tokyo_tad

I'm a lurker with a 2000 4runner limited 4WD multi-mode w/ rear locker (ie push button 4WD and J-lever for 2H/4H unlocked/4Hi locked/4Lo Locked). I searched high and low and seem to have a very weird issue.

Typically usually only drive in 2H except when it rains here in California, will engage push button 4WD 4H (center diff unlocked) to make sure I use my 4WD system. I only do 4H locked when I go up to Tahoe.

Here's the weird part. I started my truck yesterday and out of the blue, the gauge cluster/dash shows 4WD is enabled (NOT blinking, shows solid all four green tires) and push button is DISABLED (ie should be in 2WD). I try to push the button a few times. Nothing changes. Weird thing is, its NOT blinking like all the other threads I searched. Its just a solid green four wheels / ie 4WD.

I crawled under my truck and sure enough, I can't spin the front driveshaft (ie confirmed its in 4WD just as dash indicator says). I checked the front diff actuator sensor and did continuity test. Shows continuity ONLY when end is pushed in. Just for good measure, I test the 2 sensors by the transfer case actuator and they check out.

Since I'm in 4WD (confirmed via driveshaft and dash lights), I shifted into 4H locked and it goes in (orange diff lights up) and 4L locked works. Can go back into 2H/4H unlocked no issues (well lights blink and then get unlocks). I know what center diff lock feels like so def can lock and unlock center diff.

Now the weird part is, with the button not enabled, why wouldn't the system try to kick me out of 4WD (ie flashing lights on dash)?

I have read up on the VSV solenoids but seems like thats culprit for folks that can't get into 4WD. Again, system doesn't seem to try to get out of 4WD since I don't see any flashing green lights to try to dis-engage the 4WD. My guess is 4WD computer is telling it to go into 4WD open center but why???

Anyone have any suggestions??

fierohink

You might have a faulty multi-mode switch. Or the actuator traces could be corroded at the far ends of their range so it moves enough to trigger the position switches, but not enough to fully disengage 4wd.

tokyo_tad

I checked the multi-mode switch today with a multi-meter. Switch is working. Also probe the other end of connector and it reads 12V (ie multi-mode switch would complete the 12V circuit).

I probed the voltages on the VSV and it seems I'm getting ~12V on both blue and brown VSVs. Is this normal? Based on all the searches, some people say they have only 1 that is hot while others say both are showing power.

fierohink

I too thought my VSVs were my issue. They don’t react the way they are supposed to if a position switch is faulty. So even though my VSVs weren’t showing correct voltage or vacuum the first time I checked them, when I fixed my position switch they responded with proper voltage and vacuum outputs again.

tokyo_tad

I'm at a loss for what's going on with this now.

I jumped the transfer case actuator with a 12V source for pins 2 and 3 and electric motor for actuator on transfer case does work. With the car turned off, when I use the 12V to actuate 2WD on transfer case it slips in and when I power/start the car, my 4runner goes back into 4WD. For some reason, my 4runner believes it should be in 4WD and stays in 4WD. I checked the voltages of the 4wd multi-mode button and it is working. I also checked what the ECU sees on pin 4 from the multi-mode button and it sees ~10V (ie 2WD). I'm at a loss on what to check next here. I'm usually pretty handy and debug both mechical/electrical issues but this one has me stumped.

fierohink

Are you checking the position switches at the front diff and transfer case? There should be 5 total position switches, 1 on the front diff, 2 low in the drivers side of the transfer case, and 2 high on the passenger side of the transfer case.

also did you take the round cover off the actuator to see the condition of the contact traces that the actuator follows? If you read thru my build thread, I have pictures of the corrosion that was inside my actuator housing. Once I cleaned it up, everything worked as intended.

The multi-mode 4wd System on These vehicles have a lot of parts and controls that need to be in sync. When they are, the capability is far superior to its contemporaries. When a piece isn’t working, it makes things look unnecessarily complicated.

tokyo_tad

I checked all my solenoid switches and they all were good.

I ended up probing each of the pins on the 4WD ECU to help determine what the ECU see's from the car's sensors. After checking out all the switches/sensors were ok, I thought maybe the ECU is bad since it is telling the actuator to switch into 4WD even though all inputs into the ECU say 2WD. I swapped out to a new 4WD ECU and this cleared up the issue. My 4runner is now in 2WD when it should be and switches in and out of 4WD on demand as it should.

I thought other folks that encounter this issue may want to know this. Basically, I never got any blinking 4WD lights (even tho MM button was in 2WD position, truck was in 4WD based on physically testing the yolk) and I figured it meant that ECU was forcing this into 4WD and hence why it never was showing blinking 4WD lights because that's what it was telling the actuator to do.

power10er

I have a 97 Limited 4runner and I am trying to locate my 4WD ECU. Any help will be appreciated. There are so many conflicting and vague resources online.