How To Trouble Shoot 4x4 Actuator

just wait til you put an FJ cruiser setup in and don’t have a worry in the world if your truck will shift into 4wd

 

It was a bad 4wd position switch on the tc. I pulled both the 4wd & Low4 switch to compare. The 4wd spring movement on the ball would easily compress flat. The Low4 would also go flat but with more effort. This made me think there has to be a spring inside that wears over many cycles. I bought a replacement from napa for the 4wd switch and when I tried to compress it, it would only compress half way not even flat. I put it it and tested it. The truck went into 4wd on time every time after the initial ecu click. It didn't even do that when the truck was new. The first thing I did was replace the front add because the vent tube was gashed open. The old motor was stiff as hell and can't even be opened as all screws are rusted solid. I tested the motor after a few days when it was sitting upside down and it smoothened out a lot. I think what happens in a lot of cases is that the switches lose spring tension and the 4wd starts to complete its cycle less and less until it won't work. Than like most guys we put off the troubleshooting for a year or about a week before a blizzard. Meanwhile the front add starts to slowly seize/stiffen out. I plan on posting some photos in the next couple days because there was zero information on the web on how to identify a bad switch. I want to compare the 4lo switch in there to a new one so I can identify the difference. I'm glad I didn't have to gut open the tc actuator. But if i had I would have inserted a thin rod thru the vent hole to keep the gearing in place so I could mark it when I would slide the front casing down. It seems a few people had issues with the gear set falling out and getting the gears out of setting.

 

My actuator only works depending on the temperature. If the vehicle is under 35f 4wd hi and low will engage. If I leave it parked in my garage at 60f it will NOT engage. Once I have it engaged I can disengage at any time. I spent a week testing this (this past winter) and 35f seems to be the magic spot. If I knew we had snow in the forecast but it was still supposed to get into the 40's I would alarm clock for 3-4am and engage the 4wd.

Knowing that hot mess, where would you start to look?

**Edit**

Propped my phone up to see what noise was coming from where. This is coming from the motor off the back of the tcase.. I believe

https://youtu.be/Mzhig92CKZI

 

That sounds like an electrical short to me. I would first narrow it down if its a tc case issue ( most likely with that noise ) or front add issue. Everyone says to jack up the car and see if your driveshaft from the tease spins in 4wd. I just duct tape my phone aimed at the tc case shaft and recorded it as I went thru the 4wd at low speed. If the shaft spins to the front even at 60f than its the add, if it doesn't its the tcase. In my situation i just replaced the add and tested thru it pins it moved so I knew it was the tcase issue. I would check your wiring and connections for corrosion or any kind of debris. Def check your vent line coming from the tc actuator for any holes.

 

I pulled my front actuator apart and low and behold, lots of corrosion. I ordered a new one from Toyota and it has a vacuum line on it. Then I check my old one, no vacuum line but a port on the actuator and an open hole allowing moisture in. No wonder there was corrosion. Where does the vacuum line go? Can I can it off?

 

I'm willing to bet your old vacuum line cap snapped off. It's very fragile. The vent goes up to the top of the engine bay along with the front differential vent, by the battery.

 

Yea its on a clip next to another vent line. Looks like a thimble

 

It just a vent to space?

 

yes, the great outer space.

 

I went out and snag a pic. You can see both vents here.

 

cool, thanks.

 

I got my front diff swapped after regearing and a new actuator. Front add works as designed. I'm positive the lack of vent tube allowed moisture in and corroded/shorted the internals. Vent tube goes to the hood hinge now.

 

I followed my front add vent tube and found that the line was gashed open because it was rubbing on a pressure clamp that had its edges rubbing on the tube. I wonder how many cases like that occur from the factory over time.

 

Just passing it forward. Many thanks to all of the information on this forum.

Had the same troubles as described. 4wd light started randomly blinking and would not engage. I knew I was trapped in 2wd but could not get the light to stop blinking or engage 4wd.

Pulled the front diff, soldered, cleaned, changed oil, and reassembled. It worked. Had 4wd engage no problem for an entire day on the trails after that.

Next day, roll up to the trailhead with a group and that damn blinking light came back. Couldn’t do anything about it and drove home to diagnose. Super embarrassing. This time around, my 4wd would remain blinking but I could feel the system engaging and also felt tight steering despite the 4wd light still blinking (making me assume I was in 4wd). Also I could engage 2wd by shutting down the engine and flipping over and starting back up.

Started to feel electrical or computer based so I started pulling all the connections and cleaning them, multiple factory resets. Nothing worked.

Finally I tried smacking the ADD with a mallet while engaging the 4wd. Amazingly this worked. Every time it would get stuck blinking, I would smack it and it would go green and allow me into 4hi and then into 4lo. It kept getting stick but after a few rounds of this smacking, the 4wd engaged on and off easily.

Really not sure what’s going on but it leads me to assume that the problem is definitely localized to the ADD unit itself as it responds to each smack. Assuming that there’s a part (possibly gears or mechanism in there) sticking each time that took a few repetitions to unstick.

Have a new ADD on the way already and I’m assuming that this would have also fixed the problem. Might solder that new one and see what happens as a cause and effect.

Hope this helps someone. I know how infuriating this problem is for people who wheel frequently so feel free to PM me.

 

I think what happens is the contact points beging to rust from moisture or hole in vent line and corrosIon is a very poor conductor. But always check the vent line all the way thru.

 

yeah I forgot to mention, to start it all, when I initially had the problem, my breather hose was disconnected and I had about a cup full of water in the unit. That was definitely the cause of the issue to start.

 

I just received my replacement actuator. Silly question. When I removed the old actuator, the fork was over to the passenger side. When I unboxed the new one, the fork is to the drivers side. How do I move it over?

I took the old one apart. It looks really good inside, but the gears were super stiff to get turning.

 

just move the collar inside the ADD tube to the drivers side before you install.

 

I knew it would be something that easy! I was worried that would lock it in 4wd or something. Thanks!

 

It works! Thanks for the help! I’m going to keep the old one just in case.