4wd not working

I had the same issue. After taking everything apart, greasing up the actuator, soldering the motor and making sure it works, I put it back together . When I turned on my truck the light was still flashing. I ended up driving about 95 miles that day and the light fixed itself . I also scanned the trans module and I had no codes.

Maybe there is a relearning process and you need to drive it a little longer and it’ll reset ? Hopefully everything works out for you.

 

Close, but opposite. 2HI to 4HI shift is transfer case shift first (has the syncro, spins up everything to match speeds) and then ADD shift because the spin up of the drive shaft has matched speeds at the passenger side diff output and the intermediate shaft.

So, it was determined the ADD actuator was the problem, the ADD was pulled and messed with, there is still a problem but a new one. Highest probability the issue now is ADD position feedback. Either it's out of time or missing connection somewhere between actuator and 4wd ecu. It fits best with the current information.

 

You sure?
Per my memory (which sucks) I recall that the ADD operated first and then the transfer actuator (per my work on 2Lo)... (but i am by no means certain)

We can certainly agree, whichever operates first (when changing from 2hi to 4hi), that is the culprit... (and there is no doubt it could still be the ADD if it is second)

 

100% positive. I've videoed it doing 2HI->4HI shifts at speed. And if you work through the process the speeds at the ADD interface cannot be guaranteed to match until the front diff is spun up. That's why there is a syncro in the transfer case. It spins everything up from the speed mismatch to matching speeds. This allows the shifts to then complete.

Deep dive warning: With an open front diff and static front drive shaft (as is typical in 2HI), and while driving in a straight line, the speeds at the two shafts the ADD mates are equal but OPPOSITE. This means the speed mismatch is 2x the speed of one wheel. This is why the transfer case shift and syncro is so critical. It's designed to spin the front driveshaft up from static to ground speed which is therefore spinning up the front ring gear causing the passenger side spider gear to match passenger side wheel speed, allowing a non-syncro ADD mechanism to shift.

 

Makes sense
Know the typical condition is the driveshaft between the front diff and transfer is stationary. Therefore at that moment the ADD would have to overcome double velocity mismatch if the ADD was first. So logically the ADD would have to be second

Logically it's the ADD still as the root cause

 

And is likely the ADD or DL2 signal on the ADD

 

Alright so I know it’s been a while but times have been tough with money covid etc and that but I got around to installing a new front Actuator today and that did not fix my problem. It’s so weird like my truck goes into 4 high but the green 4x4 light on my dash just flashes saying it’s not engaged still. And to disengage out of 4x4 I have to turn the knob to 2wd and shut truck off then turn back on and it will then click and turn off. Also had a mechanic look at it and he was pretty sure it was the front actuator as well but he wasn’t positive. Any ideas
@BigWhiteTRD @ShimStack

 

I didnt reread the thread, and my memory is 'subpar', but I somewhat recall...

At this point, I would say your most effective diagnostic tool will be techstream (dongle and computer program), or an ohmmeter (and somebody who is familiar with using one)....

which one do you want to tackle?

 

I’d like to try to diagnose with ohmmeter I am very familiar with using one as I am an electrician but haven’t worked on much DC stuff.

 

FYI, this is not a 3rd gen transfer case actuator. Looks like you are headed this direction so don’t use this for reference. I just had mine in pieces and successfully reassembled so check my recent thread that i updated with pictures. And good luck, its a pain in the ass.

 

When is the physical engagement/disengagement occurring? If you start the truck right now in 2H, blinking or normal? Then you shift to 4H and it physically engages but the green light blinks like it hasn’t completed engagement? Then you can turn the dial back to 2H and it will physically disengage, but in order to clear the blinking light you have to turn the truck off and back on again?

Trying to understand the flow correctly. I’m not an expert, but I did just go through a slew of issues w/ that transfer case actuator. The good news is you can take it off and reassemble w/ out needing gasket sealer so theres no 24 hour lag time. The bad news is those gears are a bitch to time and get reassembled correctly.

 

So starting the truck in 2hi all good no flashing lights or anything. Then turn knob to 4hi and it clicks and engages but 4hi light just flashes thinking it’s not engaged. Then when I turn knob back to 2hi it does nothing until I turn truck off then back on then I can hear the disengage click and light stops flashing again back to no light.

 

Perfect
Just remember to test your meter before you start, so you know it works...

Most of the data you would need is already posted up, in either the service manual or here
https://www.tacomaworld.com/threads/4wd-actuator-troubleshooting-transfer-case-and-add.578262/

First step would be to take off any skids to access the actuators and their connectors.

I would then ohm out both the ADD and transfer actuator with the truck in 2hi and in 'happy condition'
Disconnect the actuators and check the feedback wiper readings against the tables for 2hi to make sure they all match.
Reconnect the actuators and start the change and produce the 'failure'
Shut off truck, and recheck the actuator feedback wiper readings.

You should have a wiper(s) that doesnt match the table, and will point you to a bad connector/wire/actuator wiper.

@ShimStack and I (I think) both have said it looks like bad signal from the ADD, so focus there first.

If you dont have any incorrect readings, the issue is likely intermittent, or the issue is in the wiring between the actuator and ECU, and will require further diagnosis.

That is my best suggestion to start.

 

okay thanks I’ll try that out when I get sometime this week I did just install a brand new ADD today though so I don’t think it’s that. My bet is transfer case actuator wiper detection switch

 

good luck

It certainly could be a bent pin in EC1, or J14, Etc...
Jump in, see what you learn... and write down the results you are getting...

 

hey is there another spot I can test that transfer case actuator at other then right at it as it’s a pita and can’t see what pins I’m actually testing

 

so the results of the front ADD in 2hi are
Between pin 1 and pin 2= 7ohms
Between pin 6 and pin 3= open
Between Pin 6 and pin 4= Closed(0 ohms)
Between pin 6 and pin 5= open

having trouble getting reading on transfer case actuator due to location and can’t see what pins I’m testing. Wondering where that harness goes to and if I could test else where instead of right at the actuator.
Was able to test between pin1 and pin 2 and got 2.8 ohms

 

I was able to test the transfer case with a hand from a friend. Here are all my results. Although now I’m getting 2wd to 4wd mode change failure shortly after installing the new ADD

To me it looks like it’s still the ADD. Is it possible that it’s out of position going off my results? As I just put a brand new ADD in.

 

Is the truck physically in 2H? Regardless of switch position. Also, is the sleeve from the ADD in the front fully engaged or disengaged? I believe if its fully pushed one direction or another it will error out.

Did you remove the rear actuator at all? And is the transfer case confirmed in 2H as well?

 

transfer case actuator works fine. When in 2wd it’s fine all other sensors in correct readings. When I turn to 4hi I hear the click from the actuator then I get 2wd-4wd change failure so I turned the truck off with it still in 4hi and error. Tested transfer case actuator again and sensor reads it’s in 4hi and all other sensors are correct as well. So pretty much ruled out that it’s not the transfer case actuator and still the ADD. Waiting on BigWhites response for my front add readings that I got. To see what he thinks. im thinking front ADD is not in the correct Position after installing the new one.

but to answer your question it it’s always in 2hi regardless of switch positions no not really as transfer case will go into 4hi but I get mode failure change error.

To answer next question. I believe actuator forks are all the way to passenger side when I installed.

to answer last question No I have not opened up the transfer case actuator just the front ADD as I had water inside it then replaced that one with new ADD