I had the same problem you did...stuck in 2 wheel drive with the blinking light. My problem ended up being a bad transfer case actuator. It was going to cost $1200 for the actuator and $800 to install it. I ended up getting a used transfer case and changing it myself. A whole lot quicker and cheaper=)

There are a total of 6. You found the 2 on the transfer case actuator. If youre on the passenger side of the transfer case you'll find 1 on top of the transfer case by the shift lever. It's tight up there and theres a vacuum line, so be careful of that and dont knock it loose. On the drivers side you have 2. You have to take the rear one out first then the front one. To put them back in start with the front one then the rear one. The other one one is on the front actuator(thats the other actuator youre looking for). Its right above the cross member in the front. Very tight up there. Its vacuum operated, not electrical like the transfer case one.
As far as checking your transfer case actuator, jack ur truck up off the ground(all 4 wheels). U apply 12v to the 2 pins on the bottom row on the right. Bottom row is the one further away from the actuator and the wires for those pins are thick solid green. Positive on one and Neg on the other. I dont remember which one will make it go in or out of 4wheel drive, but u reverse the Pos and Neg to do the opposite. If the Tcase actuator is bad u either wont hear any movement or you'll hear that constant clicking/grinding. After you do that, leave the connector unpluged. With the truck running and in gear, one of the front tires should be turning along with the back ones. Reverse the Pos and Neg and see if it comes out of 4wheel drive. If all that works, plug the connector back in. Make sure if the Tcase is in 2wheel drive the push button is not depressed. With the trucked still jacked up, see if you can push the button and make it go in 4WD. You should be able to hear the Tcase click and move. Lights on the dash should be solid at that time.

If non of that works, you may have a problem with the VSV which controls the vacuum actuator.

Also, Toyotapartszone.com has really good illustrations and parts pricing. I pulled this up to help you better locate the the sensors. Youll be looking at 84222B, C, D and E. 84222 no. 1 and no. 2 are the ones on the Tcase actuator which you already checked. http://www.utoyot8.com/FullImage.asp...6+TRANSMISSION

 

Thanks for the quick reply.

I tested transfer case actuator tonight with 12v, sure enough the little thing made a whirl noise, lasted a few seconds then clicked. when I reversed it did it again. From what I've gathered from this thread, that means the transfer actuator is okay.

Of note, I believe my front actuator is different then yours because I have a 2002, there isn't a switch on it. Also, there's a 6 wide plug that looks like the plug on my transfer case actuator. I've read that while older models are vacuum powered, 2002s are electric powered.
in fact, here's a picture of the two different front differential actuators:



I tested it tonight by connecting 12v to plugs 2 and 6 (here's a link) and it didn't do anything. I also checked the continuity on it and got nothing from it.. I think this means my front diff actuator (officially called the A.D.D. actuator) is bad. Still trying to piece it all together.. I may go to the stealership tomorrow to see if I can get a price estimate.



3. INSPECT A.D.D. ACTUATOR
(a) Disconnect the actuator connector.
(b) Measure the resistance between the terminals 2 and 6.
Standard resistance: 0.3 - 100 W
(c) Measure the resistance between the terminals 2 or 6 and
body ground.
Standard resistance: More than 0.5 MW
If the resistance value is not as specified, replace the actuator
assembly.

 

Well, I took it down to the toyota shop today to see if they could verify my front dif actuator was bad. They concluded that yes, they think it is the actuator.. new one is $1000 and it'll take $500 to put it in. Ouch!

I need to see if I can find any posts on how change this out or possibly take it apart and clean it. I know I'd read somewhere that it wasn't too difficult. Again, any help or ideas would be appreciated. Thanks.

 

I would say this is the same issue.

What you need to do is climb under the drivers side of the vehicle, just below where the 4WD lever is in the cab. There will be a silver and black actuator above you that has a 1.5" wide plug (disconnect it) and two grey plugs with connector wires (disconnect those also). Get a wrench and back the two switches that were connected to the two grey plugs. Get a multimeter and check those as described earlier in this thread.

If anything, the front one will be bad and have no continuity when depressed. If that's the case then for $58, you'll have a fix.

It's actually really easy to do.. just takes some patience and knuckle busting to get the two switches out.

 

Well atleast its not the Tcase actuator. Good news is it's fairly easy to replace the front actuator yourself. Theres 4 bolts that hold it in there. I replaced mine too while I was at it with everything else. Difference was mine was only $115. My recommendation would be to sign up for alldatadiy.com. It gives you step by step directions on how to replace parts and inspect them too. I think its only $27 bucks for a 1 year subscription.
As far as replacing it, this is what Alldatadiy for mine says. I cant imagine it would be much different. I would get the PN from Toyota and find it on toyotapartszone.com. It would save you a bundle from buying it at the stealership.

REPLACE A.D.D. ACTUATOR, IF NECESSARY
Remove the A.D.D. switch.
Remove the sleeve fork pin.
1) Using a hexagon wrench, remove the screw plug.



2) Using a pin punch and hammer, remove the pin through the hole of clutch case cover.
Separate A.D.D. actuator from clutch case cover and remove the sleeve fork.
1) Using a hexagon wrench, remove the screw plug.
2) Remove the spring seat, spring and steel ball.
3) Remove the 2 bolts and actuator from the clutch case cover.
4) Separate the actuator from the clutch case cover and remove the sleeve fork.
5) Remove the O-ring from the actuator.


Install the sleeve fork and A.D.D. actuator into the clutch case cover.
1) Install a new O-ring to the actuator.
2) Coat the O-ring with MP grease.
3) Place the sleeve fork and install the actuator to the clutch case cover.
4) Torque the 2 bolts.
Torque: 21 Nm (210 kgf.cm, 15 ft. lbs.)

5) Install the steel ball, spring and spring seat.
6) Coat the threads of screw plug with FIPG.
FIPG: Part No. 08826-00090, THREE BOND 1281 or equivalent

7) Using a hexagon wrench, install the screw plug.
Torque: 13 Nm (130 kgf.cm, 9 ft. lbs.)

Install the sleeve fork pin.
1) Using a pin punch and hammer, install the pin through the hole of clutch case cover.
2) Coat the threads of screw plug with FIPG.
FIPG: Part No. 08826-00090, THREE BOND 1281 or equivalent

3) Using a hexagon wrench, install the screw plug.
Torque: 20 Nm (200 kgf.cm, 14 ft. lbs.)

Install the A.D.D. switch. Install a new gasket and A.D.D. switch. Torque: 40 Nm (410 kgf.cm, 30 ft. lbs.)

 

It's going to take a 1 1/16" wrench.
Heres a pic of the '99 4runner LTD sensor locations

 

Honestly, this sounds way beyond my ability level. I wonder if it's something that if I buy the part I can take it to a local shop (non-dealership) and have them replace it for me?

Another question I have, the odd thing here to me is that (I just bought this truck) the front diff actuator looks fairly new to me. It's pretty clean and the screws are still shiny. I'm wondering if it's possible that the previous owner had it replaced or tried it himself.. but the dealership didn't know anything about it and I thought that would have been logged under the VIN.

I'm wondering if the skidplate that protects the actuator might possibly do that good of a job keeping it clean?

Is it possible that there's something else wrong with the transfer case or some other part and the actuator isn't the bad part here?

 

They would definitely be able to do it. More than likely they have Alldata for professional mechanics and would be able to run test on the actuator for you. I cant imagine it taking more than an hour for them to take the old one off and put the new one on...especially if I could do it.=) I would just bring it over there and talk with one of the mechanics and tell him your dilemma. What would be the cost of the actuator from toyotapartszone?

 

The part I believe is:

41400 ACTUATOR ASSY, DIFFERENTIAL VACUUM
Replaced by: **400-34013 **400-340122001.02- VZN185 1

$269.20

The "Replaced by: 400-34013" I think represents the fact that the new one isn't the old vacuum controlled unit. If you look up a earlier model 4runner it doesn't have that note on the part and it's cheaper.

41400 ACTUATOR ASSY, DIFFERENTIAL VACUUM
**400-35020 1995.11-2000.08 RZN185, VZN185 1

$149.82

By the way, for anyone looking.. I found the part under the "Powertrain/Chasis --> 43-01 Front Axle Housing & Differential" section.

$269 isn't bad in my book, I'd gladly pay someone for a few hours to get it installed correctly. Thanks for your help!

 

Check out Toyotapart.com. It's $256. Probably the difference in shipping.=/

 

So, I was able to find out who the former owner had servicing the vehicle and I called to get info on it. It turns out that they replaced the front actuator in January.' Apparently the truck was locked in 4WD and wouldn't come out. Sounds familiar, eh?

They told me that there's a motor inside the transfer case that controls the 4WD that needs replaced. Currently the motor is in the 2WD position and because it is bad it won't go into 4WD. They think the entire transfer case needs replaced (for $4000!).

Someone help me makes sense of this because I tested the actuator they replaced and when I apply 12V the differential doesn't do anything. I know I'm testing it correctly.. also, there's no resistance specified (another sign that the actuator is bad). Everything tells me that the actuator needs replaced but they just did that in January.

Is there some other part of this system that would stop the front actuator from working when I apply 12V? Anyone know what this motor is that they speak of that is inside the transfer case?

Thanks.

 

The Tcase actuator is attached to the back of the Tcase...same one that was bad on mine...I believe you already tested that one, right. In order to replace that they have to break the Tcase open and replace the actuator. You might be better off getting a used Tcase from a junk yard for around $400. But if you say the front actuator isnt moving then it might be a bad. I couldnt tell you how to test it since mine is vacuum actuated. Did you get on alldatadiy.com?

 

Alright, that's what I thought. I tested that actuator.. it works fine. I applied voltage to the pins it engaged, then swapped the leads and it disengaged. That motor works fine as far as I'm able to tell.

I'm taking it to the local guy I trust tomorrow.. we'll see what he has to say. Thanks.

 

Any luck with the actuator?

 

Thank you all for info and help with this frustrating situation. Been searching for info, pix of part, mechanics won't talk, still not sure exactly what am looking for directly. Cannot find anything detailed. Know I'm not paying dealer $2000 to fix what I'm not sure is main prob. Appreciate all your input as is helping more than I can find from anywhere! maybe will get some progress somehow. Much appreciation fellas! Runnerd-'03

 

I registered specifically to give thanks. i have been following this thread for a month and finally decided to act on the recommendations and suggestions mentioned on this thread to fix my flashing 4WD issue on my 2000 LTD.

My 4WD Issue:
My problem has been intermittent since I bought the vehicle new and I have always learned to work around it, but it was very annoying at times. It happened only once during my warranty period and I couldn't replicate the problem for the mechanic. The light occasionally seems to flash when I press the button to switch from AWD back to 2WD. I can feel the truck disgengage and properly get into 2WD, but the dash light will flash. When it is flashing I can't switch back into AWD or any of the 4WD modes. 99SC4Runner's explanation of how these switches communicate with 4WD computer makes a lot of sense.

The Fix:
Ok, so I am one of those lazy people who takes their truck to the dealer for everything, but my dealer is very reasonable (for the most part). Being non-mechanically inclined is an understatement. I usually make things much worse when I work on anything. My Toyota dealer does good work and charges a reasonable price. I just have to call around and they match the price of just about anyone. I usually save 50% or more. Plus, I only take my truck to see 1-2 mechanics that I have known for 10 years. I took my truck two weeks ago to the dealer to have them check out what is causing the flashing 4WD issue and get the problem fixed once and for all. My usual tech wasn't there, being impatient, I wound up getting a different guy at the dealer to look at it. 1.5 hours later he along with my service advisor came in and told me they didn't know what was the problem that it would cost $100 just to diagnose the problem. I told him about the switch that has been recommended here. He was convinced that it wasn't the problem. He HIGHLY suspected that I needed a new actuator ($1500). I declined and told him that I would get a second opinion. I bought the switch from their parts dept ($63) and drove home. I carefully looked at the images that Romey_d posted multiple times, but I didn't have a ramp or any jacks to get my big head under the vehicle. I took the truck to an import repair shop who had good reviews. They made me wait 2.5 hours and told me that the plastic housing on the switch was cracked. I suspect that they dropped it. The next day, I decided that I had enough and would go take my vehicle to see my usual tech. My dealer promptly replaced the part for free after I honestly told them what happened at what the other mechanic told me. My service advisor then had the part installed by my usual mechanic. When I went to pay the bill, I realized that my service advisor didn't charge me and did it for FREE. I couldn't believe it. My service advisor told me that he was pissed that the other tech had me wait 1.5 hrs and couldn't tell me what the problem was.

I drove the truck all week and putting it into and out of AWD and all of the 4WD modes. The system smoothly and consistently engages and disengages into AWD and 4WD. EVERYTHING WORKS GREAT! I couldn't believe it. I can't thank this site, members and the community enough.

Simon

 

Fixed switch ... They wanted 147$ here in Canada for that 84222-12010 switch.. I'm an electronic tech and in my arsenal I had a can of Deoxit which is a contact cleaner. Removed switch sprayed in while working swicth up and down. Success ... used my meter to test and switched EVERYTIME. re-installed and went for a drive..WAHOO for flashing 4wheel lights switches like new.
Repair cost 12$ for can of cleaner which i had anyway......
Thanks for all the posts big help and cost saving...

 

Hi Everyone,

I've been researching this problem all day as I'm having similar issues with my 2000 4Runner Ltd. I used the M/M switch to go to 4HI and could tell the front wheels have engaged, but now I can't get it back to 2HI and the dash light won't stop blinking.

However, there is also another wrinkle: when making tighter turns or turning while backing up, I can feel a lot of axle bind. My 4Runner has a rear diff lock which is disengaged, and my transfer case is still in the 2HI/4HI position (not 4L or 2L), so not sure why this would be the case. Perhaps somehow the center diff has been locked and won't disengage???

I'm not too mechanically inclined, but any help would be appreciated (or any suggestions of good mechanics in Calgary, Alberta). At this point in time, I need to get it out of 4WD (or unlock the center diff) so I can at least drive it as I don't want to cause anything to break from the axle bind.

Thanks very much for your help.

 

YYC.... same problem with everyone on this post... if you have a 27mm socket and ready to get dirty it's a easy fix.. Not sure about location on the 2000 4runner I have a 2002. But there are 2 actuators 1 in front of the transfer case the other on the back end of the transfer case. On my 2002 the switch that was bad was on the back actuator closest to the transfer case. I removed it sprayed some contact cleaner in the end of it worked it till the my meter showed that it was switching and voila it worked. Saved myself 147$ Canadian plus taxes... and has been working perfect for me. Good luck.. btw the switches are mounted on top of the actuator.. just look for wires leading to the switches and it doesn't hurt to spray contact cleaner in both. Just remember if it uses a 27mm socket to remove them you found the right ones.

 

Alright guys, my knee hit the 4wd button on my GFs 2000 4runner while driving back from work today and then the lights starting flashing & etc. I tried putting it in Neutral and switching it from 2-4wd but it seems like its stuck in 4wd. I will check out the sensors today (hopefully they are). Wish me luck, Rey.