2021 Transfer case shift motor.

[mtnmikev]

So I tested my shift motor by applying 12v to the motor and it indeed turned. But now when I reinstalled it's still stuck in 4low but the 2wd light is on.
Originally it shifted into 4low after parking for a bit after driving thru water. When I started it was in 4low with a "check 4wd" error on the dash and will not shift out or would the light change on the selector.
Connected a scanner and it says there are no codes.
Any and all advice and questions welcome.

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[airline tech]

A few things to check.
Fuses at the Engine Bay Fuse Box:
Fuse 66 (25A) Transfer Case (Bottom Side of Fuse Box) will have to physically gain access to the bottom of the fuse box, it's kind of a PITA.

Fuse 23 (7.5A) DC/DC Convertor

Fuse 66 is going to be the most likely to blow.

There are 3 relays, 1 relay is integrated into the Fuse Box (4WD Relay) (Engine Bay Box)
Relay (R42) 4WD CW Relay (on-Top)
Relay (R86) 4WD CCW Relay (On-Top)
You can possibly swap these 2 relays, they can be a pain to pull out, just take it slow and easy they are a tight fit. Don't rock them too much.
However, it does take both relays working in unison to power the shift motor.
But may show a failed relay if you gain (one direction of movement) to shift it out of 4-Lo

Sorry, I do not know off hand, which direction is required to move the shift lever from 4 Low to 4-Hi and 2 Hi

You may try to perform a PCM Self-Test, even though it has not coded yet, this may reset the system.

If you had the shift motor off, did you only apply power to the larger pins?
The larger pins are the 12-volt circuit.
the smaller 3 pins are the 5-Volt reference circuit.
This circuit provides the control ground for the 2 relays (CW and CCW) to drive the shift motor.

With the motor removed you should be able to manually shift the transfer case out of 4 Low and into 2 HI, I do not know if that shaft is external or internal, either way if it is physically in 4-Low it is going to be at a internal stop, rotate it 2ea physically de-tented clicks the opposite way, to place it physically into 2 HI, then you will have to manually position the motor shaft to match the alignment slot on the case
This will at least make it drivable (if you have lost electric control)

You are possibly indicating 2 Hi on the dial due to the fact you had the connector disconnected and without power at the shift motor it cannot provide a feedback of actual current position to the PCM , so it defaulted to 2 HI

 

[mtnmikev]

Thank you! This is the kind of response I was hoping for.

I only applied 12v to the larger pins.

I have also checked each pin for short to ground and they all meter good.

Apon my last removal of the motor it was burning hot (not normal?)
with that fact I find it odd that it meters out good........

I also metered the power (12v) pins from the vehicle while running and got jumpy readings from 14v to 0, settling on 0v. This to me could indicate the dc to dc converter (fuse23)

I'll check the fuses and manually shift and will check back in.

Thanks again.

 

[JasonTremor]

Be sure to put wheel chocks in front and behind your wheels if you are going to manually shift the transfer case back to 2wd. Wouldn't want it to roll over anyone.

 

[airline tech]

Thank you! This is the kind of response I was hoping for.

I only applied 12v to the larger pins.

I have also checked each pin for short to ground and they all meter good.

Apon my last removal of the motor it was burning hot (not normal?)
with that fact I find it odd that it meters out good........

I also metered the power (12v) pins from the vehicle while running and got jumpy readings from 14v to 0, settling on 0v. This to me could indicate the dc to dc converter (fuse23)

I'll check the fuses and manually shift and will check back in.

Thanks again.

The jumping voltage is normal, it’s not a constant power, only powers during shift action.
It’s the shift motor looking for a feedback in the VREF circuit to turn off voltage, you may try manually moving the shift motor to get it to stop.

Think of this motor as the Blend Door Actuator, clicking and popping, except not making noise it is overheating instead.

So my guess it is a bad shift motor or a stuck relay that won’t release the power, the PCM is pulsing the power on and off 14 - 0.

 

[airline tech]

Another possible is that the switch is seeing a selection to 2-Hi, and is sending the request to the actuator but it cannot physically move the transfer case shifter.
You may try having it removed then let it power on its own disconnected to see if it will move.
You should be able to physically move the shift rod on the transfer case without much resistance. If it takes a lot of force then the transfer case is locked up - frozen

 

[mtnmikev]

Pulled all the fuses and they are all good. Tested and cycled the relays and they are good. There is signs of water in the top of the fuse box leading right to one of the relays. I blew everything out with air and let dry.
All seems to be working as normal now!!!!
Thanks for the tips Airline tech.

 

[airline tech]

Pulled all the fuses and they are all good. Tested and cycled the relays and they are good. There is signs of water in the top of the fuse box leading right to one of the relays. I blew everything out with air and let dry.
All seems to be working as normal now!!!!
Thanks for the tips Airline tech.

Cool , good find

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