2011 4WD light constantly flashing/blinking

I need some help with my 2011 4Runner. The 4WD indicator light blinks/flashes all the time. It just started out of the blue one day and has been this way for a few weeks. I don't think the truck will go into 4WD at all. I can move the shifter to 4H, but it doesn't appear to change anything. The light doesn't stop blinking and it still drives the same...doesn't feel like it's in 4WD at all.
I've read all kinds of threads about an actuator but I'm not quite sure where I need to be looking. I'm a self described "YouTube mechanic" and usually do all of the work on our other vehicles (Chevy) but this is my first ever Toyota so I'm flying kinda blind here. Just need some pointers to point me in the right direction of what to start looking at...preferably with pictures (or video).
Btw, I have the manual shifter not the electronic knob.

 

In my experience, this points to the ADD but I'd see what code is triggering the light. This will require a scanner that can read the 4WD module which will be something the dealer has. It will be a $100 or so diagnostic fee.

 

I would try to get a diagnosis scan, as @whippersnapper02 suggested. Some auto parts stores have scanners, and will usually scan it for free.

 

“The car care nut” youtube channel has a really good video on the 4runner 4wd system. From watching that video, Id guess you have an ADD problem, or if you ever shut off the vehicle while in the process of engaging 4wd, it can hang up. There are some switches in there that are old-school (sliding contacts, not micro switches). The system can get lost if it’s shut off when it’s stopped midway between the two contacts. Not sure if that was for the ADD or for the electric dial operated transfer cases.
Either way, the video he has is good for giving you an idea of possibilities.

 

I have a cheap bluetooth reader that I used with my phone to check the tranny temp when I changed the fluid a while ago. Maybe that will give me some information.

I love the Car Care Nut. I will definitely check out his video.

 

Thanks for the reference to the Car Care Nut.

This video explains it:

 

Is this 4wd module info that is communicated through the OBD system, or does it stand separate?

 

Thanks for finding it lol.

@bdbull, let us know what you end up finding. I’m curious about how ADD might fail (if that is your problem)

 

It's through OBD but requires a certain protocol for communication. A basic scanner won't be able to communicate with it.

 

does anyone know of an OBD app that has this cracked? I have the “Car Scanner” app, and havent seen any info regarding 4wd if I recall correctly.

 

Just wanted to update the thread...

My reader did not show anything helpful so I've made no progress on this. I do have a buddy that has a pretty expensive scan tool so I'm gonna try to get over to his place this weekend and see what we can find.

 

Had my buddy look at it over the weekend, but we didn't get anywhere. He got under it and couldn't see anything that seemed off. We think the next step is to see if there's any troubleshooting that can be done directly on the ADD. So I'm just gonna research that, and see what I can come up with.

 

Took the ADD off today and I think I may have found my problem. Lots of rust and there was even water in the housing. Doesn't look salvageable to me, so I guess I'm in the market for a new ADD module.

 

Bummer, but at least you found the problem. Did you do a lot of water crossing?

 

Absolutely no water crossing for me, but I don't know what the previous owner did. However, probably just coincidence but this problem did start after sitting in a torrential downpour a few weeks ago.

I'm gonna try to clean it up and bench test it to make sure it's dead. I found a good youtube that shows a guy doing that, so we'll see how that turns out.

 

It's dead. Applied power to it and not one bit of movement at all. Now to try to find the part to order.

 

Thanks for following up with your research and diagnosis. It’s really educational. I can’t tell from the pictures- if there’s water in the ADD could it be possible that there’s water in the diff oil?

 

Yeah, totally possible. I figured since I'm in here doing this I might as well change the diff oil since it's on my TODO list. The oil looked pretty good and I can't seem to see any water in it, but who knows. I'm sure there's at least a little in there. Now I'm just waiting for the part to be delivered. Will probably do the rear diff while I'm under there and have that fluid out anyway.

 

Happy to report that we are back in business. Got the new part delivered and installed today. Put it in and buttoned everything back up. No more flashing light and I was able to successfully put it into 4WD. Fingers crossed I'm calling this one done.

 

Good job, did you get a new ADD actuator from dealership or aftermarket?

 

I went aftermarket. I figured I'd roll the dice on aftermarket not knowing if that was definitely the problem plus the enormous price difference.

 

Good to know. Did you buy it at a regular autopartsstore? How much?
Also, I noticed that my ADD unit has what appears to be a breather line exiting the unit. I imagine it goes up to the area below the rear corner of the fuse box, where there are a couplenof breather valves tied togetjer. Did you see if the little breathers are moving up and down easily? The ADD may have died a natural death, but it made me wonder about the condition of the breather tube valve.

 

Bought it from

$53 Bicos 41400-35034 600-488 4WD Front Differential Vacuum Actuator Compatible with 4Runner FJ Cruiser Tacoma 41400-35033 41400-35031

Amazon for $73. It does have a breather tube coming out of it. The new part came with a new breather tube, but the inner diameter was too big so I reused the old one. I inspected the old one before I put it back on and it was in good shape. I plan to try to trace the line to see where it goes in the engine bay bc I can't figure out how else water got in there.

 

That’s weird, they describe it as vacuum actuated…i thought the electric motor inside does all the moving. I wonder if it’s not actually a breather, but a vacuum line? But the again, it seems like it would need a breather, like the rear locker actuators…hmmm

 

I think this one is entirely electric. There is a model that has two vacuum lines coming into it and it is vacuum actuated. I'm not sure what models/years that one is on, but that's what initially made this difficult for me. Most of the write-ups I found were around the vacuum actuated part and they confused me.

 

I think you’re right. This article shows a photo of an ADD with what appears to be space for a vacuum diaphragm.


So let me get this straight. The ADD disconnects the driver’s side axle from the differential. The passenger side axle and the front drive shaft are still connected to the differential. I understand that when the left front axle is disconnected, then the front drive shaft stops turning, but I’m having a hard time wrapping my head around it. Why doesn’t the front drive shaft get spun though the differential by the turning of the right front axle and wheel?

 

Ah, That makes sense. Thank you for taking the time to post about your repair.

 

Talking a vague guess based on weak memories of what I’ve read before, but I think it has to do with the “differentialing” action of the differential.

 

“Differentialing.” Nice wordsmithing! I understand that the purpose of the differential is to allow the drive shaft to distribute torque to both axles while allowing them to rotate at different speeds. But understanding this idea that disconnecting one axle from the diff stops the drive shaft from spinning even though it’s still connected through the diff to the other spinning axle — it’s like trying to say the alphabet backwards!

Can someone just whip up a 3D animation or whiteboard video to explain it? (/sarc)

 

I thought I understood what was happening so I started to respond, but as I thought more about it, I got that mental feeling you get when somebody says random numbers while you try to carefully count something.

Then I thought some more, and it felt like doing a big presentation on a zoom call while you hear your own echo a half second delayed.

Then I thought some more, and figured out I actually had no fricken idea what I was talking about. But I felt a need to word-smith a new word into existence because I still kinda suspected some sort of differentialanating action was occuring.

See?…makes perfect sense.