Hello everybody -- still having 4WD problems engaging.

I made a post last week about my transfer case probably being dead.

Now I jumped the rear transfer case actuator and the front drive shaft IS spinning. HOWEVER now the FRONT actuator also appears to be stuck and wont engage.

My question is...do I jump the front actuator the same way as the rear? Place power on pins 2 and 3 (its the same style connector 6 pin)?

Also, once I actually manually engage my front actuator and my rear actuator....where do I go from there? What if I do that and then still my 4WD isn't engaging by a push of a button?

I already replaced the 2 switches on the rear of the transfer case and the 2 sensors on top top of the transfer case. The 01-02s do not have a front diff switch either.

If you look at this: http://tacoma.site40.net/4Runner_96-...24ssy/loca.pdf

I already replaced:
No #1 4WD POSITION SWITCH (rear)
No #2 4WD POSITION SWITCH (rear)
L4 Position Switch (top)
Neutral Position Switch (top)

The only one I did NOT replace yet on the transfer case is the Central Diff. Locking Switch (top, passenger side).

I noticed in the diagram there is also a A.D.D switch on the front diff, I am not sure what this one controls or does yet.

Lets say I can "manually jump" my rear transfer case actuator and my front actuator and get into 4WD successfully. But when I press the button nothing happens beside the lights on the dash blink -- where do I go from there?

Just for reference this is a 2001 4Runner with multi-mode.

Any help is greatly appreciated, thanks!

Your "jumping" to conclusions. The front axle actuator is controlled by 2 vacuum switching valves, 1 to lock and 1 to unlock. If the lock VSV isn't doing it's job, the axle won't lock and the ADD switch in your diagram won't close, lighting the 4WD light on the dash. That's all that ADD switch does, verify the axle locked and light the dash light.
More than likely the problem is with the VSV, either the vac line to it or the diaphragm in it is bad, so the axle won't lock.

He has an '01. '01-'02 have the electrically controlled front actuator and no VSV at all.

To force the actuator to engage, apply 12v to the light green wire from the 4wd ecu to the ADD actuator, either at T10 on the 4wd ecu or T6 of the ADD. Reverse out by applying 12V+ to the green wire with white stripe, either at T23 of the ecu or T2 of the ADD.

http://tacoma.site40.net/4Runner_96-...mci/0394wd.pdf

Correct, no VSVs here, all electrical.

I will try to jump the front actuator today and see if I can get fully locked into 4WD.

If that works, I should be able to press the button to get out of 4WD correct? I am beginning to worry if that doesn't work then both actuators need to be fixed!

Thanks.

D'oh !!

I will be tackling this again tomorrow (Saturday) now that we will have some nice weather.

I am going to start by manually engaging the rear actuator, and then the front actuator and see if I can get my 4WD fully locked in manually. Once I figure out if I can do that or not I will then go from there.

Anybody who has tips / suggestions they are greatly appreciated.

Thanks to TheDurk, Slingtoe and Doc2012 so far for providing lots of help. I am determined to get this fixed. It is a mint 2001 sport edition and we have a lift that is WAITING to get installed if we can ever fix this damn 4WD problem haha.

Will report back tomorrow with anything I find.

Update:

Jumped rear actuator.
Front driveshaft spins while moving.
Jumped front actuator.
Confirmed hearing front actuator move.
Lights on dash blinking and still no 4WD.

What do I do next? 4WD ecu? To clarify, when I press the "awd" button on my shifter thr lights blink but the rear doesnt even engage. Could this be the 4wd ecu? I can jump the rear manually everytime no problem.

Sounds more like a problem in the front actuator or the diff itself. If you can hear it try to engage, the 4wd ecu is sending the signal, but the actuator can't get the ADD to engage causing the Detection switch to close and turn on the light.

Are you saying when you push the button, NEITHER front nor rear wheels spin?? The truck just sits there?

I can hear the front actuator moving when I jump it manually with pins 2 and 6.

When I push the button without ANY manual jumping the lights blink but nothing engages at all, I still have normal 2WD as normal but the rear actuator doesn't even engage so the front driveshaft doesn't even spin.

Basically clicking the 4WD button doesn't do anything which led me to believe it was a switch problem but I already replaced:

No #1 4WD POSITION SWITCH (rear)
No #2 4WD POSITION SWITCH (rear)
L4 Position Switch (top)
Neutral Position Switch (top)

I am STUMPED. I think I might bring it to Toyota and give them a list of things I have already tried and let them diagnose it themselves as I am running out of ideas.

Thanks Durk for the continued help.

Silly question but did you test the 4wd enable button on the gear selector itself ?

I see that in the manual to test first, however I just thought that because when I clicked it and it made the lights on the dash blink then it was OK. Is this incorrect?

Edit: Also shifting to 4 Low makes the dash lights blink too but no 4WD either.

Uhhh, forgive me, but nowhere do I see that you checked the 20A 4WD fuse. I'd try a known good fuse from another circuit. DO NOT rely on looking at it. The light is no proof of good 4WD fuse as that light gets its power from the GAUGE fuse. That would certainly fit your symptoms. Then go ahead and confirm 12V+ at Terminal 12 and ground at Terminal 25 of the 4WD ECU.

Failing that, there is no choice but to trace the circuits as described in the System Outline section of the EWD I posted above, concentrating first on whether all the signals are reaching the 4WD ECU. Then see if the ECU outputs the correct signals in return. It could, of course, be the ECU and this is how you tell. The first step is above. I can take you through this step-by-step if you want.

Sorry, but I would never have changed any of the things you did without having shown them bad by intelligent troubleshooting. It's just the wrong way to go about this.

Finally, the ADD switch is a Position Detection switch and tells the 4WD ECU that ADD successfully engaged and it is ok to turn on the light.

Yes I did check the fuse, first thing I did.

I was fixing the switches because of the yotatech thread (4WD won't disengage on 99 4Runner LTD - YotaTech Forums) where it solved 99% of peoples 4WD problems (either for engaging or disengaging) and I didn't spend a dime on them. If you hook power up to the switches and then cycle them a few times with your thumb you can make them work perfectly again for free! I had 3 bad switches, and then once I did that they all read perfect after this!

I will swap the fuse first and test that as yeah even though it looks good, can never be sure. I will then test if the 4WD ECU is getting the correct signals.

Thanks!

I just ran into this problem last week, except I have a 99 limited with e locker. I used 4wd pretty regularly when i went in areas where i thought it was needed or to control the truck more. I was at the beachn drove though some sand as i was exiting it started to dig so i hit the 4wd push button an the lights keep blinking as far as im aware but it went into 4wd cuz it got out of the sand. The lights had started to blink randomly when the button was never pushed and last weekend it engaged at about 50 mph which sounded terrible!I was able to push the button a few times and it came out of 4wd but now it doesnt do anything and only the pass. side rear tire spins?? I was trying to crawl up a little rock n the front yard changing through the gears, first they were all moving, then 2nd try only 1 tire??

Semi-necro bump here but can somebody answer me the following question:

If I can jump my rear actuator with 12v and get the front driveshaft spinning does this verify that my transfer case is OK?

If this is the case then I am beginning to believe that its actually my front actuator that is indeed the culprit. As once I have the front driveshaft spinning, I go to jump the front actuator and I can "hear" something move / working however it never locks me into 4WD.

Thank you everybody.