Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Normal Operation and Fault Conditions
With the ignition ON, the ABS module sends messages to the SASM over the HS-CAN 2. If the SASM does not receive these messages within a certain time frame (usually less than 1 second), the SASM sets DTCs. For information on the messages sent to the SASM by the ABS module, refer to the Network Message Chart in Description and Operation of the Anti-Lock Brake System (ABS) and Stability Control article.
| DTC | Description | Fault Trigger Conditions |
|---|---|---|
| U0121:00 | Lost Communication With Anti-Lock Brake System (ABS) Control Module: No Sub Type Information | Sets in continuous memory and on-demand when the SASM detects any of the ABS module messages are missing. This can be due to a ABS module failure, a circuit failure on the HS-CAN or an excessive load on the network. |
NO RELATED
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.