# DTC U0121 x 4. "4 modules not communicating to EBCM"

**URL:** <https://community.cartalk.com/t/dtc-u0121-x-4-4-modules-not-communicating-to-ebcm/190389>\
**Category:** Maintenance/Repairs\
**Tags:** terrain, abs, gmc\
**Created:** [May 2, 2023, 3:54pm UTC](https://community.cartalk.com/t/dtc-u0121-x-4-4-modules-not-communicating-to-ebcm/190389 "2023-05-02T15:54:49Z")\
**Posts on this page:** 3\
**Page:** 3

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**Author:** ![angrysmileyface\_191815](https://avatars.discourse-cdn.com/v4/letter/a/d2c977/32.png) [@angrysmileyface\_191815](https://community.cartalk.com/u/angrysmileyface_191815)\
**Post date:** [November 6, 2024, 1:03pm UTC](https://community.cartalk.com/t/dtc-u0121-x-4-4-modules-not-communicating-to-ebcm/190389/41 "2024-11-06T13:03:15Z")

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Did you ever find resolution to your issue? I hit a raised speed bump in a parking lot and now have a bunch of Non-Comm codes to the ABS module and ABS/SKID lights with a Service Power Steering message/chime upon car start. Also have the dead battery symptom since the car sits.

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**Author:** ![DJ44](https://avatars.discourse-cdn.com/v4/letter/d/aeb1de/32.png) [@DJ44](https://community.cartalk.com/u/DJ44)\
**Post date:** [November 8, 2024, 8:56pm UTC](https://community.cartalk.com/t/dtc-u0121-x-4-4-modules-not-communicating-to-ebcm/190389/42 "2024-11-08T20:56:57Z")

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I have been driving around with this problem for 3 years - ever since the dealer didn’t mention anything about the TWO TSBs that might explain this problem from just a wiring harness and/or connector corrosion problem. They went straight to the $2000 module and didn’t sound very confident that would solve it. So I don’t know what to do and have been hoping that someone else somewhere online would post a solution. I can’t afford to throw away $2k and just hope there a chance it works.

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**Author:** ![angrysmileyface\_191815](https://avatars.discourse-cdn.com/v4/letter/a/d2c977/32.png) [@angrysmileyface\_191815](https://community.cartalk.com/u/angrysmileyface_191815)\
**Post date:** [November 12, 2024, 2:58pm UTC](https://community.cartalk.com/t/dtc-u0121-x-4-4-modules-not-communicating-to-ebcm/190389/43 "2024-11-12T14:58:15Z")

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I will check on the TSBs This car spent most of its life in FL, TN, and TX, and has slightly more body issues than it does corrosion.

[Previous page](https://community.cartalk.com/t/dtc-u0121-x-4-4-modules-not-communicating-to-ebcm/190389.md?page=2)