99SC4Runner

I'd check the 4wd system sensors and verify that they are all still plugged in. The dealership might have unplugged one of them (possibly the front diff sensor) when R & R of the motor.

Keep us posted.

Doug

1990yota-pickup

double zero did you get your money back or what...?

kkcolt4

I am having the same issue with a 2002 Sequoia limited 4x4, can I get you to send me pics also please. thanks.

99SC4Runner

You can access them at my photobucket link here;

http://gs157.photobucket.com/groups/t42/JEP5U3X44E/

Dianna

I have a 2001 4Runner that has the 4WD dash lights flashing. I was having this issue for a couple weeks where it would take a few minutes to engage but now it's been a week and it's in 2WD with the lights flashing. I'm glad I found this thread but I'm wondering if my 4runner is different since in 2001 "an electric motor type actuator has been adopted for the A.D.D. (Automatic Disconnecting Differential) actuator."

I should also mention that I currently have a CEL and code PO446, is it safe to assume that because the problem is in the EVAP system this has nothing to do with my 4WD?

99SC4Runner

The transfer case actuator motor is different, but the design is probably close to the 99 4Runner. I haven't looked at the 2001 style 4Runners to understand them better.

I'm sure you'll still have the transfer switches (sensors) in the front diff and the t-case, so I would start by checking them and verifying that they are good or not.

glenyoshida

I took a look at the FSM for the 99 and the 2001 and the actuator on the 1999 has two vacuum hoses where as the 2001 only has one vacuum line.

99SC4Runner

I'd check to make sure that the single vacuum line is still connected and not worn through. Then I'd start testing the transfer switches on the front diff and the t-case for starters. It might just be a bad transfer switch (sensor).

ender81

I have been following this thread for the last two weeks. My 4WD was taking longer and longer to shift.

On FEB 26 I was driving on the highway in 2WD. All of the sudden, the 4WD lights started flashing on the dash intermittently. They would flash for a few seconds and then go off- then start 30 seconds later or so and last for 10-45 seconds. Eventually they stayed on all the way home.

Having no experience working on vehicles, I took the truck into the dealer. I explained in detail the intermittent flashing. They took a look the next day and gave me a call. They said they they know the front actuator is locking the front axle, but that they suspect the transfer case actuator and that the repair would be ~$1500. Try told me that the T-Case actuator was getting power but was not locking/engaging the shafts together.

After digesting the news I did some more reading here. I called the next day and ask the service rep to check the front differential locking switch and the other switches associated with the t-case prior to replacing the motor. The service rep did not seem to want to do this- he even game me the line that if it didn't help, I was basically just wasting a couple hundred bucks. Frustrated by the dealer and encouraged by this forum, I decided to pick up my truck and test the sensors myself.

I have successfully pulled and tested the two switches on the rear of the t-case- both good. I have not been able to pull the two top switches- but I have disconnected them and get an open reading on both.

After picking up my truck I drove it to work the next morning. I made sure my truck was in 2WD by driving forward and backward until I heard a slight click and the lights on the dash went out.

15 miles into my 18 miles drive, while cruising on the highway at about 65mph the lights came on an there was a grinding type noise in the front of the the truck. I quickly pulled over and place the truck into neutral. Lights still flashing, I checked to make sure the 4WD button was depressed. I shifted the 4WD to Neutral, then 4L then back to Neutral and 4H a few times. Lights still flashing, I tried to drive- no issues. I made it to work without further incident.

Thinking about this at work and reading the forums, I began to suspect my 4WD computer. Reason: My 4WD should not be able to engage itself. Even if my t-case actuator was bad as diagnosed by the dealer, my 4wd should not be able to turn itself on. Something has to tell the system to do something.

When I tried to head home at the end of the day I had the same problem- lights randomly flashed and started a grinding noise in the front of the truck. My solution was to disconnect the 4WD computer. Result: A very quiet and uneventful 18 mile drive home. As soon as I plugged it back in, the 4WD lights started flashing.

Vacuum lines look fine.

So I am pretty sure that it is the 4WD Computer board, part number 89533-35170. I can order a used one for $100-$150 or a new one for $240 online. Electrical parts are not returnable.

What do you guys think? Faulty 4wd computer?

ender81

Any thoughts guys? I really don't want to take this back to the dealer. I have a really hard time believing that the problem is the t-case actuator at this point. Looking for some input from the forum before I pull the trigger on a new board.

Thanks.

Tonyo

I have 2001 FYI guys on the 01 these are not vacuum lines to front actuator and rear these are only breathers lines why i do not know

I tried replacing the sensor rear transfer case the front one 8422212010 it didn’t help I pulled front actuator there is no sensor up there I think my next plan is to remove rear sensor and test does anyone know what resistance I should have

Tonyo

I have done plenty auto and 4wd work but not with the electronic stuff this is all confusing to me all this referring to sensors which really is just a switch right?

I don’t have any sensor on front diff only and actuator with 6 pin harness I don’t know what is supposed to be powered there but one of them has 11 volts

On other hand I have 2 sensors/switches on top Tcase and 2 at rear of Tcase mounted in actuator housing I replaced part# 8422212010 that did not help.
I pulled the other sensor tested with ohm meter it seemed to work ok I don’t what resistance specs its suppose to but sis seem work like switch.

Since I have front actuator pulled what I did next was disconnect each sensor one at a time and jumped it and watched the actuator and it didn’t seem to move at all I am thinking maybe my front actuator is bad
I have not been using 4wd much lately and I know that’s not good they can freeze up but I was in death valley at time using 4wd day before switching on and off just fine so that is weird.

One other thing confuses me is this center locker when it was stuck in 4wd if I tried engaging center locker it never went in all way the lights always kept blinking I would think it should have worked.

ender81

I am having the same issues brother. I spent about 3 hours today trouble shooting. I checked the sensors- yes they are basically switches. After you remove them, the test is to press them down all the way and then check for continuity- when pressed all the way in you close the switch.

My 4WD lights flash no matter what I do at this point. I can eventually get the truck out of 4WD by driving forward and backward. After that, the lights randomly come back on. Also- they some times flicker very erratically. I pulled the 4WD computer located in the left kick panel of the drivers side- nothing smelled burned.

Tried trouble shooting the ECU as directed in the FSM- Checking between terminal 4(2-4H selection switch) and Terminal 25 (GRD) everything worked as described in the FSM. I had issues when checking between terminal 6 (4WD) and 25(GRD). According to the Trouble shooting manual I should have 10-14v with 4WD off, and less than 2v after pressing the 2-4WD selector switch.

All of this, added to the way the light flickers steady for a while and then fizzles in and out erratically leads me back to the 4WD board. I am going to order a used one and try to swap it out.

If anyone has any better ideas, please speak up. Tonyo and I could use some help.

Tonyo

i am not sure what to next i would sure like to have copy of fsm you used to test the ECU or if you have one to test the front actuator when its off and unpluged

Tonyo

based on my tests and friend i know who owns shop i am going to buy front actuator tomorrow i heard its not likely for ECU and of all the posts i read many have tried changing and i dont think it was ever the fix

i will keep posted this weekend after installed

Tonyo

Well i never done this before but i am now.

putting on parts with out being 100% sure the part is bad

i installed front actuator and still no change everything to me pointed to it but i was wrong.

im stumped now i am thinking to take to local dealer and thought of that making me sick i never have taking car to dealer before other then a recall repair

ender81

Well my 4wd computer arrived. Did not solve the problem. However, when I installed it, the board started clicking like crazy. I could hear something under the truck trying to engage. When I got down to listen I could hear the ADD actuator clicking and whining intermittently.

When I shift into 4L, I can see the front drive shaft turning, and when I test the 4L switch on the t case it reads closed- so I know that the T-case actuator is good. Right?

I am pretty sure the front differential isn't locking. When I tried to drive straight over a curb in 4L, the drive shaft spins, but the front wheels don't- back wheels end up losing traction.

After shifting back to 2H and driving the truck forward and backwards to get it completely back to 2WD, I drove the truck around my neighborhood. 1-2 minutes into the drive, my 4WD light lit up solid, with the center differential showing locked. WTF is going on???? Crazy short in the wiring?

Still getting the random flicker sometimes with the truck in park, neutral and drive. Disconnecting the ADD harness did not change the flickering situation.

Thoughts? Time to go back to the dealer?

Tonyo

I took my truck to shop near me that was recommended to me and they were not able to find because I really didn’t like what they were checking anyway there was no charge.
So crap I did it I took to local Hayward to dealer and waiting there answer I am thinking they are leaning towards rear actuator ouch I am afraid hear cost of that.
If need to take out tans and Tcase I don’t any shop in area I would trust to do that will keep you posted
ender81 so what did you do next

Tonyo

OMG they called back they think its rear actuator what a surprise they need another tech to confirm tomorrow but heres the shock they charge 2900 to change that there is no in hell i will pay that much i used to do tanny work how hard can it be to pull tcase apart right?

ender81

I dropped my 4Runner off at the dealer on Sunday. I am going to let them try the T-case actuator at this point. I ran out of ideas. I am really hoping they get in there again and tell me it is either the front ADD or the t-case itself. The t-case is covered under warranty so that would rock.

We'll see. Good luck man. Looks like we both have fairly expensive repairs in our futures.

I'll keep everyone posted.