4wd System Operation & Help Thread

I will do the readings with both add and tc motor disconnected give me a few

 

New readings

add and tc motor connectors off

 

If i cycle key on off i can get it to get out of 2hi/4hi but light will blink. Have confirmed add locking up/unlocking

 

It really looks like you have an issue in the Transfer Case Actuator as well as something going on with the wires going to the ADD Actuator or something goofy is going on inside the 4wd ECU with the voltages being out of whack.

I think unplug the actuators and 4wd ECU and check resistance between the limit switch circuits and ground so we can rule out shorted wires.

Also maybe pop the ECU apart and see if there's anything that looks suspicious in there.

 

I need to go buy a better multi meter i was using a test light with v reading

 

Ah that's why we may be seeing skewed voltages, that makes sense.

The test lights with voltmeters draw a fair bit of current, they don't work well to test sense circuits.

 

Gotcha, also my battery could be running a little low, which is why volts are lil higher when truck is on and i test.

now idk what to do im at a loss.

 

The battery is fully charged at 12.6v
With the truck running it will be 13-13.5v (supplied by the alternator)

 

Ahhh ok nvm then. Could it be tc actuator?

 

It looks like a problem with the Transfer Case Actuator but we need to get a proper meter to test with, I believe the test light meter is pulling the voltages down and skewing the results.

Was the vent hose secure on the actuators?

 

Yes vent hose was good, well the actuator it has on now is a cheap actuator i got online. The original one was caked and the contact points were completely gone. (Vacuum line was broken at the end so water and gunk got in it. I tried cleaning and soldering but the solder wouldn't stick. I only bought the cheap one so i wouldn't pay 1k+ on one and not be that. I basically built a Frankenstein using the switch sensors, and the gear from the oem. It goes in and out of 4hi/2hi like i mentioned above after cycling key. but the light wont stop blinking. I will pick up a multimeter today at home depot and give it another try tomorrow if i get a chance.

 

So i realized when truck is in 2wd the front driveshaft is hard to turn, does turn independently from rear, but the rear does move a bit if i twist it. Im thinking my problem is inside the transfer

 

You would need to jack a front wheel off the ground to see what's engaged.

 

I had it on a lift, front drive shaft would spin with the rear but i was able to stop it with my hand it was like the tc was in 4wd

 

In 2WD, you can spin the front driveshaft by hand freely with ALL 4 wheels on the ground.
It should spin pretty easy. That's what I do when I grease front driveshaft. Reach up and turn it.

Nothing else should turn. Not the front wheels and not the rear driveshaft.

 

Somes def up in my transfer case or my 2hi is not engaging all the way? Im able to spin it but it takes more muscle then usual (front tires dont spin) and if im in 4hi i cant spin it without spinning the rear one.

 

That's interesting, have you checked the transfer case fluid?
Did you get a proper multimeter?

 

Has anyone when they replaced the ADD with a new one opened it up and soldered the motor connection before installing? Seems like a way of getting a head of one of the failure points..

 

Can somone please post a readable version of the wiring diagram so I find the corresponding junctions / harnesses etc. My 4v4 fails after the transfer case locks the front drive shaft. The ECU does not give 12v to the front ADD motor.

 

What year is your truck?
I can grab it and post it when I get home.