How To Trouble Shoot 4x4 Actuator

From other things I’m reading, if the t case thinks it’s in 2wd or 4 lol the same blinking light/no 4wd problem happens.

 

I have been burying my balls into this and heres a list of what i have checked, confirmed, troubleshooted and diagnosed...

Issue being 4x4 light flashes in 2 hi.
initial issue was 4x4 light started flashing while in 2hi. driving down the highway on a clear drive pavement day.

Testing
front ADD actuator. Removed with minimal fluid loss. Water was found inside the ADD. water removed, motor tested on 12V in both directions, checked OK!
cleaned all connections and gears. continued with continuity text through all the power leads to terminals and internal switch to the plug on the outside of the actuator box. all continuity checks OK
upon reassembly i put the liquid gasket around the mating seal of the cover before reinstalling it.

Transfer case actuator limit switches. removed both 4Hi and 4Lo limit switches, performed continuity test and resistance tests
4Hi limit switch had poor continuity and some resistance throughout the stroke of the switch. replaced the switch (100$ at auto Value) check OK
4Lo limit switch was in good working order throughout the whole switch stroke. check ok

Transfer Case actuator
Pulled the Tcase actuator cover off and ensured that things were clean inside and performed continuity tests similar to the front actuator. all checks out OK

4x4 Module (under passenger side of dash)
Pulled the plugs and performed continuity tests to the front ADD wiring, transfer case, 2hi/4hi/4lo switch and chassis ground.
Performed ground fault test to all the same wires.
This is from the wiring diagram found here
https://www.customtacos.com/tech.ol...toyewd/06toypdf/ewd/2006/tacoma/h/em01d28.pdf

Replaced 4x4 switch. issue continued. performed Diode test on both original and new 4x4 switch and both were functioning as they should be. check OK

While in 2hi, the front drive shaft from trans case is loose and rotates, indicating that the trans case actuator is free and NOT engaged in 4x4 of any sort
(have not yet lifted the front of the vehicle up to ensure that the front diff is not engaged while in 2hi, though there are no indications while cornering that would suggest it is engaged...)

As it currently stands, these are the issues with the function...
start vehicle in 2hi, the 4x4 light flashes, switch to 4hi while driving, light continues to flash, switch to 4lo while driving, light continues to flash with no buzzer
shut off vehicle.
start vehicle in 4hi. light flashes momentarily then i hear the actuators engage and light stays on, traction indication on snow represents that 4x4 is engaged. at this point, switch to neutral, and CAN engage 4lo. at that point i CAN engage diff lock light stays on. i can turn off the diff lock switch, diff lock light flashes and goes off as i hear it disengage. truck to neutral, i turn from 4lo to 4hi. 4lo light goes off as 4x4 light stays on, normal 4hi operation is clear. while in EITHER drive or neutral, I turn to 2hi, i hear the actuators disengage but the light continues to flash for 4x4. vehicle performs as normal 2wd would, slipping and not going anywhere in snow haha.

consensus
all actuators DO work and complete operation while in 4hi
while in 2hi there is some sort of issue or feedback of some sort telling me that either something is not where it should be or that something is wrong in the 4x4 module?
i cannot switch from 2hi to 4hi and have things function but CAN switch from active 4hi to 2hi and have things function.... but.... not complete?

I got my secondary 4x4 module tonight and will be plugging it in either tomorrow or thursday to see what comes of it...

other documents i have found to help are listed...

https://www.customtacos.com/tech.ol.../06toyrm/06toypdf/06rmsrc/rm2006ta/034000.pdf

i think that is everything... any questions please ask, any help please advise, any guns please shoot me hahaha

 

Here's what I did to fix those problems years ago. Swap in FJ transfer case and FJ non-ADD front differential tube, now 4x4 works the first time every time. Sorry can't be much help to your issues but sounds like you've thoroughly exhausted most of the issues aside from replacing the 4x4 module and actuators.

 

I had gone thru water in 4x4. 3 months later switched into 4x4 again and it got stuck. Water got into the transfer case and shorted the T-case actuator. Tried everything and took to various shops. Told me to go to dealer.

$ 3,700 later fixed. Hope its not the case for you.

 

for all you guys that are cracking these things open and finding everything clean inside and bench testing without duplicating the a problem


aside from soldering the points... have you also bent the 3 prongs that ride along that track??

IIRC @jberry813 had this issue a long ways back and his consensus at the time was that bending those prongs was very important, aside from the contact points that needed cleaning and soldering

 

what exactly did they replace at the tune of 3,700??
any chance you have the receipt that shows the parts they swapped?

 

@OverlandTRD Some good info in your post there.

There must be a 2Hi limit switch right? You mention testing the 4Hi and 4Lo switches, but was there a third? Middle of page 4 in the wiring pdf you posted mentions:

Best of luck and let us know how it goes!

 

Having a similar issue .... initially when I went to engage 4x4 the light blinked and did not engage. I checked driveshafts and found t case was engaging and front add was not. Pulled front add and soldered motor and cleaned. Put back together and had 4x4 engaging but front diff would not disengage. I bought a new front add and installed to find same issue where it will engage 4x4 but upon shifting back to 2h the front diff won’t disengage... had dealership diagnose before buying new front add and they said I need new t case which I don’t think is accurate. Any help will greatly appreciated .... to update a bit I’ve found that when shifting from 4h to 2h the front actuator literally beeps continuously

 

My brother in law hooked my truck up to the scanner yesterday. It threw a ton of fault codes. One was the 4lo sensor and the transfer case switch. We’re going to dig a little deeper when he has access to his Toyota software and then we can hopefully go strait to the source before replacing and testing each part by hand. I am going to remove the transfer case actuator and examine it just to be sure it’s not bound up anywhere.

 

So I don’t have mine fully fixed yet but...
As I said, I did all the work to the ADD, and no dice. That lead me to believe that I must have a bad 4Hi position sensor at the t-case.
Talked to a land cruiser guru in Phoenix, and he says the Lexus has the same problem.
Diagnosis and trail fix is simply unplug the sensor wire and jump it with a paper clip or piece of wire.
Long story short, I did it and my 4Hi and Low engage and disengage perfectly. Getting a new position sensor from NAPA tomorrow for the finale.

The sensor wire jumped with a paper clip made the whole thing work

 

Very interesting. Did u do the paper clip then turn ignition on and axtivate 4wd/4lo or what was the exact procedure?
Thanks

 

Yes. Inserted the clip, then ignition on. Operate 4wd switch as normal. With the sensor bypassed though, the 4wd light flashes all the time when in 2wd.

 

Damn just tried it and it didn’t do anything for me.
Glad it worked for you though. Let us know how the new sensor works out.

 

The first time I did it I think I had a bad connection on the paper clip. Make sure it makes good contact

 

I did it a couple times just to make sure. I have some word feeling that it’s one small thing that is keeping the entire system from communicating and it’s keeping something out of sync. I wonder if removing the transfer cas actuator and checking the selector shaft that comes out. See if it can be reset manually? At this point I’m taking stabs in the dark.

 

@uurx They had to pull the T-case out and replace the actuator. Dealer told me it was still not working correctly. Then they told me the front needed to be replaced as well. I checked it and was fine but would not warranty the part if i bought a new one and installed myself risking having to take it back if it still did not work. So i sucked it up and had them do everything. $1,200 plus on labor alone for just the T-case.

 

FIXED!!!!!!!!!!!!!!!!

Got my new position sensor this morning, screwed it in and viola! I have 4wd. Total expense for the actual repair, $27. No need to buy the OEM transfer case sensor. It’s the same part as a 2000 Tacoma reverse light switch (search Rock Auto). There are many versions out there, but here’s the part I used.
Guess I would suggest that if no 4wd, a flashing 4wd light and a front drive shaft that turns. Pull the plug from the 4 hi position sensor and bypass it before going through the pain of pulling the ADD. If it works, replace the sensor - you’ve saved yourself a lot of time. If not, then go to the ADD.

But, as the wise man said...We’ll see. Only tested in the driveway so far. Won’t get to actually use the 4wd until later this afternoon.

Final update. Just got back from the real test drive

 

That’s awesome man! I hope that it is the long term solution to your problem!!! I found a few inexpensive sensors on eBay for under $10. I’m gonna order one up and give it a shot. If it doesn’t work then at least only be out a few bucks

 

Thanks. I was in a hurry, so I paid a bit more at NAPA. Ordered one from Amazon for $13 to throw in the spare parts stash though.