Here's the deal, 96 4runner limited auto (with push button 4wd). I do the monthly 10 mile exersice to keep the system "working" right. I did a bit of beach wheelin in the outer banks in September and since about late October the 4wd would not disengage unless I turned the truck off and restarted it. This happend about a half dozen times. A couple of weeks back when we got our first snowfall, nothing, no dash light, no 4wd hi or low. Fuse and vacuum lines all check out and a multimeter shows the 4wd button on the shifter to be functional. I inspired by some other threads jumped ahead to the front diff ADD switch but that checked out ok as well. I also checked the resistence on the soliniods. I hooked the battery direct to the soliniods but would I only have air blowing if the engine was on? I could not tell if air was coming from a port because of the turbulence of the motor. I need to grow another hand. There is a check valve on the vacuum line coming from the throttle body. Should I be able to blow through this thing on a given end ? Its like blowing through a rock . Is this thing clogged or does it take alot of pressure. I used a solid piece of hose to temporarilly bipass it but it did not seem to do dittally.

If when the engine is on and idling and I push the 4wd button and there is no visual change in the soliniods ( 1 up 1 down) What does this mean?

Where is the 4wd ecu control on this model?

Sorry for all the questions but I'm lost and really cant afford to get raped by the stealership. Thanks in advance for any insight.

 

I'm not sure which one but there is one of the solenoids that hangs up. There have been quite a few of these with this problem. Get a EWD of the 4wd solenoids and like you were doing, use battery power to manually move them

 

I think the soliniods R activated by the vacuum or air pressure but I'm not sure. I dont hear a thing when I try to engage the 4wd other than the click of the button itself. I'm leaning toward the ECU computer but that can be a expensive guess .

 

Yah its doubtful its the ecu. Ive never seen one of those go bad. Dont try and throw parts at something. I'm betting 99% its one of your solenoids, either the one for the front diff or the one on the trans case