*Solved* Another 4wd blinking thread

2010 A/T Toyota Tacoma DBSB 4x4. Rear OEM locker. 139,000 miles roughly. Drive train all stock components. No other related modifications.

• On December 1st I was going to engage 4wd statically (not on-the-fly), large clunk and 4wd never fully engaged. Light remained blinking.
  
• All the steps to take it out of 4wd at the transfer case shift-rod to 2wd (all-the-way in) and sliding the ADD sleeve all the way toward the transfer case for the same I still have engagement issues. Light still blinking.
  
• On drive to Toyota light finally switched off. Toyota quoted both actuators as bad, stating no bad sensors, wiring or ECU. Stating still in 4wd yet only the front driveline still was spinning so the hubs are not locked in. Will check on its current state again tomorrow.
  
• I have replaced both actuators with used working units without any engagement. You can hear both actuators working, but the indicator never becomes fully illuminated.
  
• Tested with ohmmeter but not skilled with one (hence visit to Toyota) so somewhat relying on their opinion for electrical components. Also assuming t-case to ADD actuator is good because of the response in the front actuator. I am assuming bad sensor, ECU or harness despite Toyota’s evaluation.
• All of the fuses checked and battery resets were attempted. Pig tail at front actuator was also replaced for a newer one.
• I am working on sourcing an A/T FJ transfer case around 100k miles in Washington for $200-300 or less lol.
  
• Have checked all related threads on this attempting to fix with the above solutions with clocking mechanism and such. I tried to better interpret ohmmeter readings and all that but still have more to read there I think...

Questions:

• Has anyone replaced the 4wd ECU wiring harness, part #s and or write ups on it?
• I haven’t found a reliable source for the part numbers of the 4wd and 4lo sensors, does anyone also happen to have those?
• How to read current drive train system state in a relatively simple way?
• Let me know if there are any other tips, or questions about my setup or what I have tried so far.

 

Techstream?

 

I'm firmly of the belief that anyone too stupid or lazy to operate a transfer case lever shouldn't own a 4wd in the first place- I think most of us would agree that Toyota should have stayed with a manual transfer case like they did with the FJ Cruiser. Yes, I hate the electronic 4wd system on most trucks and know folks who have had issues with other brands as well.

 

I don’t have one right now, but will probably buy one. Which one did you go with?

 

Operating the shift-rod is how you take it out of 4wd at the transfer case if your t-case actuator isn’t working. Yep the FJ manual t-case is the only true long-term solution to this problem.

 

I think these are the Napa part numbers for the position sensors I found them in one of the other forums somewhere back in time .

84222-12010
84222-35121

 

I also think its totally possible to have unintentionally mistimed/aligned the transfer actuator by doing the shift rod shove. Thats why i do think mine is bad even tho the motor still runs when jumped over with 12vdc direct.

 

thanks I have one bad switch that still has continuity but I am still suspicious of it. I ordered -12010 but I think the correct one is -35121 so will correct that next. From what I have seen for the 4runners and Tundras that run this actuator as long as your worm gear is placed properly your timing will correct itself. https://www.tundras.com/attachments/tundra-transfer-case-timing-docx.387972/As I noted this new t-case actuator has not been split, and I have response from no indication to flashing. Image of old actuator where I pulled the switches from.

 

I haven’t actually.

Any luck ?

 

It’s been raining a crap ton but haven’t made much more progress. I did confirm I can manually drive the ADD and I am still getting a consistent switch-over but never a solid light. I am getting that 4lo indicator that was broken on mine. Although I am not highly confident it will work since it surprises me that it would interfere with successful 2wd/4wd transition. There are some other symptoms like 4lo light will only blink outside of neutral. In neutral it won’t even come on so I want to fix that regardless first. Then I heard the rear differential transfer indicator is the same as t-case so when the rain stops that’s my next step to swap those out.

 

No luck on that sensor. Still won’t go into 4hi or 4lo. Going to try to swap the ADD actuator again as the response from the one I swapped in is actually not is responsive as my existing. I am going to try with the sleeve in mid-position next time and see if that does the trick. I did get response in the ADD arm without it being in the truck so I am thinking the system is just simply out of sync.

 

Mid-position makes no difference. So now I am back to potentially the wiring harness being the cause.

 

Replaced that sensor, re-centered ADD (after solder fix) and replaced the bad t-case actuator. Once I properly timed the t-case actuator to 2wd using the following and making sure the shift rod was in 2wd with proper alignment on the dogs I was good. Test drive is mostly good

4lo does sometimes not fully engage and 2hi will blink with it. Restarting the truck in that case will bring it into 4lo. After that transitions happily again. I did get into the same state once again after letting it sit so hopefully doesn’t work it’s way back into failure again.