for awhile it would stop or if I hit thr add it would work. This is known issue for these. So I decided to buy a new one and change it.

You really need to pay attention when reinstalling it that you get the fork in the slot, otherwise it does nothing. After I changed it, I took it for a drive but I was still having thr issue. But this time, it would flash for only short bit after changing and then go in. This continued until I did a full sequence of 2wd -> 4wd hi -> 4wd lo. After doing this it seems to be working as it should the other thing I did was change my transfer case fluids and that did improve motions slightly as well.

When i was getting thr 2wd 4wd change error on thr screen after replacing it. this happened when I unplugged the module with the truck on. What I did to fix this, as you are most likely now in 4wd and can't get back into 2wd, was to stop on a incline and shut the truck off while in D or R (depending on direction pointed) then while still holding the brake, start truck let off brake and turn switch to 2wd.

With thr first snow in BC, I didn't want to have to deal with issues anymore. And fingers crossed I'm still all good.

 

I can get back into 2wd i just have to shut truck off then turn back on

 

When you get it into 4hi, it has 100% engaged right? You are just left with the indicator flashing.

 

It use to yes but now after installing the new ADD I don’t think it is fully engaging anymore

 

When you removed the oem modulator, were you in 2wd or 4wd? When I did mine thr first time I think I missed thr notch for thr arm. And when I pulled it back out, thr arm was more in thr middle of thr opening. When I was trialing the new one, not mounted to diff, when I turned the dial it was move one way then back to the middle and display the flash or error on the screen. What I had todo, was move the fork over to the (I think it was passenger side) to be in 2wd position then carefully reinstall to the diff. After I did this, I haven't had anything wrong........so far...

 

I changed the actuator while in 2wd and fork was to passenger side. Yea I may end up pulling the front add back off as big of a pain as it is and just double checking that it’s properly seated on the notch but I’m pretty sure it was. Also while I have it out I’d like to try turning the dial to 4wd and see if I still get that 2wd to 4wd error with the actuator out off the diff. I’m frigging lost with these electronics. Wish it was old school with manual 4wd shifter

 

I need to revise the instructions in that other thread a bit for the future... sorry...

Let me just first verify that the measurements and pin numbers for the ADD measurements are taken at the ADD actuator itself.
From your readings, it APPEARS to be the issue is in the 'ADD' signal from the ADD pin 3.

For now my suggestion is to dont think about the transfer actuator at all for the moment, all those readings looked good.
Please double check the following measurement:
Resistance Pin 3 to Pin 6 on the ADD, as measured at the ADD.
First check in 2hi (with truck happy) and then check in 4hi (after shutting off truck)

It should be
open (infinite ohms) Pin 3 to Pin 6 in 2hi
and grounded Pin 3 to Pin 6(closed, 0 ohms) in 4wd

If you dont get the above readings (I believe you will have open for both conditions) there is almost certainly something wrong on/with the ADD.

If you dont get the above readings, I would personally unbolt the ADD, but plug in the ADD electrically, and operate the truck from 2hi to 4hi... Verify the actuator is moving, and see if you can determine why Pin 3 isnt reading correctly.

My best suggestion

 

Yep, I think its a good plan...
Dont bolt it back in until you can make the truck electrically go into 4wd and 4lo...

 

My issue with trying todo it without having the add mounted was that it would not stay in place. Unless it was installed therefore giving errors.

 

Even with some one else holding the ADD while you turn on truck and switch to 4hi?

 

Didn't try with anybody else. Nobody around at the time. But worth a shot. You do want to make sure that the arm is all the way over before installing it. That is what my issue seemed to be.

 

I think it was determined that the arm sitting 100% one direction for the other would case errors, while anywhere else would cause it to home itself and match the switch position for 2H/4H

 

My issue is now fixed. My new A.D.D actuator was faulty and not working when out side of the diff so tried my old actuator and was working out side of the diff. so reinstalled it and light was still flashing but decided to hit the actuator a few times with a rubber mallet and bomb it popped right into 4wd and tested 4 low and bomb clicked in. Tested it like 20times after that and goes in and out with ease. The actuator was sitting at passenger side when installing it so no actuator does not sit in the middle @minium . All the actuator does is more a sleeve from passenger side to the middle to lock then reverse to unlock so not sure why it would be in the middle. I want to thank everyone on this forum who helped me out and a big thanks to @BigWhiteTRD for all your help saved me a lot of money from taking it somewhere which I was close to doing.

 

Your welcome, although not sure I was that much help in the end.
Thanks for coming back and giving the update... helps us learn so we can be better educated the next time.

Any idea why the 'new' ADD was bad?
Was it used or new from dealer, or an aftermarket unit. Might suggest people electrically test the new actuator with the truck before bolting it up, based on what you experienced.

 

It was a brand new after market unit from rockauto (first part I've got off of them that has been bad) not sure why but the fork on the actuator would not move when plugged into my truck hanging out of the diff but when I then tried my old actuator the one I repaired, the fork moved and 4wd light went solid on my dash.

 

Interesting
Thanks
Will try to give people a heads up when I can, to test before install.

 

thanks to the OP who responded with the results, way too many on here who ask for help and then dont tell us what the fix is or was. Dang aftermarket parts...

 

For clarity on this statement, I didn’t explain it very well and if anyone reads this in the future for troubleshooting - I was referencing post 12 in the troubleshooting thread here: https://www.tacomaworld.com/threads...g-transfer-case-and-add.578262/#post-24403465

This suggests that it just can’t be driven all the way in either direction or it will error, any other state and it will self correct/drive by the ECU and home itself.

Glad you got it fixed, nothing worse than ruling out a component based on replacing a bad part with a defective one. There is even a YouTube video showing a similar repair after the customer replaced their ADD with a Dorman and ruled out the ADD as a result, only to replace it with a factory Toyota part and shows the Dorman was also DOA out of the box.

Also thank you for posting a follow up, all to often this doesn’t happen.

 

Good to hear things are resolved and even better to see it come full circle with a good description of what was happening.