sandfantom

After reading through all 18 pages of this thread I was hoping to find some one who has had the same problem as I have but to no avail. Maybe no one has run across this fix yet.

My wife has an 01 4runner Sport, auto trans, 4x4 AWD/4WD T/case. She started having the same blinking light, sticking in 4wd problems as every one else here. After much time on the interwebs I found a lot of info on this problem but no real solutions. I checked all of my switches and actuators and all seem to work, just not together as they should.

Long story short, I never really could find a wiring schematic for an 01 so I had to off the one for the 99. What I ended up doing was putting in a switch that grounds the #19 wire out of the 4WD ECU. This has so far solved my problems with the sticking in gear. Any time I have to shift into AWD or 4WD and the light starts blinking I just flip the switch on and off and every thing shifts as it should. So far I have not had any problems shifting in or out of gear.

I hope this is a temporary fix and I can find the real problem, but so far this is working.

Below is the wiring diagram of the 99 system I think, if some one has a diagram of an 01 I would like to have it.






If anyone has any more questions on my temp fix I would be glad to share what I have done. Or maybe some one has the permanent fix and that would be great.

sandfantom

TheDurk

Here is the EWD for an '02. It should be closer as '01 and '02 both have the VSC/TRAC and electric ADD actuator (instead of vacuum) and the '99 has neither. It is probably exact as I don't think there were any changes between '01 and '02.

The 'fix' you have identified really gets you no closer to a permanent fix as you have done nothing to identify the source of the problem, merely by-passed it. Simply put, there are a number of conditions required for the 4wd ECU to energize the actuator. You have to find which one is absent.

I can't help you more than that as I have never messed with the VSC/TRAC system and I am happy to keep it that way.

sandfantom

TheDirk

Thanks much for the diagram, it is much appreciated.

You are exactly right about my "fix", it is only temporary until I find the real problem. I guess I really shouldn't call it a "fix".

The switch just saves me the time and effort to get under the truck in the snow and mud to shift the t-case back to 2wd.

bakerbake

Alright guys so i read through all of this thread and I ran into an odd problem with my vacuum lines. when the vehicle first starts I can shift into 4hi or 2wd (lights still flashing the whole time) and the vacuum lines will switch. But after the first switch/shift if i try to shift it the other way, the vacuum lines do not alternate. does this mean my 4x4 computer is on the fritz? The lights flash no matter what so I'm a little lost on that. Thanks for all the great info on this thread! ITs a 99 limited by the way

RobT2k

Thanks for all the info in this thread! I was able to fix my 99 limited with the $36 sensor replacement from the first few pages.
Yotatech still coming through for me after all these years!!!

99SC4Runner

bakerbake,

You should test your front ADD actuator and make sure it moves both directions. Also, check the vacuum lines going down there to ensure there are no vacuum leaks in them.

taylorv817

Hi 99SC4runner.

I have changed out all 5 sensor switch on my transmission and transfer case. I bought this car from a small dealer and someone took out the 4wd bulbs from the dash. Long story short i put in new bulbs and new that the light started to flash. I just wanted to know how do you jump pin 2 & 3 on the actuator? Did you put positive on 2 and negative on 3 first or you ground to the frame and put positive to 2 or 3? I can't believe all 5 sensor switch did not give me tone after testing.

taylorv817

u there?

TheDurk

It is essential to post your model and year to get specific help like that.

Actuators run in both directions. To jump 12V to them, just put 12+ to one motor lead and chassis or battery ground to the other and blip it. If it moves keep going. If it doesn't move, reverse them. I can't confirm pin #'s without knowing model and year. If you are talking about the electric ADD on '01-'02 4Runners (and I assume some Taco's), then here is TFM:

TheDurk

If you are talking about T-case actuator, here that is:

taylorv817

Mine is a 1999 v6 3.4. I checked all that and the add vsv solenoid is good

TheDurk

So, which actuator are you talking about? If you are talking about the ADD, you don't jump anything to check it--you just switch the ADD hoses from one VSV to the other in 2wd with the engine running. The front shaft should rotate by hand before the switch and lock-up after. If not, bad actuator or other problem in the diff.

taylorv817

That was what I was trying to ask 99sc member. I was wondering how did he send the 12 volt on the actuator on the transfer case? Did he put negative on pin 2 and positive on pin 3 or vise versa. I'm sure the ADD and everything else is good. I did not get any ohm reading from pin 2 and 3. Some manual stated that you needed like 0.3 ohms to 100 ohms at least.
Right now it comes down to the awd ecu, relay or actuator arm. I can't believe i bought this lemon.

99SC4Runner

To jumper pins 2 & 3 on the t-case actuator, I used a 12v car battery charger set on 2 amp and I had the charger positive and negative battery leads connected to some 14 ga automotive wire. Then I just carefully put the positive on pin 2 and the negative on pin 3 to force the actuator to go into 4wd mode. Then reverse the leads on the pins and force it to go into 2wd mode. When it goes into 2wd mode, if you have the front tires off the ground you should be able to rotate them without turning the front driveshaft.

PS. I do have a good normal functioning 4wd ecu if you end up needing one.

GhostRiver40

Just posting to say thanks to 99SC4Runner and everyone who has contributed to providing the quality info in this thread! And provide my experience with the issue in case it can help someone in someway.

This week the snow started to fall as it tends to do here in Alberta. I put my 99LTD in AWD via the button and I was instantly in 4wd limbo. I could feel that the font end was locked in and have to drive quite a few KMs daily to and from work so in a panic I googled the problem and found this thread. I then immediately ordered the switch/sensor for the front from the dealership w/o testing anything hoping it would solve my issue. It did not.
I then tested the sensor I had removed (like I should have done in the first place) and it was working fine.

My next step was to be sure the rear actuator was functioning and eliminate what seems to be the worst case scenario. To do this I took two 10 foot lengths of 12 gauge wire and spliced on a spare set of pointed leads from a multimeter. On the other end I added some alligator clips (I also wired in a little in-line blade fuse on the positive lead as I would be working less than a foot from my face). I then hooked the alligator clips to the battery in my truck, disconnected the rear actuator and applied the neg to pin 3 and the pos to pin 2. The actuator moved out of 4wd.

With the actuator disconnected it was much easier to reach to two sensors behind/above it on the back end of the t-case. The first one I pulled out tested fine which was good because the connection did not match the spare sensor I had. The next one I pulled showed no continuity when I tested it, and it matched the extra working sensor! I replaced it and buttoned everything back up. When I fired up the 4runner everything was working perfectly.

Thanks again for the info everyone!

blockhead

4WD PROBLEM
2000 LTD with multimode and e-locker.
4WD (AWD) will not engage with MM switch and indicator light flashes.
4WD H4L will not engage with transfer case lever and indicator light flashes.
I am able to get it into L4 but I do not believe the front differential engages (with some circa 1970's gear grinding before they mesh before it goes into a Low 2 wheel drive).

It didn't fail overnight, it got worse and worse over a period of time.

Vacuum Switching Valve (Solenoid Assy., 4WD Control) #85440-35040
A.D.D. Indicator Switch is good
4WD Position Switch 1 on transfer case actuator is good.
4WD Position Switch 2 on transfer case actuator is good.

I've read about a ADD Relay, but I don't believe the LTD with 2-4 MM switch uses one. I've been using the FSM from NCTTORRA, but some of the instruction don't fit my truck such as the vacuum operated ADD. (The book only seems to show the electric)

Transfer Case to Actuator (#3641035051(40))Tube #044105001 replaced with no change.

Actuator Assembly, Differential Vacuum (A.D.D.) #4140035020.

Red has constant vacuum of over 15 in.Hg
Blue has no vacuum regardless of 4WD switching

A.D.D. Will not actuate with vacuum of up to 20 in. Hg applied to either side.

I still have to test the VSV solenoids with 12 volt jumper and ohmmeter, and am hoping they are good. (Why does every diagram I find show these on the passenger side, while mine are on the driver's side?)

I suspect the ADD may have failed. Can it be removed and repaired or only replaced?

Any suggestions or advice would be greatly appreciated!

blockhead

Going to pull the 3 switches on top of the TC and test those. Any suggestions on how to get those off, I can't get get a tool on them?

kaya4tmw

Many thanks to 99SC4Runner and everyone else who has contributed. In case it helps I will go over my exact symptoms. I first found this thread 3 years ago because my 4WD indicator lights were blinking and I knew I was stuck in 4wd by how it drove, this happened using the 2wd/4wd button on the side of the lever. After finding this I jumped the pins on the actuator and got it out immediately. Further investigating afterwards ended up with the lights only blinking when using the button. If I manually moved the lever using the locking differential, then the 4WD system would work like it should. Well being probably lazier than I should be, I was fine with that. So fast forward to a few weeks ago and using the lever did not work. Lights started blinking then as well. I again jumped the pins and got it out of 4WD. I live in Denver, CO. and they are probably in very high demand but I picked up the 4wd Sensor recommended part #84222-35070 for $76 and installed it today. It was easy but it took me a while to find it. I found the one right near the plug that I jumped but didn't notice the 2nd one right next to it..literally 2 inches away. Ended up I was looking about a foot too far to the left at two things that look almost the same but there are not plugs on them, just two pieces of wire on the end. (This is from below, drivers side with feet under the car and looking up) So once I saw the 2nd sensor 2 inches from the plug I jumped, it was a 15 minute job and the system works as it should using any method. I was even able to plug the electrical connector for the 2wd/4wd button in again. (Had that unplugged so somebody didn't accidentally hit it)
So again, many thanks to everyone and especially 99SC4Runner, you saved me $1200. FYI Dealer wanted to replace the actuator for $1300

speelyei

Thanks again to 99SC4RUNNER! Saved another!

We bought our In-Laws mint condition 99 Ltd Edition 4runner with all the electric bells and whistles, and 205000 mi. My wife's Dad took immaculate care of it, and had all the regular servicing and stuff done since they purchased it brand new. Then it came to us…

While 30 miles off road exploring old mines in AZ the M/M switch croaked and displayed all the same symptoms described in the original post. After just kind of sobbing and wishing it would go away I followed the bouncing ball, and VOILA! We're back on the road!

Now, if you should find yourself in some town with limited resources, like say… Kingman Arizona… and you go to NAPA, here's what you need:
They can't cross reference the Toyota #'s. I bought a 143-3024 "Reverse Light Switch".
It will work, but the electric connection socket needs to be sanded or filed down +- 3/32" to connect and lock securely, and you won't be able to get a short 27mm socket over the top, but an open end wrench will get you where need to go.

Thanks again so much for this thread and your initial work.

99SC4Runner

I still have Toyota # 84222-35110 new transfer switch that I bought from Toyota and never used. $55 shipped since I paid $55 for it. Just thought I'd let others know in case they need this sensor.