electronic ADD toubleshooting

Posting this here because all though I have a Tundra, we share the same front diff and our transfer case is almost interchangeable.

I need help. I'm getting frustrated and have a Moab trip this upcoming weekend.

I tried to engage 4wd by pressing the 4hi button, and got the dreaded 4hi blink. It was not constant, but only when the 4hi button was depressed indicating that it did not engage. I used 4wd a month ago, use it at least once monthly and haven't had an issue in years since I found a cracked breather hose on the front actuator that allowed water intrusion.

When pressing 4hi, both my actuators are making noise like they're trying to work but I still have the 4hi blink and am stuck in 2wd. I pulled both actuators. The front looked great but the transfer case actuator had some corrosion and a cracked breather hose. I was sure this was the issue like I had before. I cleaned a little corrosion, regreased and re installed it.

4hi and 4lo instantly flashed, so I took the rear actuator off and moved the round gear to a more neutral position and reinstalled since I felt like I may have messed that up. The 4hi and 4lo flash went away. It still would not engage 4wd and 4hi blinked as it did before.

After work today I got to more troubleshooting and found this article on installing the transfer case actuator - http://www.yotatech.com/how-tos/a/toyota-tundra-how-to-replace-transfer-case-motor-actuator-414483

I knew I did this wrong, so I pulled it and the spring on the round gear under the plastic cover was under a ton of tension and spun the plastic cover around with it as soon as it was unbolted. I removed the metal part of the actuator and pushed the toothed shaft all the way forward to make sure it was in 2wd as per the article, and then installed the round gear, all the way rotated CCW up against the stop with the fingers in about the 3:00 position as the article says.

Now I suddenly have a flashing 4hi light that I did not have on my commute today. I changed the position of the round gear about 50x, and the blinking 4hi light did not go away. According to the article, this would mean the truck doesn't know it's in 2wd.

Now with the 4hi light on, pressing the 4hi button does not make the actuators make any noise as if they are trying to operate.

I jacked the entire truck, and had someone put it in gear and try pushing the 4hi button. Pushing the button did nothing, but I did notice that the front driveshaft is constantly spinning.

I am definitely not in 4wd because I have no binding in the front end.

It seems to me that the switches must be working since the actuators made noise when I tried to actuate them before I had the 4hi light constantly on. I have not troubleshot them yet, but will pick up a multimeter tonight.

Does it seems possible that since the front driveshaft is spinning, the transfer case actuator is engaged? I am not sure how it would be in 4wd since I am 100% certain that I pushed the toothed shaft all the way forward.

Could the front actuator be stuck?

Any ideas of what to troubleshoot?

 

Yeah beings the drive line is spinning the transfer case should be engaged and working. It must be the ADD at the diff not wanting to cooperate...

 

Not necessarily. If the front driveshaft is spinning, the. actuator could be engaged, but the tcase actuator be the issue. I would jack the Truck up and see if the front driveshaft will spin separate from the rear. If it does, then the issue is in the tcase. If the shaft won't spin separate, the it's in the front add motor.

 

Both front and rear shafts spin simultaneously.

 

Before I had got home from work today I had already said fuck it, and was ready to take tomorrow off work and swap a manual t-case in and lock the front actuator. I crawled under the truck, grabbed the front driveshaft and turned it about a quarter turn and it locked. It would no longer move. I pulled the t-case actuator again to have one more go at lining it up. I reinstalled it, started the truck, and 4wd is now working as it should.

 

Well I may have spoke too soon. I went in an out of 4hi and 4lo about 5 times, on pavement, and then parked the truck. All was good. Left my house an hour later and hit the 4hi button and 4hi and 4lo both start flashing.

 

Did some more troubleshooting and I'm done with it. 7 manual 4runner transfer cases within 30 miles of me.

 

Ahh good point...

 

Ha! 12 mile drive to work this morning. Mile 11 lights went out. 4wd engages and disengages fine. For now.

 

Got the manual case in. I'll post some info on it in the next couple days in case anyone references this thread in the future.



Looks pretty good seeing as how you could never get the V8 with a manual case from the factory!

 

I'll post this here in case anybody comes across it in the future.

So- first of all, thanks to Sal(Delatorre), Mike(Dyogim), Jose(Toyotech), and my buddy Taylor for helping me bench press this thing up and into place. I'll do a quick half-assed writeup of how I did it in case anyone is looking to do the same in the future.




The 4 runner case is the way to go. Specifically a 96-99 V6 auto SR5 J-shift transfer case. One without any electronic buttons on the side, and with a 23 spline coupler. This is what the 23 spline coupler looks like, with two "missing teeth".



To get the old transfer case out, drain the oil and unhook the electronics. Three plugs on the actuator, unbolt the one 12mm bolt and remove the entire speed sensor on the right rear of the case as you look at it from the back, and the brackets for wiring harnesses on both sides. Unbolt the drivelines from the transfer case and get them out of the way. The transmission needs to be supported with a jack so the crossmember can be removed. Annoyingly it only needs to be removed to get one bolt in and out of the transfer case, but that's the way it goes. There are 8 bolts that hold the transfer case to the adapter at the back of the transmission. After they are out my transfer case was still solidly attached. I gave it a few whaps with a hammer on the lip on the backside and was able to slide it off. The rear seal at the back of my transmission had a nick in it which let fluid come through that turned into a dry, white powdery dust.




I replaced the seal. Part number is 9031140007 if anyone needs it in the future.

I got a 2.5" holesaw to make the hole for the shifter. I think this is the absolute smallest size you can make this hole and still be able to get the shift lever snap ring in. I just measured off the back of the adapter to figure out where to put it.



I removed the shifter instead of the entire top plate. It is held in place with a snap ring.



I pulled my 4wd fuse in the cab to keep my 4hi and 4lo lights from flashing and clipped the wires coming out of the three positioning sensors on the manual t-case for 2hi, 4hi and 4 lo. Put a little grease on the coupler splines of the new transfer case and manipulate the output on the back of the transfer case to get it lined up. Make sure you don't hit the seal while it's going in. All while laying on your back and bench pressing it up and into place! The jack I had wouldn't go high enough to get it up to where it needed to be, but it was actually easier to get it in than it was to get it off. Reinstall everything you took apart earlier. There is a cap on the 4runner case where the speed sensor goes. Remove the cap and throw your speed sensor in from your old case. Throw some electrical tape around the three plugs for your old actuator that is no longer there and tuck them up and out of the way above the t-case. Take your old actuator out back and shoot it with 9mm hollowpoints and then finish the rest of what you can find with a 12 gauge. Refill the case with oil.

It's kind of a PITA to get the snap ring back in, but after a dozen tries with a second set of hands we got it in place.



Now on to the front diff. It would be possible to wire up a switch to operate the front actuator, but I wanted to get rid of the electronics in the 4wd system completely. There is a shift fork in the front actuator that slides a sleeve over a gear for 4wd or slides the sleeve off of the gear for 2wd. The shift fork can be locked in place to keep the front in 4wd. With an open front diff and the transfer case in 2wd, this does NOT cause any binding on pavement! Once 4wd is engaged in the transfer case, you will get binding in the front end on pavement as usual. The only con I see to the locked actuator is drag since the front driveshaft is now constantly spinning which I guess could reduce your MPG by a hair.

To lock the shift fork, drain the oil in your front diff and remove the front actuator. Slide the shift fork all the way to the DRIVER side. Install a 3/8" hose clamp and clip the extra length. Do not make it so tight that the shift fork has no play up and down or it will give you a hell of a time getting back in.



Slide the locking sleeve in the housing over the gear. You can confirm that it is in the right position by spinning a tire and seeing the front driveshaft spin. The sleeve will be to the DRIVERS side to line up with the locked shift fork. Replace the word "passenger" with "driver" in this photo-



Add gasket maker to the clean actuator and slide the locked shift fork over the locking sleeve. Confirm that it is locked after installed by spining a tire and looking for the front driveshaft to spin. Install your bolts and refill the front diff. This website explains defeating the ADD in detail, but with passenger and driver sides opposite of what we have going on in our trucks and it should be the same with a 3rd gen 4runner and 1st gen Taco. http://www.4x4wire.com/toyota/tech/add/

Now, do whatever it takes to make it work on the inside of the cab. I cut up my doublecab center console and temporarily threw a goggle bag over the shifter to keep junk from falling in my new hole. I ordered a rubber shift boot with bezel today that I am going to install against the floor to keep the elements of of my carpet. I also ordered a fake leather universal shift boot to make something nice between the shift knob and the console itself.




Everything works as it should! You still have to be in neutral to shift into 4lo, but you can still shift from 2hi to 4hi on the fly. I am not sure yet if there is a top speed to that, but I have tested it up to 20mph and it works.

 

Awesome write up so far !!!!! will truly help others
I will add a little link https://www.tacomaworld.com/threads...er-case-in-the-2nd-gen-truck-write-up.345652/

 

For what it's worth, there was no need for the hose clamp on the front diff actuator. You can jumper the motor to spin it into the locked position and just leave it there. I have an electronic ADD actuator in my Tacoma and left it on the locked position for a few years wile I saved up parts for my current project. There is nothing to push the fork to the unlocked position. Even if there was, it would have to break the worm gear that operates it. I have never read any posts anywhere stating that something forced the shift fork out of position.