4wd System Operation & Help Thread

Yea test light, meter, and something to backprobe with.

Yes if you have something suitable to backprobe the connector with.

Forgive the crude drawing but this would be my setup if I was testing it I would want to check the following when the buzzing is occurring and see what we have:

Test light across power (F13 Pin 5 (Violet)) and ground (F13 Pin 6 (White/Black)) coming into the 4wd ECU.
Test light across F13 Pin 3 (Red) and Pin 4 (Black/White) (ADD Motor Circuit).
Test light across F13 Pin 1 (Blue) and Pin 2 (Green) (Transfer Case Actuator Motor Circuit)

You will need to be very careful to not touch the pins together while testing but this is how I would do it.

 

Perfect
Ill get my supplies and try to do it this weekend.


Let see what happens.


So im assuming i alligator clip one back probe and touch other back probe with tip of the light?

can i put a piece of rubber in between the two probes to make sure they dont touch?
Thanks again

 

Yes, you may need another person to move the switch for you though.
I made several test lights from old light harnesses with banana jacks on them for ease of use.

That would work I guess.
These work well when backprobing is inconvenient, the genuine ones are pricey but the generic ones are relatively inexpensive.
Only note is if you use them on exterior wiring put a dab of liquid tape on the hole in the wire when you are done.

 

Gotcha thanks

 

Hey all sorry i havent reported back.
Im waiting for a friend to help.
The rain here has been a downpour every afternoon and i am out in the open.
Soooooo soon.
I may try and pull the front diff ADD tomorrow A.M. just so i feel like im doing something.
Ill report back

 

Ill right i didnt want to leave ya guys hanging..
I took apart front diff ADD bench tested solder it, it was clean to begin with and no obvious problems.
Welp that wasnt the problem..

To be honest testing those tiny wires freaked me out.

So i decided to check transfer case actuator
BINGO!!
Water inside and corroded electrical.
Frayed breather hose.
Clocked it backed to 2wheel.
Cleaned electrical with green pad and alcohol.
Greased it up with dialectic on electrical and white lithium on gears.
Thanks again for your help.
Im so happy im up and running!!
This thread was my answer!!
Corroded and full of water transfer case actuator

 

This thread is amazing. Want to check for ground on engine (EE) but having trouble locating it. Anyone have clear picture of it on block?

 

I have it in the first post, it's on the rear of the passenger side cylinder head near the coil connector.

 

Hey guys, thanks for the information I believe I have everything that I need to diag. But wanted to ask some questions to see if you know where it would point to. I have an 07 V6 and the hose was broken on the transfer case actuator. I went and replaced that today and my truck seamlessly goes into 4Hi and I can hear everything engage. However, it will not even try to engage 4 lo. I took the actuator off today and everything looked brand new inside and it looked flawless. Any ideas as where to look with this information or to pinpoint why it won’t even try to put it into 4lo(yes I am in neutral since it’s an automatic). I am thinking it could be a bad ground or a bad neutral safety switch but wanted to see if you guys had any ideas

 

Does it beep when attempting to shift to low?

 

It does beep when trying to shift into 4 lo and the light is blinking

 

If it beeps immediately when you try to shift to 4Lo either your speed is above 3mph or the 4wd ECU isn't seeing a neutral signal.

 

I am in neutral with 0 speedI even tried going 1 or 2 mph and putting it in neutral and it beeped right away. How would I check if the 4wd ECU is seeing a neutral signal, and what is the most common fix for this?

 

You need to check F12 Pin 22 (Blue/White), it should be at battery voltage (~12v) with the truck in Neutral and key on.

 

And I should be in 4wd high for this? What if I am getting 12v in neutral? Bad ground from there? And if I’m not getting 12v in neutral, test continuity to the neutral safety switch and if that’s good bad switch?

 

It doesn't matter what mode your in, give me a bit and I'll pull the diagrams for your truck.

 

Thank you I appreciate it

 

I just looked at the 07 diagram, looks like the Neutral Signal wire will be Green/White on yours.

 

I didnt see you mention i may have missed it.
You are in 4 high before trying to shift to 4 lo correct?
And you said you pulled actuator was that the transfer case one?
Just wast sure if you pulled front actuator pr transfer case.

 

Check voltage in neutral and got 0 volts. Going to check continuity of the wire next.