Transfer case troubleshooting

Question moved from Computer category to model category.

IDO or IOD?
combus or Can Bus?

https://www.google.com/search?q=2012+Nissan+Titan+IDO+fuse

U0101 - OBD II Trouble Code: Lost Communication with TCM

RepairPal.com https://repairpal.com > obd-ii-code-u0101-lost-commu...
Code U0101 stands for Lost Communication with TCM. The transmission control module (TCM) is the computer that controls your vehicle's transmission.

U0101 Code: Lost Communication with TCM

CarParts.com https://www.carparts.com > ... > OBD-II Trouble Codes
Sep 28, 2023 - DTC U0101 stands for "Lost Communication with TCM." DTC U010 is set when the transmission control module is unable to receive or send ...

the p1682 for pontiac is an ignition problem https://www.700r4transmissionhq.com/pontiac-g6/ as to the u0101 that can be related this code can pop up with a low voltage problem to tcm failure https://repairpal.com/obd-ii-code-u0101-lost-communication-with-tcm

First I would check the PowerTrain Control Module for any thrown diagnostic troubleshoot codes by using a code reader.
I am unsure if there is a separate transmission computer module for your vehicle. If there is, a code reader will be necessary.
I will assume that the "check engine light" or MIL did not illuminate or the 4wd or 2wd light flash since you did not mention it.
If the car can move forward and backward in 4wd, then it's not the transmission itself since power is transferred through the output shaft of the transmission to the transfer case.
I would think that 4-wheel drive mode is not fully disengaging-
Check the vacuum hoses for damage, crimps, or leaks
Check and test the vacuum actuator
check and test the transfer case switch
check the vacuum actuator cable for damage or defect
check and test the encoder motor actuator on the transfer case
Buy a repair book or shop manual specific to the year, make, and model of the car you are having problems with that offers descriptive troubleshoot and repair procedures with illustrations. You can purchase them as soft or hardcover books or electronic downloads. Here are a few publishers, Chilton, Haynes, Motors, etc. Do an online search or go to your local auto parts store.
Otherwise, if you are not savvy in automotive diagnostic & repair, I would highly recommend flat-bedding the vehicle to a reputable transmission repair shop that has ASE certified transmission technicians. The reason you need to place your vehicle on a flat-bed car carrier - is to avoid serious damage to the transmission.

To Troubleshoot Transfercase stuck in 4wd issue.Click the link below and follow the details:
http://www.allcarhelp.com/2015/04/transfer-case-stuck-in-4-wheel-drive.html

This will help.
Thanks.

Hi Patricia:
DTC U0101 - TCM Message Unavailable
I suggest to check description and solution details HERE.

Hope this helps; also keep in mind that your feedback is important and I`ll appreciate your time and consideration if you leave some testimonial comment about this answer.

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These are transmission control module can communications codes. ealer will need to repair these for sure.

0073 ambient air temperature sensor circuit high input 0101 mass or volume air flow circuit range performance problem it sounds like the mass air flow sensor is dirty check with your G.M. dealer to see if its still in warranty

co327 is a code for your transfer case encoder motor and the U codes are communication codes. Most likely cause is the encoder motor needs replacement

IPC - instrument cluster - BCM - body control module (computer )

U0101 - your vehicle has a serial data communication network that all the modules communicate on , this U0101 means one isn't talking . You best bet take to a qualified repair shop .