Can someone explain '01 Transfer Case Switches?

[ArmArak]

Hi guys Merry Christmas!

My 2001 4Runners 4WD drive system has been sluggish to say the least. Everything technically works; however, not very well. Engaging 4WD takes on average around 45 seconds with the lights blinking on the dash. The center diff locker takes even longer to engage/disengage. The lights flash until I hear it click into place.

I changed the transfer case fluid around 2000 miles ago (at 96000 miles). I found out that transfer case switches are a common problem in the multimode system but I haven't seen a good explanation of how the system works and what the switches actually do. Could someone please explain how many switches there are and what they do.

Also any other troubleshooting tactics would be appreciated

EDIT: I would also like to note that my VSC system engages at almost every stop regardless of road condition when I am in 4WD. I am wondering if the VSC system can affect the transfer case engagement.

Thanks!

 

[Cree]

So you have a VF3AM case. I'm sure someone will correct me if I'm wrong, but here is my understanding of it.

You have 3 position switches in the system, 2 in the case and 1 at the front diff. You also have the electronic actuator. Your 4wd and center lock buttons both send signals to the 4wd computer which then fires up the actuator either once for open center operation or twice for locked. The switches tell the computer when that actuator has moved the appropriate parts to where they're supposed to be for the selected mode of operation.

Your lever simply moves the internals from high to neutral and into low. There's another sensor internal I believe that signals 4 low.

Usually when my car is being picky, I go straight to low, then back to what I want. Think my actuator is on the way out. If it's slow no matter what, I would suspect the same for you.

 

[ArmArak]

So you have a VF3AM case. I'm sure someone will correct me if I'm wrong, but here is my understanding of it.

You have 3 position switches in the system, 2 in the case and 1 at the front diff. You also have the electronic actuator. Your 4wd and center lock buttons both send signals to the 4wd computer which then fires up the actuator either once for open center operation or twice for locked. The switches tell the computer when that actuator has moved the appropriate parts to where they're supposed to be for the selected mode of operation.

Your lever simply moves the internals from high to neutral and into low. There's another sensor internal I believe that signals 4 low.

Usually when my car is being picky, I go straight to low, then back to what I want. Think my actuator is on the way out. If it's slow no matter what, I would suspect the same for you.

OK that's what I thought was going on. What's the sequence that is followed from press to actuation? If I understand correctly it goes something like this?

1. Press 4WD Button
2. Actuator Engages 4WD
3. Switch Detects 4WD is engaged
4. ADD engages
5. ADD switch confirms ADD engagement

If this is correct do the 4WD lights blink between steps 2 and 3?

Thanks

 

[Cree]

OK that's what I thought was going on. What's the sequence that is followed from press to actuation? If I understand correctly it goes something like this?

1. Press 4WD Button
2. Actuator Engages 4WD
3. Switch Detects 4WD is engaged
4. ADD engages
5. ADD switch confirms ADD engagement

If this is correct do the 4WD lights blink between steps 2 and 3?

Thanks

It's something like that yeah. I think the computer looks for conformation from the case and front diff before the light stops. So it should blink all the way through the sequence.

You can hear the actuator with the key on and the truck off. Front diff requires vacuum.

 

[96RedRunner]

[MENTION=511254]ArmArak[/MENTION], 01's take getting use to, I hit 3 yr mark.
Owners manual tells operation usage, light condition etc. FSM easiest way to understanding troubleshooting.
Slugish engagement - normal for any 3rd Gen, don't use it ya lose it engage it often.
VSC over active - needs calibration Dealer easiest route cost 1hr @ hourly rate for me that $139.
Procedure for DIY VSC cal and a second procedure that needs doing around net, my links dead.


@Cree, just saying 01's went servo motor on front diff.

 

[Cree]

[MENTION=511254]ArmArak[/MENTION], 01's take getting use to, I hit 3 yr mark.
Owners manual tells operation usage, light condition etc. FSM easiest way to understanding troubleshooting.
Slugish engagement - normal for any 3rd Gen, don't use it ya lose it engage it often.
VSC over active - needs calibration Dealer easiest route cost 1hr @ hourly rate for me that $139.
Procedure for DIY VSC cal and a second procedure that needs doing around net, my links dead.


@Cree, just saying 01's went servo motor on front diff.

Good to know.

 

[phattyduck]

If it does work with time, just keep exercising it. It'll get faster.

Like, do it every day on a straight section of road. Maybe even multiple times.

In your list above, the 4WD lights will flash anytime the system is between steps 1 and step 5.

-Charlie