4wd System Operation & Help Thread

Are you sure one isn't bent back so that it's not properly contacting the traces on the plate?

 

yes sir 100% Ichecked the ohms in each position

 

Did you check if TL2 is still not reading correctly or if something changed?

 

Its like the motor won't run long enough to swap from 2h to 4h, which is the longest travel for the shift motor, as I stated earlier, if I time it in 4h it will shift to 4l and back to 4h with no issue. It just wont shift from 4h to 2h or vise versa.

 

Well the limit switches (TL1, TL2, & TL3) tell it the position of the motor and when to stop it so when there's a problem with them it doesn't know where it's at.
According to your previous testing TL2 wasn't correctly switching to 0v in 4H and the transfer case shift has to complete before it will shift the ADD, that's why I asked if it was still the case that TL2 isn't switching.

 

I you switch from 2h to 4h, no, it doesnt go to 0v. the motor stops about half way between 2h and 4h, on the limit switches, it does actually lock the tc in 4h though

 

Well the wiring checks good and it shifts to low so it can't really be anything other than an issue in the actuator or a terminal fitment issue in the connector.

As you can see from the picture TL2 should close as soon as the actuator moves off the 2H position and not open again until it reaches the 4L position.

 

ok,I will try it again

 

Good day everyone, as far as your ADD not engaging and the indicator light flashes along with the beeping sound 9 out of 10 times your problem is in the ADD itself. All electronics work and spec out like the cart says. The problem lies with the manufactures spot welds on the motor of the ADD. Remove the ADD and remove the cover, carefully resolder the connectors on the cover to the motor and reassemble. Be careful not turn over the main body or the gears can fall out. I resolder my ADD in 2020 after replacing it 3 times and have not had a problem since. Also, if you do any decent water crossing it is recommended to extend your vent/breather tubes to the highest location possible, so you don't get water into your ADD, Transfer Case or Rear Differential, causing damage to these components can be costly.

 

reordered a new tc shift motor and it fixed the problem! thanks for all the help

 

Hello people of Tacoma world
So I’m having some ADD problems I guess. I did the continuity test and it came back with DL1, DL2, and ADD as incorrect voltages.

In 4H:
DL1: expected 12v actual 0v
DL2: expected 0v actual 12v
ADD: expected 0v actual 12v

So… now that I have this information where do I go next? I know DL1/2 point to ADD limit switches. Obviously ADD points to ADD. Do I need to replace the ADD? I removed the ADD itself and inspected it, looked brand new inside, all contacts are contacting!

 

Are TL1, TL2, TL3, and 4WD correct?

 

Yes, everything was correct besides DL1/2 and ADD

 

Timely reminder to check and exercise the 4x4 components on your truck frequently to keep them happy and working. I realized today I hadn't done so in a while (thinking early March?) so turned the switch to 4H in the driveway after running a few errands: blinking light: no engagement. After a few tries, moved the truck forward and back about 10 feet: no change. Back to 2H: blinking light out. Took it for a ride on a long straight-away: no go: 4H: blinking light. Of course no 4L to try unless 4H is working first. 4H finally engaged consistently after about 10 tries, then 4L as well. Like butter now: All good with the familiar "ticks" from the ECU and the happy "klunk" from the front linkage as it engages. Life is good.

I have a reminder on my phone now for a once-per-week test. Don't neglect the vintage 2nd gen 4x4 system: especially on an 11 year-old truck.

 

I'm making sure because the 4wd ECU will not move the ADD until the Transfer Case Actuator has completed it's shift.
Did you test the ADD motor while you had it apart?

 

Make sure to check those vent hoses as well and also the ADD vent hose is positioned near a power steering line clamp that has the potential to rub a hole in it.
https://www.tacomaworld.com/threads/4wd-system-operation-help-thread.742420/page-17#post-28163684

 

No. That probably would have been a good idea though… it the gears moved smoothly but I didn’t test it electronically. It looked brand new but the truck does have 201k miles on it

 

The motors themselves usually don't fail but occasionally the spot welds on the terminals crack and lose connection.


The only way to check for power there is to backprobe Pin 1 (Red) and Pin 2 (Black/White) and watch the meter/test light while you attempt a shift.
Not too easy to do where it's at.

I guess you could backprobe DM1 and DM2 at the 4wd ECU and do the same thing, that would tell you if it's sending power out but wouldn't tell you if it's making it to the ADD or not.

 

Thank you for the head's up reminder on the vent hoses. I'll crawl under there tomorrow and carefully look them over. It has been a while since the last time I checked them, as there has never been an issue with them completing the sequence. The glitch exercising the actuators caught me off-guard today after nearly four years of flawless service.

 

I could try and give that a shot. At the end of my pay grade with electronics here though. Theoretically, could I remove the ADD but leave it plugged in, try and shift into 4H and see if the arm moves? Or is that an utterly terrible idea that will render my truck useless