Clicking/Sucking when disengage/engaging 4H

Hey guys,

My transfercase is full, my drive shaft zerks are greased. I haven't driving the Tacoma in a week or so, just took her out to the trail and she was making an audible electrical click (like a relay) under the passenger side floor when engaging and disengaging 4H to 2H, and 2H to 4H, nothing on 4L.

There's also an audible swoosh or sucking sound underneath the carriage, near the T-case. I haven't gotten under to watch it move cause I'm alone.

Anyone had this before?

 

That's the ADD Actuator for front differential.

 

Good catch @Black DOG Lila

The ADD actuator has been going haywire while in idle and driving around. I'll see if I can replace the motor or clean it up without a full replacement let y'all know how it goes.

At the moment I'm engaging into 4x4 fine, just got a sound with it.

 

I would be surprised is it’s a vacuum actuator on a 2001, so I can’t explain the swoosh/suction sound. The clicking is a relay under the passenger kick panel.

 

I have a J-Shifter. Good to know on the vaccum diaphragm/lines. Looks like I've got some reading ahead of me

 

Does the 4wd shift knob have a 4wd button on it ?

 

No sir there is no button, manual shifter like the lower one in bar master's first photo here: https://www.tacomaworld.com/threads/j-shift-vs-pushbutton-4wd-shifter.521362/

 

Shifters

 

I have the same arrangement. Electrical, not vacuum, actuator in my truck.

 

FYI, came across this while looking for a picture of the sleeve in the diff:
Front diff 4wd actuator

 

Looking like in going to have to pull the ADD off and see if it's salvageable with some cleaning and soldering. I've got some transaxle FIPG in the garage already sitting around.

Ran the tests on the relay and it's functioning 100%.

Running tests on the ADD connection and it checked out in H2 but once in H4 the continuity was wrong.

1-3 - FSM Continuity - Mine No Continuity
1-4 - FSM No Continuity - Mine No Continuity
3-5 - FSM No Continuity - Mine 0.01 ohms
4-5 - FSM No Continuity - Mine 0.04 ohms

Its a bummer cause I wanted to wheel up onto a ridge near by tonight to watch the fire works but I don't want to get stuck in H4. HOPEFULLY I 2H will work for me this week at work for now.

A new Yota A.D.D. is going for 350.00 right now and the ASIN's are out of stock.

 

The sounds it's making:
https://streamable.com/huh0kk

 

That's the ADD Actuator servo motor engaging the front differential. Only does this when shifting 2H to 4H and back. Differential stays engaged when shifting 4H to 4L
https://www.tacomaworld.com/threads...n-disengage-engaging-4h.769415/#post-27472519

 

Is it typically this loud? I never noticed it being this loud before. Also checking the ADD connectors continuity today when engaged into 4H it wasn't matching the FSM test/settings.

 

Well I ordered a new actuator to have as backup just in case I wasn't able to resolder and repair my original, but I guess www.Toyotapartsdeal.com doesn't allow returns on electrical parts

So I'm just putting the new one on. I'll try and refurbish the old one but I doubt I'll be able to sell it.

 

Bloody f@#$ hell that was the most difficult thing to put back on I've ever experienced. It beats the AC compressor. This comment by @ToyRyd04 on this post helped: https://www.tacomaworld.com/posts/13178469

Although this part, the Hex socket for the rear diff mount cushion is a 12mm

"-completely remove the lower bolt on the rear diff mount cusion. (On the same crossmember the rack &pinion is attached to, believe it's an Allen key 8 or 10mm bolt" -toyryd04

None of the local hardware stores had a 12mm hex so I had my homie come over which was good cause we were able to jimmy the diff up and down and get the actuator in there. We applied the FIPG once we had it nearly in place and I hope it seals good.

The sound is gone and 4x4 working just fine!

 

Nice! I remember back in the IFS days, that diff is in there so damn tight next to the bellhousing and then to get to the ADD is even tighter.