spaber05

So I went wheelin today, and found out that I can't get her into 4WD, hi OR lo. The little 4WD display on the dash (u know with the green lights for tires and orange for the center diff) is flashing at me, and I can't figure it out. One of my buddies who knows what he's doing took a look, and the front driveshaft IS connected and moves the car when you twist it, but I'm still not in 4WD. I tried, reversing, neutral, drive in just about every available combo of LO, HI, 2WD, 4WD, u name it. I pulled the fuse, disconnected the battery to reset everything, but Im still getting the flashing display and still in 2WD. Funny thing is, that when I tried putting it in 4LO, for a little bit, it was in LO (I could tell by the slight whining of LO and the gearing), but then as soon as I tried climbing a little hill, it was only my rear tires spinning. She seems to drive FINE as if nothing was wrong. Does ANYBODY know whats going on? It was said that it could be the actuator motor, but we were just making educated guesses. Please, I'm going to the dealer but I'd like to know what I could be getting myself into! Thanks in advance to anyone that can help.

Pilottech

If you pull the plug on the actuator and use 12volt source to see if you have a bad actuator.

With the plug to the actuator in your hand and the lock of the plug in the up position the pins are #'d backwards 321 on the top row and 654 on the bottom. With + on pin 3 and - on pin 2 the DC motor will drive the actuator into 4WD and then +2 and -3 it will go back to 2HI. This will tell you if the actuator motor works or not. If the motor works then you can look other places.

I do not have a plan yet for troubleshooting the Computer or the wiring. Just know how to T/S the actuator on the Multi-Mode Solenoids at this time. Hope to help more later.

spaber05

thanks, I'll give that a try tomorrow

iholla

Had that happen to my 99 and it was the actuator that was bad.

spaber05

Ok, back to square one...found out the actuator is fine after we performed the test as suggested by pilottech. Oddly enough, the connector wasn't 2 rows of 3 pins, but one long single row of 6 pins. I assume you were suggesting testing the 4WD actuator in the middle of the truck not the one on the front axle? (I know thats got newbie written all over it) Thats what we are thinking next, or that its some sensor up on the front axle gone haywire.

Pilottech

You are correct, I was not specific, and the test was for the Xfer case actuator. This means that the actuator works. The front drive shaft actuator is vacuum controlled on the 99 4Runner.

Congratulations on getting back to 2WD. Don't need the extra wear and tear when not needed.

The rest of this statement may not be required; I have completed this just to figure the system out.

The logic is next to T/S. Remember I am learning as I go as well.
My next step was looking at the actuator location switches. These are above the Transfer Case Actuator. There are two large dip switches with plugs on-top.

Disconnect the plugs (the plugs are different, to prevent wrong hook-up). I then used a large adjustable wrench (did not take the time for the exact size wrench) to get the switches out (now this is where you need to pay attention to not mixing up the location of each switch, I believe the plug with three slots is the aft switch). Yes, this may be a little tight, watch the knuckles, not as bad as TVV on the engine. The test is to use a meter to determine continuity. Remove the switches, switch not depress-open continuity, switch depressed- close continuity.

Next use a vacuum pump to determine if the ADD (Automatic Disengaging Differential) system is leaking. This hose comes off the engine manifold just behind the radiator cap (small hose) and then goes to a junction (one to a vacuum reservoir and the others to the ADD solenoids. I used a small hand held pump with a gauge to determine if I had a leak. The aft solenoid exit hose the front differential is to engage the front differential to the front drive shaft. The forward exit hose of the solenoid to the differential disconnects the front differential.
Swap the Vacuum Lines to the ADD on top of the left front wheel well. The check is to swap the vacuum line when not in 4WD with the vehicle at idle. When the lines are swapped and vehicle is idling then front drive shaft is locked to the front differential.

The rest is to check the wiring.

I have ordered the 4WD Control Computer to see if this will help, will keep all advised to the outcome. This is located just under the left kick panel (next to the left foot of the driver side). The new part here in Glen Allen, VA is $280 and a few other places tried to charge me $350. I have found the part from an online salvage yard for $75. My Computer Module Part # 89533-35150.

Hope this help anyone trying to T/S the problem.

Remember, keep the dirty side down.

MTL_4runner

If the light is blinking, then you are not yet fully locked in 4WD. When it locks in, it will go solid.

It sometimes is a bit finicky to go into and out of 4WD when you are not moving. I always do it when I'm rolling slightly. For now, though, start the truck, make sure your transfer case lever is fully in the "H" position, and make sure the 4WD button on your transfer case lever is not pressed in. If the light continues blinking, put your foot on the brake, shift the tranny to drive, then reverse, then drive, then reverse. It should eventually unlock for you. Driving in reverse and tapping the brakes can often free up a stuck ADD system.

Here's your possibilities (if the above doesn't work) right out of the FSM:

1. 4WD fuse
2. Wire harness
3. Vehicle speed sensor
4. 4WD position switch
5. 4WD indicator light
6. Actuator assembly
7. A.D.D. control system
8. 4WD control ECU
9. Transfer assembly

It might help you to also have a look at this article:
http://toyota.off-road.com/toyota/ar....jsp?id=399612

spaber05

good stuff pilottech, I was never in 4WD fully, as the blinking lights indicated, or else I would have a hell of a lot less mud on rear half of the truck! MTL-believe me, we gave it plenty of time and movement to get into 4WD, reverse, forward, neutral, hi, lo, we did it and still it flashed and still 2WD. We checked the plugs on top of the actuator and they looked good, but I spose we need to take them out completely. Other than the obvious bolts to get the actuator off, do you just pull it off the driveshaft? We had all the bolts out and it came an inch or so, exposing more of the shaft, but didn't want to come off completely. In doing so, we disengaged the front driveshaft, which makes sense, but it didn't want to come off. Sounds like we need to check out the front next. I'll keep you posted if we have some sort of revalation haha.

MTL_4runner

I'd bet money it's your front actuator causing you all the grief.

spaber05

yeah thats what I'm checking later, called toyota they said they've never had issues with the xfer case actuator. I'll keep you guys updated

iholla

I probably should have said it WAS my Front Actuator that was bad in mine!!

Pilottech

I have not pulled the actuator, I did pull the guts out of the actuator.

The switches that I was suggesting to check are the ones at the plugs onto of the actuator. Did not want you to pull the actuator off the transfer case. This will require taking the actuator apart. I have done this once now but don't suggest it. The timing of the rotor is a big deal. I was able to blue print from another one. Now that I have seen the part apart, I don't think this is your problem since your actuator works.

Just wanted to make sure you were not going to pull the actuator.

spaber05

No I (as you put it) pulled the guts out without actually pulling the whole assembly off. This was the transfer case one which turned out to be working fine, NOT the front. I took a real quick look at my FRONT actuator, it looked good with no obvious dents or anything, pulled off the plug, sprayed some compressed air in the connections, plugged it back in and nothing changed. That was all I had time for, that and the screwes to take it apart started stripping and I didn't want to start anything I couldn't finish up quickly. Tomorrow's mission is to check the front.

MTL_4runner

Pilottech, your system and spaber05's are quite different so keep that in mind when your comparing notes so to speak. The 96-00 are very similar in function to one another, but in 01-02 they changed fairly significantly, adding the one touch high system (previously only available on LTD models), center dif lock and electric motors for all the actuators just to name a few things.

Pilottech

MLT 4Runner, nice article, I will go look for the relay in this article. I will give feedback on what I find.

Not sure how different the two vehicles are?

The 99 4Runner Limited seems to more like the later years. I am interested to hear if the front diff is vacuum or electric?

spaber05

well, its not the front actuator either, found that out about a half hr ago. My next guess is a connection to the actuator because its just not getting power. I'm thinking dealership is the way to go at this point, I will just tell em to stay away from the actuators and focus on the connections and hope they listen to save me some $$

spaber05

I lied, it was the front actuator haha, it bench tested fine but the new one made everything better. 4wd shifts are almost instantaneous now, hell of a lot faster than before. Thanks for everyone's input and I hope this saves someone in the future. Now time to go test it out and make sure everything works haha.

Pilottech

Did you change the actuator or did you let the shop? Was the cost bad?

Pilottech

It is great to hear you had a good fix. Thanks back at you, all then information has and will help us all. It is always nice to have someone post the final fix. Hope it was not too expensive?

MTL_4runner

Who called that one!