4wd Lights Flashing???

Hello Everyone!

I am not a mechanic and I don't know much a lot about vehicles but I am a quick learner and I need your guys help to fix my 4wd.

My 4wd Lights is flashing when I try to put it in 4hi but I know the the 4wd is engaged because I jacked up the truck and both the front wheels spin. And when I turn the dial back to 2wd it doesn't disengage unless I turn off the truck and turn it back on. (I can hear the front diff switch to 2wd when I turn my truck back on).

I read a lot of forums about Tacomas 4wd problems and most talks about the actuators. So I took apart the front actuator and it looked fine and it seems to work and I also sodered the pins to beef it up. I also took apart the transfer case actuator and it was clean and looked like there isn't any problems. So I'm assuming the actuators are working because it does engage into 4hi. I also checked the transfer case switch indicators and they both work fine. So is the problem an electrical issue? Is it not detecting that its in 4wd?

What do I need to do to check if it's an electrical problem? I don't know how to diagnose electrical or connectors on vehicles so can someone tell me a step by step procedure.

 

The little toggle switches tell the truck what state its in.

If the truck is physically in 4Hi but blinking, Id think its an issue with the ADD. If the ADD is NOT engaged, then it should be an issue with the T-case actuator.

You can test by jacking up the front, chock the rear. Have a buddy hold the drivers tire still while you try to spin the pass. If everything is engaged then pass side wheel will be locked to the rest of the drivetrain. Trying to turn the passenger tire will turn everything else (including the rear wheels). If the ADD is not engaged, the pass tire will be free to spin.

If you carefully pop the black cover off the limit switch you can take a look inside and make sure the tiny little contacts are clean

 

Is that the switch to send the signal to the 4wd ECU that its in 4wd?

 

Before I take that apart again (cause I put the actuator back on the diff). Is there a way to check if its sending a signal while its on the truck? Like what tool do I need and what pins do I check?

 

I's not clear to me on the diagram how the ADD limit switches work, @6 gearT444E probably could tell you.

 

That pic is of the switch in the ADD. Believe it is technically called a detection switch (earlier I called it a limit switch). If I recall correctly the limit switches are actually the metal traces you see in the plastic case. So those could also be an issue.

You can see in my pic that ADD got water in it, which led to corrosion and wear on the traces. If it were bad enough then I guess that could be your issue, but personally I would lean toward the little black/grey switches first. The contacts in there are super fragile.

Anyway, pin 26 on connector F13 at the 4WD ECU should be the feed back from the ADD detection switch. You could probe that if you wanted to. If Im reading it right continuity through 26 to a known good ground should indicate the switch is made (ADD is fully engaged). If the circuit reads open then its not fully actuated or faulty.

Hopefully someone else can confirm what Im saying is correct and I have the right pin #

 

So I just seen this thread and I did the test and I'm not sure if I did it correct. I used a ohmeter and I don't really know how that works. But I put it on the beeping setting.

When I tested on 2wd. Pin 6 to Pin 4 it beeped and Pin 5/3 to Pin 4 didn't beeped. So I'm assuming thats how you test it according to picture. Let me know if I did or did not do it right.

Anyways, so when I tried to test it while the 4wd dial is on 4hi. Pin 6 to Pin 4 did not beep, Pin 5 to Pin 4 beeped, and *Pin 3 to Pin 4 did not beep* so I think that the Pin 3 to Pin 4 is supposed to beep according to the picture right?

So if that's the problem, what does the Pin 3 lead to inside the actuator?

 

He does.
https://www.tacomaworld.com/posts/26085475

 

TnShooter thanks for the reply but were talking about the Front Diff ADD Actuator

 

I think that might be floating around on this site somewhere.
I’ll see what I can find later.

 

Please, thank you TnShooter!

 

Here is post I did on the system awhile back. If you read through the links.
It may be there. I really do need to update it. There’s been a lot of good information since I made that post.
https://www.tacomaworld.com/threads/4wd-system-help-and-information.696298/

System info is here. But you need to know how to read diagrams.

See post # 15 here
https://www.tacomaworld.com/threads...er-to-transfer-case-or-diff-actuators.695818/

And 10 here
https://www.tacomaworld.com/threads/4x4-problem-i-cant-resolve.575092/#post-19056025