1995 Tacoma 3.4l front diff/4x4 issue.. VSV?

F6 is the 4WD ECU.

 

Found some better diagrams WITH the 4WD operation.
This should help A LOT.....

 

This is great and very much appreciated! Hopefully this is enough.

Thanks to both @TnShooter and @Strictlytoyz

 

Update: the 2-4 selector switch has continuity. I pulled the plug out of the 4WD ECU to test. Ignition ON - I have solid ground with WB wire continuity to frame.
I have 12v power from: PG wire which I believe is V4, YB 12v power and GB. I believe the YB feeds transfer case selector and GB goes to oil sensor based on diagram. No other terminal has power. I tested all while running and in both 2-4 selector positions.
The way I am reading this is, only one VSV is getting power. And if it’s not getting power from the ECU, it’s probably not the VSV, but the 4WD ECU.
What I don’t understand is, if transfer case is truly getting power, I would think the front drive shaft would lock. And the VSV would have nothing to do with that. Unless the front differential selector sensor coordinates with the transfer case in addition to the power input from the 4WD ECU.

I’m sure you guys are sick of this but I appreciate your input and correcting me in my observations…assuming I didn’t mess up any test.

Also, I don’t think the diagram is 1995 year specific so the color of wires may be different on my truck than the diagram.

 

OP are you saying that when 4Hi is selected, your front driveshaft doesn't spin when you put the truck in drive and move forward?

If that's the case then your problem is further back than the front diff. The transfer case engaging the front driveshaft sends a signal through a transfer position indicator switch to the 4WD ECU to then send power to the appropriate VSV to engage the ADD actuator.

Might want to check resistance and continuity of the transfer position indicator switch on the t case.

 

I don’t have 4H I have the original 2-4 selector button on TC shifter(L4 - N - H). Maybe that doesn’t matter…

 

So if you leave it in H, but push the selector button that is 4Hi. Pushing forward to Low is 4Lo. Does the front driveshaft engage (spin) in either 4Hi or 4Lo?

 

No it’s free in either selection. That’s with all 4 wheels on the ground.

 

That's a problem. Transfer case isn't engaging

 

Which one is the transfer case position sensor you mentioned?

There’s 2 plugs on the TC actuator and there’s one way up close to body. I’m assuming it’s this one.

 

Yea should be the one way up close to the body near the top of the tcase

 

Ok. Can I check continuity on the plug coming into it or is there another way to test the sensor?

Thanks!

 

You'll have to remove it (should be like a 22mm or 24mm), and then test it per this:

 

Has anyone removed this? Could you just unplug it and push the 2-4 selector while testing continuity on the pigtail?

 

That might work actually. Should be very easy to remove though. I've removed the front diff one (same exact part - just different location).

 

Access is tight, might have to drop transfer case slightly, and you'd have to use open end wrench or open end socket attachment because of the wires attached.

 

Yea I'd jist unbolt the transmission crossmember while supporting the tcase with a floor jack and then lower it an inch or two to get better access