Just posting to thanks for all the excellent info everyone has shared in this thread. My problem was a little different but the info here helped me sort through the problem and finally get my 4WD working flawlessly.

I have a 2001 Sport that started (about 9 months ago) having intermittent problems going into 4WD. At first it would go into 4WD (you could hear the actuators lock in and it was obvious that it was locked in) but the green and orange lights would keep flashing. Cycling it in and out a few times would eventually get it where the lights would work correctly.

A few months later it would not go into 4WD but the lights would start flashing. Fortunately I found a way to get it to cycle in during a couple of needed times by climbing underneath and disconnecting the 6 pin connector on the xfer case actuator, pressing the 4WD button and then reconnecting the 6 pin. At this point I also removed all of the sensor switches and tested them, finding none were having an issue. I also noted that the breather tube on the xfer case actuator was cracked and just barely staying in place.

About a month ago I started having issues where it would get stuck in 4WD and not come out and other times where it would not want to go into 4WD at all. I again pulled and tested all of the switches, re-seated all connectors, etc... and could not find anything wrong. So I decided to pull the black cover/drive motor off the xfer case actuator to see if there was an issue with the contacts inside it. As I pull it off, water starts coming out of the actuator assemble (perhaps an ounce at most). The motor spiral gear, gear that runs the actuator into place and the contact race tracks in the cover are all covered in a pasty, greasy rust.

So I cleaned out the water, rust and old grease from everything and re-greased it all. Put it all back together and boom, everything started working like new.

Obviously not the same issue as the original post, but I think this thread is the most complete collection of info related to these types of issued and hope my input will help somebody else.

Just a couple quick notes on pulling the motor cover off the actuator:

1. Loosen the 10mm bolts but keep them threaded in a few turns until you work the cover off. Mine was a little tight and I did not want to have stuff flying around if it came flying out of my hand.

2. After you get it off - leave the main drive gear in place. I am not sure if you can pull it off easily, but I had read that some folks had issues re-timing it after taking it off.

3. I took the drive motor cover off and pulled the spline shaft out of the cover. If you do this be very careful pulling it out as there are springs and small ball bearings on the ends of the shaft that can and will go flying. In retrospect, I did not need to pull it apart. Re-assembly of the motor is challenging as there are little spring-loaded motor contacts that are a pain.

 

SO glad I just found this...I'll be trying it very soon because that blinking light is haunting me. Just a quick question...I have the '99 Limited and when I go into any of the 4x4 options everything works just fine. I can never get out of 4WD with the vehicle running. However, if I shut the vehicle off, it does go back into 2WD. Has that been happening to anyone else? I just want to try and make sure that your solution will also solve my problem. Though I'm sure it will because this seems to be a VERY common problem for the 99's.

 

Just test each switch/sensor until you find one that doesn't work, and that will most likely be your culprit.

 

Looks as though I'm back in the unfortunate position dealing w/ the blinking lights again (posted here back in 2012 when I discovered my external actuator motor had failed.)

Was in 2wd this time when I left home Sat. Got to spot where I needed to engage 4wd before continuing into the trail, pushed the button on the shifter and just got blinking lights. Tried inching forward and backwards a few times to engage 4wd, but no dice. Didn't have any tools on me, so ended up driving back home in 2wd...with the 4wd lights blinking.

On the positive side, at least I'm not stuck IN 4wd...but these blinking lights are driving me nuts. Not being able to engage 4wd is a buzz kill!

 

Joined here just to say thank you for this thread. And this post as it helped me fix my wife's 01 4runner. Same thing, vent feel off actuator and water got inside. Simple repair that I thought was going to be much worse. Here are a few pics from what i found.

 

To you and wlaurent- what did you guys use to clean out the rust and old grease?

My 4wd lights quit blinking 2 days ago, so that's a plus. I'm thinking my problem may be again at the actuator motor as before. I hope to pull my cover this weekend and see what's up.

 

Pocket knife, b12 carb cleaner, and some used 80 grit sand paper. And a hit of compressed air I think.

 

Just to report, 4wd is back working again...although, I'm not sure why. Took the cover off the actuator motor and inspected it. Everything was as clean and greased as the day I installed it 3yrs ago after the original failed. Reinstalled the cover and tried switching in & out of 4HI. Worked perfect each time.

 

This thread has a TON of great info on a problem I've been having also. I have a 99 4Runner LTD. My question is:
Does anyone know if you can engage the 4wheel drive without pressing the 4wd button on the T-case lever? If I pull the stick down into the 4H setting will this work?

 

The '99 and '00 limited has:

1st Position: H2 - Two Wheel Drive
1st Position + Button pushed: H4 center diff Unlocked - AWD
2nd Position: H4L - 4 wheel drive with center diff locked
Neutral
3rd Position: L4L - 4 wheel drive low with center diff locked

Yes, you can go into H4L without pushing the button and engaging H4 first.

The dash indicator will reflect what the 4wd system is doing as well

Off - 2wd
4 green tires no yellow = H4
4 green tires with yellow center = H4L

 

Thanks so much for putting together this thread, Doug!

I'm trying to diagnose my problem and I've managed to read through all 20 pages of the thread to figure out what might be wrong.

I have a 96 Toyota Hilux imported from Japan. I took it out on the weekend and after returned to the pavement, the 4wd would not disengage. The 4wd lights including the centre orange light flashes when I try to disengage the electronic switch.

I've checked the position sensor on the front diff many times and also the two on the back of transfer case. All are normally open and snow continuity when pressed. I've hooked up 12V to the transfer case actuator to engage and disengage the 4wd successfully. It seems to work fine but I have not pulled the cover to inspect it.

I'm not sure where to go from here. I've heard you talk about checking the vacuum hoses but I'm not sure where to check those. Is there anything else anyone can think of to try? I'm pretty stumped at this point.

Thanks!

 

Thanks for the insight Cmayer. I'll have to try this out as the AWD Button makes me a little nervous these days since it hasn't seemed to want to enagage/disengage at times which causes the front wheels to bind up. Im about to replace the front diff sensor as well as the center diff lock sensor in hopes that my system will work properly again.

 

Guys I'm so sorry to resurrect an old post that has been gone over so many times but I assure you I have spent days reading every post possible related to the blinking 4wd. I have tested every switch and the actuator on my 2000 4runner Limited with perfect results every time. The 4wd tends to work in all modes about 95% of the time. When it acts up the conditions are as follows... Usually in 2wd, mornings most often, when the truck is wet or just at random the lights will blink. I cannot find any damaged wires or connections anywhere, everything is clean and tight. I am pulling my hair out with this. For example, I want offroading yesterday through every possible terrain including mud and the 4wd system as a whole worked flawlessly. I come home, spray all the mud offoff... 4wd light starts blinking. Leave the truck sit for several hours the come check on it again. Still blinking. Disconnected every connection for the 4wd system and still blinked. Put it all back together... Still blinked. Took it out for a test drive. Within a couple minutes of driving at 70mph the lights stopped blinking on their own and everything is again working perfectly... Please help because I have no idea what else to do. Thanks guys.

 

Well, I see three possibilities.

1) Something is effed up in the cluster (unlikely but possible)
2) 4wd ECU is effed up, still unlikely, but less so than#1
3) 4wd ECU is receiving a rogue signal telling it H2 is not the case after it has been called.

First, you need to be in H2 when light is blinking. Then, unplug 4wd ECU. If still blinking, you have Case 1. If not, probe for rogue signal. Apply voltmeter to the following pins of 4wd connector: 4,6,8, 9, 18,19, 22. All should report 0.5V or less. If they do, and light is still blinking when you plug connector back in, you have Case #2. If you have a voltage over 0.5V on one of those pins, then it's Case #3. Trace the corresponding circuit for that pin to find source of rogue signal. Diagram attached showing circuit for each pin and includes pin-out for 4wd ECU plug F7 on last page. It's for '99 but '99 and 2000 are identical.

Easy Peasey. .......................................(I'm kidding)

P.S. If you have rear e-locker, we need to check a few more pins. Let me know.

 

Durk you sir are the man. I will do exactly as stated when it happens again. As to your question to whether it has the rear locker or not... It does indeed. Stick with me close on this one buddy because I think you may be my only shot to finding this ghost.

 

Ok. Add pins 5 and 7 to the list. I'm in here every day. I'll be watching the thread. I hate intermittent fails, but with a little luck we can nail it down.

Sorry...and you also need to confirm ground or open on each pin. So first, put black probe on a good ground and check for voltage. Then put red probe to a live 12V+ source and check each pin again. I was in a hurry on the first post and just went by the FSM service hints.

 

Well it hasn't acted up again as of yet so Im still keeping a close eye on it. When it does I will make sure to check the voltage at all the pins you listed Durk. Thanks again buddy.

 

Ok, so we had a super hard rain yesterday that was actually flooding the freeway while I was driving. As soon as we hit a huge deep puddle in the road, the 4wd light began to flash again. Unfortunately it stopped before I could get it home to test it while it was acting up. At this point I think I'm going to have to completely soak down the undercarriage and engine compartment to create the condition and run your tests. My question is this, I need to leave the 4wd computer connected to that harness and back-probe the connector, correct? Common sense would say yes but I wasn't sure if the switches and such received their power from another source or not.

 

No, unplug the connector. You are checking to see if there is rogue voltage coming in from somewhere else or whether those switches are closed and giving a path to ground or if they are open.

 

Ok I'm going in for the kill to test it all out today. Fingers crossed that we find it!