Hello! I have been reading this forum for some time now, including several related to the issue I am having but I am still coming up short.

I have a 95 4Runner SR5 v6 with an automatic transmission. The 4wd will not engage. I hear the ADD relay under the dash click repeadetley but nothing happens. I've even tried throwing it back and forth from drive and reverse to see if this will help the problem at all but no dice. I have tested the VSVs on the passenger side fender, the vacuum tank, actuator on the front diff as well as the lines for cracks or holes. Everything holds vacuum and everything seems to be in good working order. The actuator does not engage, even when vacuum is applied manually so I do know that this needs to be inspected. When I shift to 4hi or 4lo there is no change at all, even in the rear.

What I am hoping someone could help with whether or not there is something at the transfer case that could be causing the issue. I know that the transfer case switch could potentially be a part of the issue, but is there something else that could be preventing it from engaging? Any help would be greatly appreciated. thank you!

 

Check for Transmission codes: http://web.archive.org/web/201408161...31diagnosi.pdf
The A340H (which I assume is your transmission -- check the sticker on the door pillar) has an integral transfer case. If the #4 solenoid fails it won't shift.

But that's not your ADD problem; vacuum manually applied SHOULD move the actuator, no matter what the transmission is doing.