4WD ECU Location

Any resolution on this issue? Having similar problems myself.

 

Had a similar issue--intermittent green flashing and 4lo flashing. When I pulled the connectors for the 4wd ecu one of the female pin "receptacles" had a bunch of green corrosion in it. You could actually see it inside the white connector. I can also make the lights stop flashing by wiggle testing the harness when its plugged in. With the lights out 4wd will work normally. Not saying its your issue but it turned out to be mine...

 

Sorry to revive this old thread, but did you find out the cause to your problem? I’m diagnosing my truck for the same issue but tried checking everything and I’m stuck what else to check.

 

Generally 4WD lights acting all crazy is an ADD problem. If you’ve already taken apart the ADD, cleaned and tested it, then I’d check the transfer case position sensors. There’s two on top of the t-case and bad connection or failures of those will also cause issues. If neither of those are the issue id guess 4WD ecu. Best of luck.

 

I'll have to check the position sensor on the transfer case. I'm still having problems and have very little motivation to work on it.

 

Well we can’t help you with motivation but I’m sure that Tacomaworld can certainly help you figure out what’s wrong with your truck.

 

For my vehicle, it was the transfer case. The 4x4 system was never used by the prior owner.

 

That’s just criminal. That poor truck.

 

My ‘06 Tacoma started having 4WD problem. I ended up disassembling the front diff ADD, reinstalled it just to find out it was the transfer case actuator’s vacuum hose cracked open.

Check wiring and hoses connections first before disassembling any parts saves you a lot of headaches.

 

Hey guys, fun fact, third gen Tacomas have the same issue! Thanks Toyota!! And thanks TW for the knowledge on how to fix it lol

 

Appreciate the info here. Replaced my actuator 2 years ago and had worked fine since then. However, over the weekend when I tried, its just flashing 4LO again. After a few reattempts by restarting it is working properly again, but going to look into the ecu to see if there is corrosion there like stated above that causes intermittent failure. I notice when there is no click there is no 4wd and 4LO flashes.

 

Mine goes into 4hi but light in dash blinks

 

https://www.tacomaworld.com/threads/4wd-system-operation-help-thread.742420/