Rear Diff Lock

As I mentioned in my welcome post, the diff lock on the 2006 Taco is not functioning. When I had the diff out and apart the sleeve and fork are free and engage smoothly.

I have seen in other posts that if I remove the actuator and put the truck in 4L, hit the Diff lock switch, the actuator should turn the gear. IF it as I expect does NOT turn, what are the procedures to diagnose it.

I would assume there's a schematic to be able ck the wiring, voltages etc. or, if that checks out then it's probably/possibly a seized actuator? The switch does cause the light to flash red, and the 4 WD works, I can hear that engage with a Ka-chunk.

Thanks in advance, Nick

 

My Diff lock recently engaged, and then refused to disengage. Since then I've pulled the actuator, which is able to then be "actuated" by pressing the button and it seems to rotate fine. It's like it doesn't have enough oomph anymore to slide the sleeve. Manually unlocked it, put actuator it back on, and would not engage.

Luckily it's a couple minute job if you just want to pull it off and see if the actuator is turning. Just need a second person to press the button. Honestly, you can't usually hear the motor in the actuator working when you press the button on your dash. That would at least tell you if their is an electrical or mechanical issue.

 

Might be a dumb question.. but are you rolling forward slightly and turning the steering wheel? You have do kind of a slalom to get the diff side gears to walk a little bit

 

I had it up on stands in park and rolled the driver's side rear wheel which caused the spider gears to rotate. I figured that would allow it to engage. I think I'm going to pull the actuator and see if the gear turns. But thanks for the suggestion.

 

I have a little info about the diff lock circuit here but I haven't done a whole lot of research on it.
It operates similar to the ADD on the front diff.
https://www.tacomaworld.com/threads/4wd-system-operation-help-thread.742420/

 

Thank you Dm93! Thats exactly what I was looking for. Now just have to burrow through it to find the answer.

 

Sometimes you have to drive a short distance before it will engage, or disengage. Not unusual at all. Don't wait until you're stuck to engage.

 

You can shift into 4L and pull the motor, see if it spins should look something like this. If it's not timed correctly that could be your issue, did you make sure the actuator was in the "unlocked" position as well as the sleeve in the "unlocked" (away from diff) position to match upon reassembly?

 

OK, So I took the Rear Diff ADD actuator out, put it in 4L and hit the switch, no movement of the gear. Opened it up and it was not seized. So now I am going to need the pins to the actuator that get energized and their voltages. I understand that it's controlled by a 4WD ECU. I really don't want to mess with that until I see if we are getting voltage to the actuator. I like to work sequentially and work my way back from the problem to the source.

IF I'm getting the proper voltage to the correct pins, then it's the Actuator, if not I will ck the output at the ECU, if I'm getting it there, it's a wiring issue, if not then I suppose it's the ECU.

Although I am a Master Mechanic, I really hate these new rolling computers. They are planned obsolescence!

 

Check the M+ and M- circuits, one should be power and the other ground depending on which way the ECU is commanding the motor.
I can post the diagrams in a bit, I have it in the thread I posted above but that picture isn't great.

 

I believe there are 6 terminals on the wiring harness to the Actuator, is there a diagram for them? (one is blank)

 

The actuator in one of the links shown above is not like the one in this Tacoma, its motor is inside the actuator, ours is attached with 3 screws externally, and the pin configuration is in a rectangular configuration not in a row

 

Best I can do until I get home.
Hope it helps.

 

That's it I'll post up the full diagrame when I have time.

 

Here's the full 4wd/diff lock diagram.

 

Thank you immensely for your help! OK to check this old brain TM 1 (pin 2) and TM 2 (pin 1) should show voltage when the switch is on and in 4L. They just switch polarity to reverse the motor. TL 1 (pin 5) TL 3 (pin 3) TL 2 (pin 6) are just position feedback. Pin 4 blank. Any idea of the voltage? is it 12 vdc? or?

 

Just to be clear, we are not talking about the rear differential actuator any longer?
Correct?

The terminals you are asking about are for the Transfer Actuator on the transfer case.
To save time, I’m going to refer you to the link below. It will answer all your questions.
https://www.tacomaworld.com/threads/4wd-system-operation-help-thread.742420/

FWIW, you are pretty much correct.
Voltages on the TC actuator are 12v DC (battery voltage)

 

I am speaking about the rear Diff actuator. Your Dec 16, 2022 at 12:13 PM post shows a 6 pin plug. That's the one I am referencing. Thats what I want to know how to ck the voltages

 

Then the only thing you can check is the position / Limit switch.
RLY1 and RLY2.

It’s a 5v dc signal.
I haven’t messed with it as much as @Dm93 has.
But here is his chart. It explains it.