2005 Tacoma 4WD lights flashing

Hey everyone, I’m have a weird issue with my 05 Tacoma. The 4WD and 4Lo lights are flashing , and of course no 4WD , no other lights are on except for airbag light. With that said , I have a snap on scanner , and when I connect the scanner to the OBD port , lights quit and 4WD works as designed. Anyone ever come across anything like this?

 

Pretty sure for 4Lo you need to be in Neutral, and 4Hi need to be at a very low speed - I assume you've already met those requirements?

 

Hey bud , yea the 4wD works fine as long as my snap on scanner is plugged in. As soon as I disconnect the scanner from the data link connector , both 4WD lights start flashing .

 

Lots of info on actuators at:
https://www.tacomaworld.com/threads/how-to-trouble-shoot-4x4-actuator.263525/page-29#post-21121963
Scanner impact may or may not mean anything.

 

Awesome I’ll take a look , thanks for the link ! Much appreciated .

 

I just had the same thing once on my 05. Prior to the problem, I had not engaged the 4wd in over a year. I played with it for about 15 minutes, and was completely frustrated. I went under the truck just to look around, and decided to tap on the transfer case actuator lightly with a wrench. I have no idea if that really loosened something up or not, but when I got back in my truck it worked immediately and has worked ever since. It wouldn't cost you anything to try it, but I am certainly not saying it will fix your truck either.

 

Yea tried that Opie In. I was looking for a common denominator between the data link connector and 4WD system , and I don’t see one . I’m going to take another look at the transfer case actuator again when I get home today . Just doesn’t make sense that the system works and lights go out when hook up the scanner ? But like muddog said , might not be related. But something is making it work ???? Frustrating as *%*%.

 

Sounds like your Snap-On scanner is providing a missing ground. Time to check the 4WD wiring diagrams...

 

Hey Blu92, yea that was my exact thought as well , I checked the grounds and I have the wiring schematic on my phone , grounds look ok , I didn’t see anything , however I haven’t ran a ground wire to ground to make sure. I plugged in a known goood 4WD module and that didn’t change anything . But yea the scanner is completing a circuit or ground some how .

 

So reading a little more , the ECU electrically shifts depending on two things , the vehicle speed and park neutral switch. I know the vehicle speed parameters are correct , I read each on my scanner while someone else was driving , cough cough , so I’ll check the park neutral signal at the 4WD module this afternoon . I’ll let everybody know if that’s the problem.

 

Blu92 you were right , I’ve narrowed it down to bad ground or broken ground wire in the body ground wiring . I grounded pin 5 on the diagnostic connector which is part of the body ground and the 4WD works fine .