Codes U0100 and 0101, will not start?

MALLYBOY

MEMBER
2018 TOYOTA HIGHLANDER
3.5L
V6
4WD
AUTOMATIC
134,315 MILES

This vehicle cannot start when cranked, I diagnose and pick the above codes. U0100- loss communication with ECM/PCM a, u0101-loss communication with TCM. So, I need ECM pinout diagram, ECM communication diagram from dlc to ECM, component location diagram, fuse box diagram and power diagram to trace this fault.

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Tuesday, November 5th, 2024 AT 5:59 AM

5 Replies

KEN L

MASTER CERTIFIED MECHANIC
54,137 POSTS

Was this car under water? I would start by checking all fuses, make sure the battery is good before you begin. Also, check for any main grounds that have been left off. They don't have pin outs but I did get the engine and transmission wiring diagrams so you can check for power and grounds.

U0100 - Lost Communication with ECM/PCM:
U0101 - Lost Communication with Transmission Control Module (TCM):

Here are the fuse locations, please check the fuses for power as well with the ignition system on.

https://www.2carpros.com/articles/how-to-check-a-car-fuse

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Tuesday, November 5th, 2024 AT 1:10 PM

MALLYBOY

MEMBER
334 POSTS

The vehicle was not under water. You did not include computer data I.E communication line circuit and communication junction connector's location to check why the ECM is not communicating, please send the computer data line circuit and data line junction connectors and their locations. Thanks

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Tuesday, November 5th, 2024 AT 7:50 PM

MALLYBOY