[bunzz]

Hey guys,

I've been having issues going into 4WD with my 2008 4runner sport v6. It started when I would just get an indefinitely blinking 4WD and diff lock light. I figured it would be the front actuator so I replaced that, and now I am getting just the blinking 4WD light and no diff lock light.

When putting the truck to "ON", i can hear the 4wd computer click twice, then the 4WD light starts blinking indefinitely. The truck is in 2WD. I've tried resetting the ECU, zero point calibration, tested the actuator to see if it was working, and it all seems to be working fine.

Any clues on what else to check for?

[TowMeOut]

This unfortunately is a common problem with the 4th gen. There are several threads on the subject but here's kind of a "summary"

Which ECU did you reset (engine or 4WD)? When I was troubleshooting and trying to re-time my t-case my calculations were off by a tooth and I ended up in what I believe was some kind of error mode. The 4WD ecu (on a panel under the glove box) goes into some kind of safe mode or error condition so you just get the flashing idiot lights. This is likely due to the shifting process timing out (jammed t-case or diff actuator). Until the condition is corrected and the ECU reset the light just keeps flashing. With the vehicle off I just unplugged the connection on the 4WD ecu and let it sit for a few minutes then plugged it back in. I had to repeat this process many times.

Generally, t-case actuator gets "stuck" from disuse. The grease inside hardens to the point that the little DC motors can't overcome the friction of moving it and the shift rods. So....an ounce of prevention is worth about $2K in repairs. I've got a timer on my phone NOW set to remind me to shift at least once a month. This is common to both the V6 and V8 but I think worse in the 6 since we have the additional front actuator to complicate the shifting process.

Since you've already replaced the front actuator (just like a friend of mine with the similar issue) that kind of solves that potential problem. Did you by chance try to move the locking collar back and forth by hand or shifting while the actuator was removed but pluged in?? Engaging the front diff seems to be the last step in the 2Hi-4Hi process after shifting the t-case.

The general consensus I believe is that you might get "lucky" if the temperature is high that the grease will soften up enough to get the t-case to shift. Some have had luck warming the assembly with a heat gun, loosening the bolts, tapping the actuator with a soft-faced, mallet, etc. All of this is while you have a buddy in the cab trying to shift the unit back and forth, hopefully getting it un-stuck.

Some have been successful but most either end up replacing the t-case actuator (about $500 on Amazon or over $1K at the dealer) or getting a used t-case with working actuator. Either way it stinks!!

If you're handy and do some searching around you can find the pin-out for the t-case connector, showing the actual motor connections (there are 2). If you can get a 12v power source and some small test leads or similar you can connect directly to the motor inputs and attempt to work them back and forth. If both operate then at least that somewhat narrows down the actuator as not the culprit. There is also a troubleshooting document floating around here somewhere that has the pin-out and test lead procedures for checking the actuator. Basically there are two small plastic gears with contacts that tell the ECU what position the shift rods are in. The "timing" can get screwed up where this little clockwork setup gets out of whack but since you haven't cracked open the t-case that's unlikely.

So....here's the list of problems to check:
t-case actuator
front diff actuator
reset 4WD ECU
Check dash switch
potential other electrical gremlins (harness damage, etc).

I was "successful" in replacing my actuator without cracking the t-case open but it took a lot more work. I wouldn't recommend it. Good luck....

[bunzz]

Originally Posted by TowMeOut

This unfortunately is a common problem with the 4th gen. There are several threads on the subject but here's kind of a "summary"

Which ECU did you reset (engine or 4WD)? When I was troubleshooting and trying to re-time my t-case my calculations were off by a tooth and I ended up in what I believe was some kind of error mode. The 4WD ecu (on a panel under the glove box) goes into some kind of safe mode or error condition so you just get the flashing idiot lights. This is likely due to the shifting process timing out (jammed t-case or diff actuator). Until the condition is corrected and the ECU reset the light just keeps flashing. With the vehicle off I just unplugged the connection on the 4WD ecu and let it sit for a few minutes then plugged it back in. I had to repeat this process many times.

Generally, t-case actuator gets "stuck" from disuse. The grease inside hardens to the point that the little DC motors can't overcome the friction of moving it and the shift rods. So....an ounce of prevention is worth about $2K in repairs. I've got a timer on my phone NOW set to remind me to shift at least once a month. This is common to both the V6 and V8 but I think worse in the 6 since we have the additional front actuator to complicate the shifting process.

Since you've already replaced the front actuator (just like a friend of mine with the similar issue) that kind of solves that potential problem. Did you by chance try to move the locking collar back and forth by hand or shifting while the actuator was removed but pluged in?? Engaging the front diff seems to be the last step in the 2Hi-4Hi process after shifting the t-case.

The general consensus I believe is that you might get "lucky" if the temperature is high that the grease will soften up enough to get the t-case to shift. Some have had luck warming the assembly with a heat gun, loosening the bolts, tapping the actuator with a soft-faced, mallet, etc. All of this is while you have a buddy in the cab trying to shift the unit back and forth, hopefully getting it un-stuck.

Some have been successful but most either end up replacing the t-case actuator (about $500 on Amazon or over $1K at the dealer) or getting a used t-case with working actuator. Either way it stinks!!

If you're handy and do some searching around you can find the pin-out for the t-case connector, showing the actual motor connections (there are 2). If you can get a 12v power source and some small test leads or similar you can connect directly to the motor inputs and attempt to work them back and forth. If both operate then at least that somewhat narrows down the actuator as not the culprit. There is also a troubleshooting document floating around here somewhere that has the pin-out and test lead procedures for checking the actuator. Basically there are two small plastic gears with contacts that tell the ECU what position the shift rods are in. The "timing" can get screwed up where this little clockwork setup gets out of whack but since you haven't cracked open the t-case that's unlikely.

So....here's the list of problems to check:
t-case actuator
front diff actuator
reset 4WD ECU
Check dash switch
potential other electrical gremlins (harness damage, etc).

I was "successful" in replacing my actuator without cracking the t-case open but it took a lot more work. I wouldn't recommend it. Good luck....

This was extremely useful and makes sense. (We should have a 4WD diagnostic thread to consolidate all the issues).

I actually just took the front actuator out again just to double check everything (an annoying pain but worth possibly getting 4WD back). The front collar moves back and forth rather easily. After installation I rotated the front driveshaft to check if it spun loosely. Then I applied some voltage to the actuator to set it into 4wd, and I heard the motor move and also the collar clicking over the gear. When I tried to spin the front driveshaft, i was not able to move it, so the front is properly engaging.

It definitely must be some type of error failure. The truck is unresponsive to the control switch.

To give some background, I drove through somewhat deep water puddles on a trail a month ago, I'd say they were probably around 1-2 feet high and started having the beginning issues I stated in my original post. When I went to check the front actuator the breather nipple was super glued onto the assembly and the hose was hanging loosely. Long story short, when I removed the old actuator and pointed the nipple down, brown water started pouring out of it.

Anywho, I have the battery out and the ECU unplugged currently. I've seen the threads on carefully removing the actuator, so I guess I will weigh out my options. I definitely don't want to take out the transfer case in my garage.

Thanks again!

[Rbates1]

I recently bought two 4th gens, first was my wifes 06 limited 4.0. I did my research beforehand and new to check the 4x4 ranges. Well both vehicles were 1 owners and hers had the dreaded no 4lo and just beep beep beep all the time. I joined the forum here and read up on it, and was suggested before any major repairs that I just keep working the actuator every couple of days especially with the summer temps getting up near 100 here in TN. Well the day that I had her front windows tinted i backed into the drivewat and thought what the hell, ill give it a shot. Well it popped right in to my amazement and then i continued to work it through all modes for a good 30 minutes. Works like a charm now. My guess is the PO never used it and it got gummed up from disuse as mentioned above. Keep trying it everyday when you get a chance. You never know when it might finally break the chains of time lol.

[CrimsonCountry]

Originally Posted by Rbates1

I recently bought two 4th gens, first was my wifes 06 limited 4.0. I did my research beforehand and new to check the 4x4 ranges. Well both vehicles were 1 owners and hers had the dreaded no 4lo and just beep beep beep all the time. I joined the forum here and read up on it, and was suggested before any major repairs that I just keep working the actuator every couple of days especially with the summer temps getting up near 100 here in TN. Well the day that I had her front windows tinted i backed into the drivewat and thought what the hell, ill give it a shot. Well it popped right in to my amazement and then i continued to work it through all modes for a good 30 minutes. Works like a charm now. My guess is the PO never used it and it got gummed up from disuse as mentioned above. Keep trying it everyday when you get a chance. You never know when it might finally break the chains of time lol.

I would echo using the heat to your advantage. I actually got my 4lo to engage for the 1st time since buying it in 2011 after several days of 100+ degree heat. So pumped! I've engaged it 30 times or so since then just to keep it moving but will now set a monthly reminder for myself. Full disclosure, 4hi has always worked. Good luck!

Sent from my couch

[duffdog]

Originally Posted by bunzz

This was extremely useful and makes sense. (We should have a 4WD diagnostic thread to consolidate all the issues).

I actually just took the front actuator out again just to double check everything (an annoying pain but worth possibly getting 4WD back). The front collar moves back and forth rather easily. After installation I rotated the front driveshaft to check if it spun loosely. Then I applied some voltage to the actuator to set it into 4wd, and I heard the motor move and also the collar clicking over the gear. When I tried to spin the front driveshaft, i was not able to move it, so the front is properly engaging.

It definitely must be some type of error failure. The truck is unresponsive to the control switch.

To give some background, I drove through somewhat deep water puddles on a trail a month ago, I'd say they were probably around 1-2 feet high and started having the beginning issues I stated in my original post. When I went to check the front actuator the breather nipple was super glued onto the assembly and the hose was hanging loosely. Long story short, when I removed the old actuator and pointed the nipple down, brown water started pouring out of it.

Anywho, I have the battery out and the ECU unplugged currently. I've seen the threads on carefully removing the actuator, so I guess I will weigh out my options. I definitely don't want to take out the transfer case in my garage.

Thanks again!

I bet you that the components inside the actuator are all rusted. I did the same thing, drive through water and then 4wd does not work. If you feel like replacing the rusted motors in the actuator case I wrote a thread about how to time them so that the computer will recognize the different modes. Just do a search for that. I had to replace the motor and retime all the gears, but now it works like new.

[bunzz]

Just want to update this in case anyone else is having an issue where ONLY the green 4wd indicator is flashing, and their trucks are unresponsive to the switch:

It's the front actuator.

The truck checks if it can communicate with the front and if it gets no response back, your 4WD ECU essentially goes into limp mode and will not do anything. I ordered an actuator from an ebay reseller and it turns out the part was a dud. I took the truck to the dealer, they put in a known working front actuator and the truck was back to normal.

I'm told it could have been from trying to manually power the actuator, which I did do before I installed it, this could have been my fault, but I hear others have done this with no issues. Either way, I'm able to return the bad part and now I have my 4Hi and 4lo functional. Yay!

[va79ta]

I just found this thread. I have a similar problem. The vehicle won't shift into 4x4 at all. I followed some steps others have suggested: cycle the selector while it's hot out, thump on the transfer case actuator with a mallet, loosened the bolts and wiggled the actuator... While I was under there I found the hose one the actuator broken. I fixed that and nothing. I removed the metal access panel on the actuator and found the little blue button. I figured it might be a reset button and pressed it. Now the green 4x4 light remains on, and the transfer case lock light blinks, when the knob is in 4hi. I may go in and unplug the ECU and see if that clears out the lights.

I went from the car not looking like anything is wrong, to lights flashing all the time. Doesn't bode well for trying to sell it in the future

[Bigcee]

My 09 SR5 blinks the 4x4 and Amber icons when turning the knob to 4Hi or 4Lo. In 2WD, I don't have blinking lights. Is my issues the same as OP's or am I mistaken?

[Pbuscemi]

Hey guys,

I have a 2005 4Runner V6 4WD. I use the 4WD pretty regularly, but 4lo has never worked. I am sure the actuator is frozen, but that's not why I am here.

We have had a crazy 2 weeks of winter here, and it's currently -4 outside. So anyway, I was driving earlier and went to disengage 4Hi on the fly to 2Hi. When I did this I heard a loud clunking or knocking sound (NOT a grinding sound) that stopped after about 10 seconds, and then my center lock and 4WD light flashed for awhile, and never disengaged. I ended up needing to pull over, put the level back to 4WD, put the car in park, N, R, then D and it disengaged. Anyone else having this problem?