A.D.D. is not working?!?

Hello All! I am new to TW, but not new to Tacomas. I bought a 2002 Taco without testing the 4x4... Stupid me!!! After attempting to go offroad with it I discover that the 4WD is not working. I have narrowed it down to the Automatic Disconnecting Differential. I can tell that the actuator has been replaced, so before I pull that off and test it, I want to test the relay and/or the solenoid first. The problem is, I can't find either!!! The Haynes book is not very helpful with the location of these items, and I have crawled all over/under my Taco looking for them. Any help or suggestions would be greatly appreciated.

 

There is actually a great 4wd diag chart that is used ,the ecu looks at various inputs ie voltage inputs to determine position that is key in diag anyways let me know exactly what u need when I get back to work tomorrow ill hook u up I'll send info via PDF .

 

Well, according to the Haynes Repair Manual, the problem could be the actuator, relay, solenoid, or switch(not necessarily in that order). My truck does not have the switch on the shift lever, it comes out of the top right side of the transfer case, which I have not tested yet. I cannot find the solenoid or the relay. As for the actuator, I can tell that it has been replaced, so I'm guessing...that the previous owner replaced it and when that didn't fix the 4WD they traded it in. Haynes does not show an exact location of these items(keep in mind that Haynes covers years '95 thru '04).
So, a diagram showing any of these items would be a big help... that or any other suggestions.
Thanks!

 

mine was behind the passenger kick panel. 98 tacoma.

 

I lied... haha didnt read your post, I have a pdf to test the actuator at the plug though

 

Sorry took day off pm me your email ill send PDF

 

One way to test it is get under there and undo the clip where the wires connect to the ADD, wait a few minutes, and then connect it back in. If the ADD makes a noise, It is good. If not, then you know that the ADD went out! This diagnose method worked for me when mine went out, not sure if its 100% accurate tho. Good luck!

 

I did find a relay up behind the glove box, but it was a 4 prong relay, and according to Haynes, it is a 5 prong relay that I'm looking for. I did a part number search on that relay that I found, and the part number matched the part number for a headlight relay?!?!? I know that the fuse/relay box in the engine compartment behind the battery also has a headlight relay... But there was not a relay behind the pass. kicker panel.

 

I'm assuming this is done with power to the unit???

 

Yeah. If you have a new ADD or one that you know works and you hook it up and it doesn't make a noise then you'll know that you have a bad solenoid or relay. If it makes a noise like its moving the forks, you'll know the ADD was bad. Heres a pic of the new one I picked up when mine went out.

 

Possibly could be an issue like on the 2nd gens
http://www.tacomaworld.com/forum/2nd-gen-tacomas/263525-how-trouble-shoot-4x4-actuator.html
Poor connection points on the motor inside.