2001 Tacoma 4wd / ADD issue

Hello, Been an owner of a 2001 tacoma for almost 3 years now and I've had trouble for a while now with my 4wd only wanting to engage intermittently. I started by popping the cap off the rear T-case actuator and cleaning it up hoping that was the problem. After assembly it still operates as intended but the front end is not engaging. I verified this by getting the front end off the ground and I can move the front driveshaft. I opened up the front diff actuator second and cleaned it up and reassembled but no luck after that either. I verified the motor on the front diff actuator was good on a bench, and then picked up an off the shelf actuator to see if maybe the plug was bad but no luck there either.

I'm wondering what else there is that I can check to get this working. I know there is the 4wd control / ecu and maybe the transmission / add relay but I have no idea what I could look at other than that.

Note: I did make sure there were no breaks on the front diff actuator wiring that plugs into it

 

You are on the right track. Common problem on yotas that don't use 4x4 alot/at all (locker too). I have a 2004 that was very temperamental going in and coming out of both. Luckily I didn't have to open anything up. For me, I had to keep playing with it. Driving forward and back, left and right to align the gears. Finally it went. Then just remember to engage the systems periodically when in the dirt, even if you don't need them.
Going a step further for your situation, consider removing the actuator and moving the internal fork by hand (tool, pry bar, ect). Also try splashing gear oil on any moving part you can.
A neighbor had a land cruiser that wouldn't engage the locker, long story short, they didn't move the vehicle left and right while moving forward/reverse to align the gears.
Also, fuses?

Good luck!

 

I've tried playing with it a few months back and it worked for a while, but whats weird is, when I used an off the shelf actuator plugged in not mounted to the truck, it didn't move at all. It's like signal from the rear isn't making it to the front. Either that or power.

The only fuse that I could find to check was the 20amp under the steering column close to the door, and it was fine.

I really love this truck but this issue is starting to get really annoying

 

Are you getting dash light indication or no?

 

I get an indicator on the dash when it is working, but as of now no indicator on dash.

 

Do you have a j-shift or a push button t-case? If you move the lever to the 4lo position, do you always get a dash light and engagement of the front axles?

 

Push button t-case. Haven't tried it in 4lo only 4hi. In 4hi I got no light but t-case functions as it should. Does 4lo work differently than 4hi?

 

Did you try cleaning the electrical connectors on the ADD actuator? Then if you trace the wiring back from there, there should be another connector near your driver side motor mount. Inspect that next connector and consider cleaning the contacts with some QD electrical connector cleaner.

 

I've removed the cap from the ADD actuator, made sure the contacts weren't corroded and checked the pins on the cap, all of which looked clean and fine. The connector looked good as well that goes to it, not dirty or anything. I unplugged the other connector in the drivers wheel well and it looked fine to me, no breaks that I could see and the connector looked clean.

 

So this is a bit confusing. Based on what you wrote earlier, the impression I got was that 4hi functionality was intermittent.

Please clarify. When engaged by the button, 4hi always works but some times the light is not on, even though 4hi is still working to the wheels?

 

Let's start with the shifter. Disconnect the 2-pin plug from the 4wd shifter. With the 4wd button off you should have no continuity between pins 1 and 2. With the 4wd button on there should be continuity. If all checks good I want you to check your 20a 4wd fuse. Report back your findings and we'll go from there.

 

To clarify, When I press the 4wd button, the transfer case actuator does its thing every time, moving the rod on the transfer case. The 4wd light is not coming on the dash, and there is no power to the front wheels. A few months ago when I tried to use the 4wd it worked (everything, light on the dash, t-case actuator, front diff actuator) but it is very inconsistent. Hopefully this clears things up if not I'll try my best to explain.

 

Move the lever to 4lo without pushing the button.

On my push button tcase that'll engage 4lo and turn on the dash light. Curious to see if yours behaves the same way.

 

Button works as you described, continuity when the button is pressed (on), no continuity when in the out position (off). 20a 4wd fuse was fine but I went ahead and replaced it with a new one. Issue persists, if only it was something easy.

 

Here ya go

 

In one of those pdfs it mentions an ADD relay, any idea where that would be? I saw a thread that said behind the glove box, and I pulled it out and looked. Either its not there or i’m overlooking it

 

I believe push button systems dont have an A.D.D. relay but ill double check the diagrams

Edit: The location diagram only shows it for trucks without the push button 4wd selector

 

I'd check that Transfer 4WD position switch. There's a page in the FSM for the appropriate resistance range it should have.

 

The switches are all easy to check. With the switch depressed there should be continuity between the pins. No continuity when depressed.

Edit: just realized I tried helping you out with your 4wd system a little while back lol. Yours was a vacuum issue if I remember correctly?

 

Indeed. Mine was on a '98 4runner and ultimately the actuator just wasn't moving freely enough (I guess) because a handheld vacuum pump worked to engage 4WD once, and after that it engaged/disengaged freely on command as designed. Thanks again for your help with that one.

OP here has electronic A.D.D versus vacuum correct?