FJ62 4WD not working,,,, (1 Viewer)

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Apr 11, 2019
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Location
new york
we got our 1st taste of snow & went to put my new FJ62 in 4WD, locked the hubs, pushed H4
button & it does not engage,, I am assuming that it is supposed to click & stay in when working,,,
(& no 4WD light when holding in), on looking through some threads it looks like I will start by checking my
vacuum lines to solenoids,,, the other threads seem to be saying they have an issue with 4WD light staying on,, not my situation,,
Does any one know if the H4 switch would not click in with a vacuum problem or could i have a bad H4 switch?
Any advice is greatly appreciated
thks
 
The 4WD light is turned on by a ball switch mounted to the T-case. When the shaft moves to the 4WD position the ball finds a detent in the shaft and turns the light on.

-4WD switch requires power to it-check power
-4WD switch sends power to vacuum solenoids- check power
-Solenoids transfer vacuum to diaphragm on T-case- check solenoids, vacuum supply hose,vacuum
hoses to diaphragm
-Diaphragm moves shaft into 4WD- check diaphragm
 
are you sure it is not engaged? don't trust the light.
with both hubs locked, does the driveshaft rotate by hand?
both hubs unlocked, free position, engine running push button for 4wd, does the driveshaft rotate by hand?
 
If I don't use mine for awhile it takes some time to decide to shift into 4wd. I have helped it along in the past by whacking the transfer where the vacuum lines go in with a rubber hammer. Usually that works. Now I engage it every month or so to keep it cooperative.
 
Thanks for suggestions,, will check them out
Any advise on switch does not click in,, push it in & it just springs out,,,would this happen with other issue?? or am I just looking at a bad switch?

image.jpg
 
The switch should click into the 'in' position for 4WD. Maybe start by replacing the switch?
 
Thks & will do
Any idea of wht the light gray adjustment thing is on the switch?

E27AAB3F-F522-4427-B34D-8508AE94BD63.jpeg
 
I would try manually swapping the vacuum lines in the engine bay to engage 4wd, that test is fast and free and lets you know that everything south of the firewall vacuum solenoids is good. Search around and you should be able to find which lines to swap on here. Then work your way up from there. You should be able to bench test the switch with a multimeter but I would start with the actual vacuum system first. That is almost always where the problem lies due to 25-30 years of prior owner disuse, everything is either just stuck together or the lines are all original and dry rotted and not holding vacuum. Or both.
 
1
There are 2 vacuum switching valves on the passenger side of your firewall. If the one VSV fails it engages the 4WD. Odds are the vacuum lines aren't the issue.

Before you get into the switch on your dash, manually shift it into 4WD low. If 4 Low works then....

2
Shift back into hi gears, push button and get under truck and see if the front driveshaft turns (manual hubs must be UNLOCKED).

3
If that doesn't work it's time to test the switch on your dash.
 
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You can simply switch the two lines from the vsv to t/c vacuum shifter pod. One vsv (2wd) will have vacuum and the other (4wd) will not. Mark them for the stock orientation so you can return them once you trouble shoot.
Cruiser running for vacuum supply,parking break set and hubs disengaged. Front driveshaft will rotate in 2wd. Switch vacuum hoses and front driveshaft should be engaged with t/c. Lock hubs to engage front wheels.
If that works you have eliminated diaphram shifter, your cause is either the switch or vsv.
Good thing about testing this way is you can now engage 4wd without having to have the switch. Just don't forget to switch it back.
This is a very simple mechanical t/c with electric doodads to make engaging 4wd easy. Use the above method for now and work on the rest as time allows.

That light grey adjustment thing is a small lightbulb holder iirc.
 
Switching the lines is 95% probability not his issue. When the VSV fails on the firewall it stays in 4WD. The fix is usually to get it out of 4WD.
 
Switching the lines is 95% probability not his issue. When the VSV fails on the firewall it stays in 4WD. The fix is usually to get it out of 4WD.

Maybe I reread it incorrectly. The goal is to activate 4wd correct? As long as there is vacuum to the shift fork via vacuum diaphram it doesn't matter which vsv is active. Vacuum should be present unless the diaphragm is shot( highly unlikely). It's a matter of engaging the shift fork.
This is the exact same style of vacuum shift on early Landcruiser in function. Early one is a pullcable that activates a vacuum switch mechanically. 62 is an electric version of the same basic design.
Troubleshoot the dash switch and vsv is basic multimeter 101. Getting your 4wd working in a pinch because the roads are slick is the goal here if I am understanding the question.
 
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My vacuum valves failed in the open position. I haven't found a good aftermarket solution that seems to work, so I just swap the lines whenever I need it to work.
 
The VSV's are cheap to replace if you know what PN to order.

@bryman,
Any updates on your diagnosis?
 
Thanks for all the info,, been jammed at work,, hope to go through diagnostics tonite,,, In meantime I found & have a switch in route,,, that my current one doesn’t click in,,, I figured even if it is not the fix,, it most likely is NG, I hope to get by tomorrow
 
I got the H4 switch,, & it clicks in,, mine was definitely NG,, I put it in this morning hoping it was the fix but ☹️,, I locked hubs pushed in H4 button and no light,, went under & front drive shaft is free,,, then tried to shift to L4& shifter does not budge from H2,,,
Pulled forward & backward a little bit & the same,,, Are the hoses in pic ones to switch?
Thks

01E1FAD9-DB0B-4A0B-9D78-7F440B7A7C85.jpeg
 
The two lines with the arrows go to a Y, that is your vacuum source. The two green ports are the switched side. With the Cruiser running you should have vacuum at one of those ports with switch off. Engaging the switch should transfer vacuum to the other port/ vsv. Did you unhook the lines in your pic or was it like that?
 

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