4wd not engaging 1988 fj62

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Are you saying that when shifiting into low mechanically should put it into 4wd? Thats what what it sounds like your saying and it doesn't work this way in a 62. The lever is just a range selector, and the switch on the low range switch on the tcase is what switches the VSV's into 4WD 'mode'.

Randy88FJ62 said:
If your 4WD Lo manual shifter(and linkages) doesn't engage 4WD then the problem is not in the VSV's or the hubs.

php74 is probably asking you to confirm that with hubs locked you can't turn the driveshaft. If you can't that at least confirms the hubs are working.
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Threeeeyedbandit,
My truck can go into 4Lo by moving the shift lever. The 4WD switch (for 4Hi on the dash) does not need to be selected. 4Lo engages 4WD regardless of switch position on dash.

ReCruiser,
Yes the thing bolted to your tcase that the VSV lines go to is your diaphram.
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I am going to use a vacuum pump to apply major vacuum to that diaphragm. If it works and I get vacuum, my solenoid should actuate and I will not be able to turn my driveshaft?
I am going to follow this to its logical conclusion thinking that it is still a vacuum issue until proven otherwise.
I hope there's a rebuild kit for that diaphram if that turns out to be the problem.
I will post my results after Memorial Day.
Thanks for everyone's input.
 
Randy88FJ62 said:
Threeeeyedbandit,
My truck can go into 4Lo by moving the shift lever. The 4WD switch (for 4Hi on the dash) does not need to be selected. 4Lo engages 4WD regardless of switch position on dash.
Click to expand...

Correct, but it isn't a mechanical 4wd selection. The low range switch disconnects the 2wd VSV via the 4wd relay and energizes the 4wd VSV. Disconnect the the low range switch on the tcase, and now you get the option of 2wd low.

Just clarifying how the system works :beer:
 
RECRUISER said:
I am going to use a vacuum pump to apply major vacuum to that diaphragm. If it works and I get vacuum, my solenoid should actuate and I will not be able to turn my driveshaft?
I am going to follow this to its logical conclusion thinking that it is still a vacuum issue until proven otherwise.
I hope there's a rebuild kit for that diaphram if that turns out to be the problem.
I will post my results after Memorial Day.
Thanks for everyone's input.
Click to expand...
Correct! Vacuum on one nipple will engage 4wd and the other will disengage it. Let us know what you discover
 
ThreeEyedBandit said:
Correct, but it isn't a mechanical 4wd selection. The low range switch disconnects the 2wd VSV via the 4wd relay and energizes the 4wd VSV. Disconnect the the low range switch on the tcase, and now you get the option of 2wd low.

Just clarifying how the system works :beer:
Click to expand...
Thanks, I appreciate having the theory of operation.
 
Yes, you are correct ThreeEyedBandit. I was surprised to learn that awhile back since I thought people converting their 62 tcase to manual was silly. Definitely not the most robust system for the outback but good enough for mall crawlers and weekend outings.
 
Once again I've got some great results to report. It was a vacuum problem in my case!
I went out and bought a handheld vacuum tester (Harbor Freight or eBay), put 15 lb on the line at the firewall that goes to the diaphragm by the transfer case that actuates the four-wheel-drive, and my green 4wd indicator illuminated.
Verified four-wheel drive operation and confirmed that the 4wd was fully engaged.
Next I swapped the vacuum line and when I put 15 pounds on the other metal line at the firewall, got in and put the truck in reverse the green light went out.
Then I put my vacuum tester on the manifold itself and confirmed that it was pulling a full 15 pounds of pressure, check.
Since I've confirmed that everything else is working, the vacuum problem points to that the little red module on the firewall, that everyone has identified already in this forum. I will purchase a new one and install and report back to connect the dots on this thread.

Thank you to everyone who has posted and had made this repair / diagnosis possible.
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My Follow up to my repair:
My $23.99 part from eBay came today and it did say AISIN on it, looked good and new, popped it in and now I have working 4WD! This part also had the correct tab on it already, so not only did the wiring harness snap in perfectly, I didn't have to do any modification on the metal tab.

Big thanks to everyone who was so quick to help me out on this problem and share their expertise so unselfishly.​
 
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Alright I've read I think every related comment and post on here about FJ 62 4wd problems and I'm somewhat confused/possibly got it figured out. I just purchased a 1989 FJ 62 from Missouri. Upon purchase I pushed the 4 hi button and light lit up and I verified by driveshaft it was engaged. Now that Im home in Texas I've been playing with it a little more. After locking hubs and putting in 4 high everything works fine but when shifting to 4 low the light goes off and the front end is not engaged. After reading everything on here and inspecting what was going on I swapped the hoses on the VSV's located on the firewall but this is what I have now. Push the button for 4 high. Engages and light is lit. Switched lever from 2 hi to 4 low and the light remains lit and in engaged in 4 wheel drive low. Verified everything by driveshaft, but when I push the 4 high button to off the light goes out and the driveshaft spins freely. My main question is does the 4 high switch have to be pushed for high or low to work? I've read multiple comments on here that it should shift into 4wd low by going from 2hi to 4low on the level and not even touching the 4 high button. I want the system to work correctly and if this is how its supposed to work then great....if not then what might be the problem????
 
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