Blue_petersen77

Don't know anything about a click or clank but then, mine functions properly. Always make sure you keep the drive shaft greased up though. Once I felt it kinda wanting to pull sluggishly in 4l then greased everything and the problem was gone.

BeenYota

Went home on lunch and decided to check it out (12:12pm-cst). After removing my skid plate and draining what I could from the front diff, I removed the 4 bolts and separated the shift fork to find the shaft was out of position. I have used a hose clamp to keep this from happening and after buttoning everything back up, I decided to drive across the lake back to work and 4WD is back in business. (1:15pm-cst) Thanks for the help.

tried4x2signN

Been... Do you have manual locking hubs?

BeenYota

Warn premium manual locking hubs to be specific

bigroy408

http://www.4x4wire.com/toyota/tech/add/

graduatedpine

Very informative

banoobee17

yea i have a problem with my 4wd too bigroy408 i know what you mean mines does the same thing it clicks to let me know its engaging my problems is my 4wd light on the dash comes on and it also feels like i am in 4H and 4L but my fron drive shaft aint doin a thing i tried manual switching the vacuum lines its work but i dont want to have to do that all time so i am stuck PLEASE HELP.

bigtrucknwheels

know what I did to mine? I just hooked up constant vacuum. I didn't see a dip in fuel economy and I never had to worry about it again lol

BeenYota

What vacuum? Oh.. You still running automatic hubs? If so, check for splits in your vacuum hose. If no leaks; take a voltmeter to the valves and repair or replace if necessary.

If running ml hubs; read the article in the previous post and remove the vacuum and lock the tube.

Respectfully,

bigroy408

Yeah I tried to make the 4wd to work but i couldnt even get the 4wd light to go on the dash....I am just going to get the manual lock hubs when i could get some money....sorry about that. hopefully these help:
http://www.4x4wire.com/toyota/tech/add/

http://www.offroad.com/trucks4x4/art....jsp?id=399612

BeenYota

Bigroy-

You'll be glad you did and either way you can always do the less expensive stuff without $ as long as you have a little time. The first thing you could check is to see if the plug at your front diff has continuity. I've had to splice and crimp this 2 pin connector multiple times and have since run new/longer/heavier gauge wire with a better route to prevent damage. It's easy for these wires to get severed. Otherwise you can still check at the relay. Let me know what you end up doing and if you need any help along the way.

Best,

1993hiluxsr5

Hi , i had a 1993 hilux with the same problem, it turned out to be the transfer box actuator not engaging the front driveshaft, so although the a.d.d was working it had no 4wd but the light was on, so give your actuator a check, worked for me.
hope this helps
p.s. even if it sounds like its working, it might not be !! mine sounded like it was working perfectly but it was jammed, 20 mins and it was fixed

BeenYota

1993hiluxsr5,

This appears to be most common. For those who dont know, what specifically did you do in that 20 minutes to fix it?

Thanks,

89yotarollaGTS

my truck having this issue as well, 4wd took awhile to engage then finally quit all together.. 93 with ADD lol

dutchboy

http://www.4x4wire.com/toyota/tech/add/

The very last paragraph from the above linked article : "Eliminating the ADD system works with either the ADD hub flanges or manual hubs".

It appears that locking the tubes can be done for either hubs (ml or add hub flanges).
Right now I'm going through the same problem and after the article,I'm quite sure I want to eliminate the ADD. With the help of my mechanic friend,we have a question.
Could we just run the vsv vacuum lines together through a manual valve?
To engage 4 wheel drive,close one knob open the other...supplying front diff. with vac. To disengage,close opened valve and open the closed one to release vac. Could this actually work? (of course your lil dash light wont come on,but who needs it when you know your locking it in?)

My rig's problem through process of elimination is the front most vsv isn't getting juice,thus not locking it in. We tried the relay and it appears to be good.
The big question...in the FSM,(and aldata) the diagram shows the vsv wires leading to the relay,then from the relay to a "FUSE". Please...for the love of all mankind...where is this dang dong diggity fuse? We've searched all fuse junctions and see nothing indicating an a.d.d relay fuse.
Could someone also help with wire colors from the vsv to the relay?
I was considering rewiring a committed line to a toggle switch. Question their is...is that fees-able? Or would the vsv not work like that?

keasa1214

sounds like the actuator in the diff. they freeze up if not used a lot.

dutchboy

Actuator is working. Had truck up on stands,checked vac. at actuator and at vsv's. All working. Supplied vac through vsv's and front diff. locks and unlocks with dash light working as well. So actuator is deff. working and like I had said...we have determined that the front most vsv is not getting any positive current. Trying to find out why not. Found the relay for the a.d.d.,but can't tell if it's working properly or not. trying to locate the a.d.d. relay fuse...

dutchboy

Doeas anyone wanna chime in on this? having a real hard time locating "4 wheel drive fuse". FSM says their is one,but does not say where it's at. I checked all 3 clusters and nothing. Found the a.d.d. relay and it supposed to lead to fuse,but so far...nothing.
Any help at all?