4 Wheel Drive Problems

[Takemetotheriver]

I have a 1997 4runner limited with automatic transmission. The 4 wheel drive has been acting up and not engaging. When I hit the 4 wheel drive button I can hear something engaging, or partially engaging, which I assume is either the solenoid or the actuator. I have tried numerous combinations of driving at different speeds when trying to engage, engaging from neutral, turning the truck off and then back on, trying 4 wheel low(it does go into low gear, but it does't seem like the 4wheel is engaging). I do hear an electrical and mechanical response when I hit the button, but there is no solid or blinking light on the dash, and the vehicle remains in 2 wheel drive. Any advice, suggestions, photos, diagrams (I have the haynes book) would be appreciated. Heading down to the beach to fish this weekend and don't want to see my beach buggy pass go to waste. Thanks in advance for any help or advice.

 

[Skidmarcx]

Sounds like the tcase is engaging... Verify that the front diff is engaging the left side axle... You can manually apply vacuum to verify the diaphragm is good and troubleshoot from there

 

[Takemetotheriver]

Where and how would I manually do that?

 

[TheDurk]

Where and how would I manually do that?

Something I wrote that I post a lot:

VSV’s/ADD
Don't guess at it, troubleshoot! Start at the twin VSV's (Vacuum Switching Valves) on the driver fender wall. There are two long vacuum hoses that come up from the diff, one goes to each VSV. Check to see that one of the two hose nipples on the VSV’s has vacuum (engine running, 4WD NOT engaged. If no vacuum either side, check the check valve going to the intake manifold and look for loose hoses or a hole in the reservoir. If there is vacuum going to one hose, then put it in 4WD. See if the vacuum switches to the other hose. If it does, and no 4WD, problem is the diff actuator or the line to the diff. If it does not, then just switch the hoses and you should go into 4WD. This confirms diff is okay.

OK, switch them back. Then use a test light to see if electrical signal from the TC also switches sides of the VSV. If it does not, problem is the TC, the switch on the TC, or the TC actuator, or its wiring back to the button (last two for non-J shift only). If it does, but the vacuum does not, the problem is the VSV itself.

I start troubleshooting at the VSV's because you can figure out where the trouble is without having to climb under the truck.

EDIT: Post #2500!! Yay, me!