moots

Sorry if this has been addressed before but here goes;

98 4runner manual transmission has the following symptoms:

4WD Low (Works great but no dash light)
4WD High (Does not work at all and no dash light)

Any ideas on the issue ?

Don't have a manual to look for vacuum hoses or switches but it's weird why LOW works and HIGH does not ??

thanks,

Dave

raydouble

I'll bet you are going into low range 2wd and not 4wd at all.

Search around for threads, there a whole lot of them.

I think your truck came with a vacuum actuator (i think) there were also, electric ones....don't know when that changed.

moots

It's possible you are correct that it's 2WD Low only as it's turning easily...I have looked at the vacuum lines and fuses but cannot see anything wrong.

I have been checking various threads here as well, not sure what to check...

thanks,

Dave

raydouble

......

99yota4

sounds like the same problem as me. Still haven't solved mine but I have a good idea as to what it is, just gotta find time to get to it. Basically, I am not getting a voltage (signal) to the VSV (vacuum switching valve) for the front A.D.D (automatic disengaging differential). By shifting the 4wd lever into 4hi or 4lo, the propeller shaft is spinning, but the sleeve on the front axle doesn't slide and lock. It is supposed to slide over a cutout and LOCk the hubs. I tried switching vacuum lines around on the VSV and I can get it in 4wd. I've tested the 4wd by getting stuck in 2wd and then swapping vacuum lines and engaging 4wd and getting out of it. Therefore, I know my actuator, and vsv are good. In the circuity of the system, there are 2 4wd indicator switches on the transfer case, and then the 4wd relay. I'm almost sure that it's the wiring along those lines that is either cut, disconnected, or not sending a signal. In order for the indicator light for 4wd on the dash to light, the switches on the transfer case AND the switch on the front diff must acknowledge that the truck is in 4wd. I'll try to keep you updated, but if you find your solution, let us know! I have a thread on here or t4r.org somewhere.

TheDurk

Find the VSV's on the driver's fenderwall. First, make sure there is good vacuum from the manifold TO the VSV's, (top holes). If not, check the check valve and look for leaks. See which VSV has vacuum on the bottom hole connected to the hoses that go down to the actuator on the diff. Put it into 4WD and see if it switches sides. If it does, problem is in the front diff. If it does not, then get a DMM or test light and see if the 12V signal is changing sides. If it does, you need a new VSV. If not, problem is in the wiring from or switches on the transfer case.

99yota4

From what I remember, (i did alot of the trouble shooting a couple month ago), The VSV does not switch over when shifted into 4wd. BUT when I manually swap the hoses (the bottom hoses that run to the front diff), I can engage 4wd without the indicator light. Could you clarify how to check the signal with the DMM on the VSV and also for the switches or the wiring. Thanks Durk

TheDurk

Each VSV will have two wires, a ground and a 12V+ that tells the VSV to pass vacuum to the front diff. To identify which is the ground, pull the plug, put your test lamp wire (or DMM lead) on the positive and test both wires in the plug with the probe. If it lights up, that's the ground. So you are interested in the other one. Switch the test light lead to any old ground and put the probe to the 12V+ wire in the plug. Then cycle the trans from 2WD to 4HI and 4L. The light should be on or off for one or the other. Then repeat with the other plug. You should get the opposite pattern.

If it's not like that, the problem is between the VSV's and the transfer case. As I recollect, you have an auto and that's a different circuit and a different TC than what this poster and I have. So I can't help you there with specifics. From the VSV's forward, auto and manual are the same (except for late models with electric actuator and no vacuum at all).

99yota4

I'll try to work on it today, I need to figure out how to use the DMM for testing continuity. Thanks!

99yota4

So I checked voltages on the VSV plugs. The Brownish Red solenoid side (2wd) has voltage on the greenish wire and the white wire is ground, while the Blue solenoid has no voltage.
I shifted the vehicle into 4wd and checked the same wires for voltage and there is no change. Voltage is only being sent to the Brown (2wd) solenoid side. Re-checked the vacuum lines and those are good, good vacuum being send from the intake manifold to the vsv's. What do I test for next? Thanks in advance

TheDurk

Here's where I have to be honest and say I don't know. Your machine is different than mine and I haven't even had to work on that part on mine. There are position switches on the TC, and there may be a relay in the middle that are responsible for sending voltage to the blue solenoid once 4H or 4L has engaged on the TC and cutting power to the brown one. Ideally, you could pull those switches and test them but I have no idea how hard that is to do. I don't even have access to a circuit diagram for your model, just the 2002 all-electric one. Hopefully, someone else will chime in.

99yota4

TheDurk, all I can say is Thank you for all your help up till this point. Now i've been able to narrow down my problem and like you said, hopefully somebody can chime in and help me find my solution!

I believe you are over on T4R on my thread about 4wd not working...
http://www.toyota-4runner.org/3rd-ge...lem-4wd-3.html


Anybody? (99 4runner 3.4L 5vz Auto trans, J-shifter NOT multimode)

TheDurk

To the OP in this---I disagree with Ray. If the light is coming on, you ARE almost certainly in 4WD. I don't see how you could get a "false positive." I had this same set of symptoms--and I have the exact same drive train and year as you do--while I was still in warranty. The dealer had just replaced the clutch and found they had left a wire off one of the TC position switches. My guess is your 4H position switch is not working or its wiring is faulty.

And sorry for the hijack.

99yota4

Anybody able to help me out here?

kerelawsurf

drop the oil out of you diff and see if you have any steel filings in the gear oil, i have the same prob as you lot , i had a smashed front diff on the planet or sun wheels that's how i only had rear wheel drive and the diff was quiete as a mouse no whinning or grinding sound from the front diff. so drop the diff oil boys

justin_4runner

99yota not sure if u fixed the problem or not but i have a 91 and it has the add system, from what i have learned couple things to look at first is the postioning switch on the tc to make sure it is sending power to relay telling it to send power to add solenoids.. if u are not getting power to solenoids check the position switch on transfer case for conituity threw switch when in 4h and 4L if u do then pull relay location under the dash by steering coilum i would put power to it and see if it switches or not, if not replace and so then i would say u have a bad wire somewhere or connection. hope this helps,

dirtymotoman

Have you tried changing out the indicator bulb?

gornish_hick

where on the TC was that 4H switch located? I'm having this no 4WD problem too. mine all started like you when i replaced the clutch and i lost my 4H. that was about a year ago. i figured it was electrical but since i don't really use the 4H i didn't really worry about it. Well just recently i lost my 4L and i'm thinking it has something to do with wiring or a switch

If anyone has figured out there problems about this type of issue id really like too hear where and what it was?