Cannot shift into 2WD but can shift between 4lo and 4high

I read a few hundred threads on similar problems, but mine seems to be the reverse with everyone else not being able to shift into 4hi or more often 4lo where I can shift between 4hi and 4lo with no problem but cannot get it back into 2wd despite trying every trick I could think of and all all of the ones I found in the forums. I have a 2005 manual transmission single cab 4x4 with 205,000 miles.

It has been about 2-3 weeks since I used 4wd and the problem is not surprising since I drove through about 40 miles of water up to and occasionally over the front bumper. (We had 26 inches of rain in a single day and more on the following days). Immediately after the flood I had changed the oil in both differentials, transfer case, and transmission (Redline MT90 in the transfer case and transmission and cheaper stuff in the differentials).

So, if it can shift between 4lo and 4 high but not into 2wd, should I be tearing into the ADD (front diff actuator) or the transfer case actuator?

Many thanks!!!!

 

I believe it's the ADD. The electrical contacts are probably corroded, very common problem as they are not soldered, contact is made by simple pressure as i understand it.

@blackhawke88 has been in the ADD, maybe he can advise. I think he made a thread on it a while back.

 

I found his thread here:

https://www.tacomaworld.com/threads/how-to-trouble-shoot-4x4-actuator.263525/

 

yup, not sure if the factory trouble shoot guide is still available anywhere, but you should be able to test the connectivity of the actuator connector to be sure if there is indeed a connectivity or not before you go in and take everything apart. If anyone has a good link or source of the factory trouble shoot guide, it would be helpful

 

Well, I started with the ADD. My ADD is so clean inside it could pass for being straight out of the factory. Contacts looked good so I did not solder them. I connected a 12v battery to the motor and the motor was ok. Had to watch all my expensive recently changed diff oil pour out. I guess I need to get hold of some fipg sealant somehow so I can put it back together and go back to the drawing board.

 

My ADD removal process was:
1) jack up truck and put on jack stands
2) remove both skid plates
3) carefully disconnect wire harness and breather tube on the ADD
4) with a 19MM wrench on top for backup and a 22MM socket, remove the two bolts for the front differential supports
5) with a 12MM socket and a very long extension it was possible to come from above and unbolt the top two bolts on the ADD without any u-joints or resorting to 1/4 inch wrenches as others said. You have to start several inches to the side and then slide it over to get it in line with the bolts because the space directly inline was wide enough to get the extension through but not the socket.
6) drain differential first preferably or have oil pan underneath when you pull off the ADD
7) Pull off ADD. Unscrew the 4 screws.
8) Mine looked good. Motor was functional. Contacts looked good. Sleeve inside differential seemed frozen initially. Resorted to crowbar after which it moved ok.
9) I let it drain overnight which apparently still wasn't long enough because even after draining overnight and cleaning it 5 times, oil dripping ruined my new FIPG seal and I had to start over.
will finish updating later...

 

Sorry to hear that... There is a step by step Toyota trouble shooting guide... I might be able to get it to you Monday

 

Thanks for the offer. I found the troubleshooting guide in the other thread, though it is amazingly poorly written for something from Toyota. I won't be able to do anything with it until I can catch a ride to get my multimeter. I am going to take apart my transfer case actuator in the meantime.

 

Dang, sorry you're having to go through that. Let us know how it turns out, bud.

 

What is happening when you try to go into 2wd, does the light just keep blinking but never go out? If you have already ruled out the ADD motor then that leaves the transfer case motor and a few limit switches as possibilities.... and I suppose the 4wd ECU itself which is less likely if you feel it's related to the water crossings.

 

Problem solved. The transfer case actuator was full of water and the outermost trace was corroded. I didn't even take the actuator off the transfer case, I just removed the plastic cover held by (3) 10 mm bolts. Putting it back together was another story entirely. It was a ROYAL PAIN to get the gears lined up to put back together. It probably would have been easier to put back together if I had just taken the whole thing off, but I didn't have to change the gear lube again this way (since it was just changed a few weeks ago with $$$ Redline MT-90).

I am pretty sure that the water came in because of the vent hose. Unlike the differential actuator vent hose which was so tight I could not pull it off by hand, the vent hose for the transfer case actuator on my truck was flared on the inside with grooves making for an extremely loose fit not to mention the grooves themselves would provide an avenue for water to get in. I trimmed half of the flared portion off to get a tighter fit when I reassembled it. The transfer case actuator also uses an O-ring to seal rather than FIPG so that is a potential source of leaks as well.
This is what the flared vent hose looked like: I forgot to take a picture of the corrosion on the trace, but i sanded out the corrosion and then built it back up with solder like this:
.
At this point I was really wishing I had used less solder because sanding it down was a PITA. I end up going at it with a big round grinding bit on a Die grinder for half an hour. The problem was that the solder would not grind. It was more like it would partially remelt and then spread out to the point that by the time I was done it had spread all the way to the next trace and I had to trim it back with a utility knife since it was a thin layer by that time. Not pretty but it is functional:
I initially recoated all the traces with Permatex dielectric grease (which I had in my truck for a few months) but then removed it because the Permatex Dielectric grease had the stickyness and consistency of Elmer's glue after it has had a few seconds to dry. I am guessing it must have been designed for things that are not supposed to move much. The butter-looking grease Toyota had used was more like the consistency of butter and not sticky so I cannibalized some of the extra yellow grease from other parts to coat the traces. Not sure if it will be enough grease for the long term but at least it works for now.

Also, for those of you whose problem is the A.D.D. (front differential actuator) instead of the transfer case actuator, you do not have to scream and curse at those top two bolts or use u-joints or 1/4 inch adapters as I have seen so many people post. I used a 10" Craftsman straight extension with a regular 3/8 ratchet. The extension does fit through the skinny space above the brace but the socket does not unless you start about 4 or 5 inches to the side where there is enough space to get the socket through and then slide it to the side until it is directly in line with the bolts you want to remove (this assumes you have removed the two bolts for the front differential supports which drops it down a couple inches putting that skinny space above the brace directly in line with the two bolts you want to remove. Easy as pie with no cursing.

 

Wow! So glad you fixed it! Very detailed resolution as well!

 

I would not have attempted it without the threads other people posted, so I wanted to make it detailed so perhaps it will help someone else. Thanks everyone!

 

Nice fix, I like how you got creative rather than just buying a new part!

 

Toyotas yellow di-electric grease dries out over time. Permatex is a better option. I've rebuilt both this actuator and the rear locker actuator now. Toyota claims both are non-serviceable parts and want big dollars for replacements.