4 wheel drive problem (4wd)

[99yota4]

4 wheel drive problem (4wd) FIXED*

Hey guys, I previously posted that I wasn't sure if my 4wd is working or not because the indicator light on the instrument panel doesn't turn on. Well, I found out that it is not engaging what so ever. I tried all the different "techniques" from shifting from 2Hi to 4Hi at a stand still in Drive with the wheels straight, to the slow straight line shifting and also the reverse for both. I also tried shifting into 4Lo while in Neutral and still nothing.

I have done a search of troubleshooting this problem and didn't come up with alot of good results. So far my leads are: Actuator, Vacuum lines, or solenoids. I'm not very familiar with the way the 4wd system works on these 4runners so if anyone knows a good resource to get more knowledge or wants to share some, that'd be awesome! Thanks in advance!

**1999 3.4L V6 Auto w/ "J" shifter

 

[Elton H]

id check some of the vac lines first make sure theres no ripps

 

[TheDurk]

After the hoses as above, the first thing to check (because it's cheap and easy and nothing works without it) is the one way check valve between the manifold and the VSV's(Vacuum Switching Valves). Find the two VSV's on the driver's side fender wall--the short VSV hoses go to a mini-manifold that connects to a reserve canister and also receives vacuum from the engine via the check valve. One long hose goes from each VSV to one side of the actuator in the front diff.

Make sure there is vacuum present at this mini-manifold. If not, then pull the check valve and blow into it both ways to check one-way function.

If there is vacuum, then verify that one VSV on the fender is sending vacuum to the front diff. and one is not. Then switch to 4WD and see if the vacuum switches VSV's. If it does, problem is in the front diff. If it does not, problem is electrical and you need then check the switch on the transfer case. If one VSV turns on and off and one doesn't, you have a bad VSV.

That should get you started.

 

[TheDurk]

This recent thread has some good info, including the article linked in post #3.

 

[Elton H]

free bump

 

[99yota4]

Hey guys, I got my 4wd to work! The picture below is the manifold assembly for the 4wd and the vacuum lines.

I'm borrowing this picture from a thread on ttora. Anyway, the two lines connected to the green housing is where I found the problem. I believe the VSV is bad on one side. When I swap the hoses on that bottom part of the green housing (closer to the electrical socket) I feel my 4wd engage immediately!

It's kinda like having manual hubs where you have to go outside and lock them. But instead I have to go out and swap those hoses around to engage 4wd and swap them back to disengage the system! I'm fine with that for now until I can find the part at a junk yard or something.

Can anyone tell me what exactly the problem is? I'm just pretty happy that I can get my truck in 4wd right now!

I just double checked and when the shifter is in the 2wd position, the brown side has vacuum.

 

[Elton H]

time to hit the malls now

 

[TheDurk]

Congrats. You have eliminated the front diff and the vacuum supply as possible causes. Now you need to determine if the VSV's are receiving the correct electrical signal and are mechanically unable to respond or whether the switch on the transfer case is not telling the VSV's to switch the vacuum hoses on and off.

I'd put a test light or DMM on the hot wire leading into the brown and green sockets in the picture (not at the same time, but first one and then the other). Voltage should move from one to the other as you switch the system into and out of 4WD. If it does not, you have to consider the switch on the transfer case as prime suspect, if the front drive shaft in fact engages. The shaft should lock up in 4WD but you can turn it by hand in 2WD. If the voltage does switch, then try it with the long hoses disconnected and feel which VSV is not responding by putting your finger on the green nipple to feel the vacuum going on and off. That VSV will need to be swapped.

You can also check the resistance of each VSV solenoid. Spec is 37-47 Ohm.

 

[99yota4]

Durk, So I got the 4wd to engage by switching the vacuum hoses around. And I have to switch it back when I want to disengage and go back to 2wd. Doesn't that mean the VSV is bad because it's not switching to the other valve when the 4wd shift lever is shifted? I'm a little confused. I'm thinking I can check which side has vacuum in 2wd and then see if it switches over to the other green housing when it's in 4wd.

On a side note, I was under there with a buddy of mine and inspecting the transfer case. It was obvious that someone was under there before me and messed with it a little. On the passenger side of the transmission, there is a wire harness that's connected, however on the driver side of the transmission i saw a wire harness just sitting there and not connected to anything. Can anyone tell me what that's supposed to be connected to or have a picture? The runner runs smoothly and I haven't had any problems with it. I'm assuming that it's a pre-wiring for an e-locker or something of that nature?

 

[99yota4]

I went to the junk yard and found a 4wd T100 and a 97 4runner limited. I grabbed the VSV's from both. I tried swapping out the VSV to find that they all did the same thing. Only vacuum coming from the brown side. I looked at the actuator and everything seems fine there. All vacuum lines are connected. There's a gray wire harness on the rear side of the actuator that I noticed was cracked but the connection is being made.

Problem that still persists:
1) 4wd indicator light doesn't turn on what so ever. No flashing no nothing.
2) 4wd does not engage normally. Only when I get down to switch vacuum lines on the VSV as pictured above. I switch the hose with the blue stripe with the wire to the left of it in the picture. The brown side is where I have vacuum.

Can anyone help? PLEASE? Thank you

EDIT**
I also just tested the original VSV voltage as theDurk recommended. There is only voltage on the brown side (14Volts) in both 2wd and 4wd. What is my next step?

 

[TheDurk]

EDIT**
I also just tested the original VSV voltage as theDurk recommended. There is only voltage on the brown side (14Volts) in both 2wd and 4wd. What is my next step?

OK--I didn't see this because you posted by an "EDIT". That doesn't bump the thread so I didn't realize there was new info.

You now know your ADD system is working fine, but the transfer case is not telling the ADD system when it is time to engage. You are getting into territory where I can't help much, as I am a 5sp manual guy. Since my first car in 1973, I have never owned an automatic. I can barely drive one--I keep slamming on the brakes when I try to clutch in a rental.

As I said before, if the voltage is not switching from brown to green at the VSV's, then lead suspect is now the sending switches on the transfer case. There may be a relay in the middle, too, located on the passenger firewall. There is more than one transfer case for the autos and more than one control setup in my FSM so it's hard to help over the internet on something that is different from my truck.

About all I can tell you is to get under there and look at the transfer case. See if you can find the position switches that tell the ADD system to engage. There may be two, one for 4Hi and one for 4 lo. You should be able to get them off and check their function with an Ohmmeter. Clean those connections well and check their condition--I lost my 4WD once when mice were eating on those wires on top of the transfer case. This may be where the loose connector is supposed to go. If you have the relay, there is a test in the FSM. ncttora has them online.

Also, make sure the front drive shaft locks up when the transfer case is in 4WD. This means the switches aren't sending the signal because 4WD is not, in fact, engaged and the problem is inside the transfer case(=not good).

 

[99yota4]

I've looked at the FSM a couple times and can't find much about the switches. I am pretty confident that the problem is the switch or the ADD relay because those are the things that are tied into the circuitry for the 4wd indicator light which never turns on. Does anyone know where that switch is located and how to test it? I'm a bit confused as there are a couple different switches. There is the ADD indicator switch located on the actuator and there is a 4wd switch. I'm thinking that one is near the transfer case. The 4runner FSM is not that detailed compared to the earlier model pickup FSM. I've been using both for trouble shooting.

 

[TheDurk]

Your problem is NOT the indicator switch on the front diff. That only helps turn on the light. It has nothing to do with causing the vacuum to switch between red and green. You should focus on the transfer case switches and the ADD relay (if you have it). This is how the transfer case tells the ADD system it is time to engage by switching the voltage to the VSV's and this is what is not happening.

J-handle>>Transfer case>>Position switch on TR. case>>Relay (if present)>>VSV>>Front Diff>>Indicator Switch>>Light on dash

The light comes on when both front diff and transfer case report they are in 4WD. So if you get the voltage to switch from brown to green at the VSV, the light should then work, too.

Do you have the relay? I don't have experience with the autos, but it would seem the J-handle would mean no relay.

 

[99yota4]

Thanks TheDurk. I'm not sure if a I have the relay. Where would it be located? I heard passenger wheel well but I don't see anything like that. I also heard passenger side kick panel? I'm with you though, I have the same 4wd shifter as you i believe. the only different shifters were between the 96-00 and 01-02 that had the button on the shifter (multi-mode 4wd) and also those came with the limiteds.

I don't know where the switch is on the front diff actuator. I was able to locate the vacuum lines on the actuator and I also found the wire harness (which i believe is the switch) the plastic harness on that is cracked and when I pull it off, the 2 metal prongs are exposed on the actuator side. Should I try testing for continuity on that? What else could I check? Would it be possible to IM text or call to get communication faster?

 

[99yota4]

Here are some interesting findings. Something told me to switch the VSV hoses to where it engages 4wd. I decided to drive around with the hoses that way around the block and test out the 4wd shifting. I noticed that with the hose with the blue stripe connected to the green nipple on the brownish red side of the solenoid I am able to shift in and out of 4wd with no problem! I can hear the system click when it disengaged 4wd and goes into 2wd. I can't hear anything when it engages 4wd but i can tell by the weight of the wheel and how the tires are making the gripping noise on asphalt. Did I solve most of the problem just by switching vacuum hoses around?

Problem that still exists: The 4wd indicator light doesn't turn on. Should I continue to test the continuity of the 4wd switches on the transfer case? According to the FSM, there are 2 switches on the transfer case for 4wd. TR-10 of the FSM shows No.1 4wd switch and No.2 4wd switch. could it just be a indicator light bulb that is out?

 

[TheDurk]

Thanks TheDurk. I'm not sure if a I have the relay. Where would it be located? I heard passenger wheel well but I don't see anything like that. I also heard passenger side kick panel? I'm with you though, I have the same 4wd shifter as you i believe. the only different shifters were between the 96-00 and 01-02 that had the button on the shifter (multi-mode 4wd) and also those came with the limiteds.

I don't know where the switch is on the front diff actuator. I was able to locate the vacuum lines on the actuator and I also found the wire harness (which i believe is the switch) the plastic harness on that is cracked and when I pull it off, the 2 metal prongs are exposed on the actuator side. Should I try testing for continuity on that? What else could I check? Would it be possible to IM text or call to get communication faster?

Is this fast enough? Yeah, the only wires into the diff are the indicator switch. It should have continuity in 4WD and open in 2WD (I assume). It looks like it just unscrews and then its push=closed, free=open. But it's not your problem. Or not your only problem.

The ADD relay is in the rear corner of the passenger side of the engine bay. It actually looks to be more on the firewall than the fender wall. You actually SHOULD have it, as it is labeled "w/o 2-4 selector" which I understand to be your case. I would try to check that next, if it is there. Let me know and I'll walk you through it.

Do you use GoogleTalk? Thats my only IM.

 

[99yota4]

I'm looking at the passenger side kick panel. There is a relay that is labeled "transmission relay" I believe this is the one.

Pm'd you about IM. Thanks for all your help.

 

[99yota4]

Here are some interesting findings. Something told me to switch the VSV hoses to where it engages 4wd. I decided to drive around with the hoses that way around the block and test out the 4wd shifting. I noticed that with the hose with the blue stripe connected to the green nipple on the brownish red side of the solenoid I am able to shift in and out of 4wd with no problem! I can hear the system click when it disengaged 4wd and goes into 2wd. I can't hear anything when it engages 4wd but i can tell by the weight of the wheel and how the tires are making the gripping noise on asphalt. Did I solve most of the problem just by switching vacuum hoses around?

Problem that still exists: The 4wd indicator light doesn't turn on. Should I continue to test the continuity of the 4wd switches on the transfer case? According to the FSM, there are 2 switches on the transfer case for 4wd. TR-10 of the FSM shows No.1 4wd switch and No.2 4wd switch. could it just be a indicator light bulb that is out?

What should I test next to get that light to turn on. I'd like to get it working. No problems with the 4wd so far. I took it to a hill where there is loose gravel. In 2wd I spin at the rear wheels and don't move. I shift into 4wd and i'm up and through the loose gravel. AWESOME. Just have to figure out the light now!

 

[GbRunner]

I didn't read throughout all the posts, just kinda skimmed through it. butttt, could it maybe be a fuse? I know there's one in fuse panel for 4wd.

 

[TheDurk]

What should I test next to get that light to turn on. I'd like to get it working. No problems with the 4wd so far. I took it to a hill where there is loose gravel. In 2wd I spin at the rear wheels and don't move. I shift into 4wd and i'm up and through the loose gravel. AWESOME. Just have to figure out the light now!

I have bad news for you. The problem is not just the light. What you have done is create a situation where the front diff is always engaged. So when you go into 2WD you are disengaging the transfer case from the drive shaft but the wheels are driving the system all the way back through the front drive shaft to the front of the transfer case. This will cost you wear and tear on the front drive train and maybe an MPG or two. To confirm this, try and turn the front drive shaft by hand when you are in 2WD. It should turn by hand--I bet yours doesn't.

You need to focus on the switches and wiring between the T-case and the VSV's. That signal is not getting through. Fix that, and the light should take care of itself. Unfortunately, that part of the system is different than my 5sp and I can't tell you exactly what to check. The on-line wiring guides are no help either; they don't cover your non-button system. It would be nice if someone with a non-button auto trans could chime in here. Is there an ADD relay and where is it? Where exactly do the wires go next from the VSV's? The relay, if it exists, is a logical suspect because you have a problem in both 4H and 4L and I believe your T-case has two separate position switches, one for 4H and one for 4L. So a relay could cause a problem on both but one switch could not. And the test procedure is in my '99 FSM.

The good news is you have proved the T-case is fine mechanically and that the problem is merely electrical. There is a 4WD fuse but I didn't think it was the problem because you have power to the VSV's, it's just not moving from side to side. Still worth checking, though. Conceivably, the control function is on the fuse but the applied power to the VSV's could be from a different circuit in the engine bay.Again, if I had access to a wiring diagram I would know. Maybe I should spend the $49 and buy the '99 Wire Guide now that my truck is getting old.