4wd System Operation & Help Thread

Thanks I have that guide as well, the file I have attached to the first post is the same as Tacoma section of it.

 

I pinned the ecu today and I’m pulling 7V on TL1, and 1.7V at 2-H, lo is 1.17V when switch is in 2wd

 

Interesting those voltages are way out of spec, TL1 (pin B25 Blue/Yellow) and 2-4 (pin A8 Grey) should be 0v in 2wd and LO (pin A15 Blue) should be 12v with the switch in 2wd.
I'm thinking main power or ground problem possibly, what voltage do you have on IG (pin A5 Violet) and Gnd (pin A6 White/Black) at the 4wd ECU with your meter ground connected to battery negative?

 

I wasn’t able to reach battery ground but I used a .5ohm frame ground that my leads can reach

 

Did you check voltages on the IG and GND wires at the ECU?

 

I tested most of the pins I have a picture of the voltage readouts

 

I'd wana check Pin 4 (White/Black) at the Transfer Case Actuator since your showing 7v on TL1, if you have 7v there the ground wire is bad somewhere between there and ground point EE.
Also the wire you have labeled grey did you mean that to be GND wire or the Grey wire?

 

I wasn’t fully sure which wire the list was referring to so I used the smaller plugs grey wire a8 but I’m sure that wasn’t the right one I’m color blind so it’s been a challenge lol

 

There's only 1 solid grey wire, it's the 2-4 signal wire from the mode select switch that is what the list was referring to.
I'd want to see what the voltage is on the Ground (GND Pin A6 White/Black) and Ignition (IG Pin A5 Violet)

Oh yea I can see where that would make things more difficult.

 

I’ll get those numbers early tomorrow morning

 

Ok hopefully we can get this issue nailed down but it's really starting to look like a bad ground to me, are there any other functions of the truck that aren't working properly?
Srry I don't get much time during the day to respond, at night is about the only time I have time to sit down and look things over and all my diagrams and info are on my PC.

 

I really appreciate the help, everything else about the truck works perfectly only thing giving me issues is my 4wd ever sense I did my clutch back in early 2020

 

Did you double check that there is no pinched wiring and the grounds are all connected properly?

 

So I compared the photo on the 1st page to my truck and they look very different but I pinned out the black and white wire, white and black wire and the lighter purple wire on the plug with the pin in it, that’s also where I got my grey wire reading from. But regardless voltages are still very off. Black and white stripe was 9.5v, white with black was 1.7, violet was 11.9

 

DM93 is much better at this than I. But you probably need to check your Grounds.

The Black/White wire is DM2. It goes to the ADD actuator motor on the front differential. The only time this should have power is when the 4WD ECU is UNLOCKING the ADD. It’s as if your ADD is trying to unlock. But I believe it should be battery voltage. Not 9.5

The Violet wire is the main power wire to the 4WD ECU. It should read battery voltage. (Which looks like your battery was a bit low at the time you were testing.)

The White/Black wire is the the main Ground for the 4WD ECU. There should be 0 voltage on this wire. You are showing 1.7v. This needs to be investigated further.

 

If either of the actuators are out of timing would that be something that could be causing the readings to be weird?

 

If they were, I don’t think that would cause the strange voltages you are showing.
And the Ground wire is total separate from the actuator. Timing being off wouldn’t cause your problem here. You have 1.7v on that wire.

 

Good point, I’ll go ahead and make sure that ground is tight and reading low resistance, I work on 24v primarily on heavy equipment so I’m not sure what an acceptable resistance level would normally look like, I’m thinking no less more than 2ohms at the ground would be where it needs to be, if anything I’ll just post my reading here

 

Your ECU connector will have 5 less wires because you don't have a locking rear diff.
1.7V on the ECU ground is concerning, the ground point for it is behind the right kick panel.
Did you get a chance to check voltage on the ground wire (Pin 4 White/Black) at the actuators?

 

He said it had 9.5v? Weird?