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 PCM sends messages to the ABS module through the GWM over the HS-CAN. The TCM is an internal component of the PCM. If the ABS module does not receive these messages within a certain time frame (usually less than 1 second), the ABS module sets DTCs. For information on the messages sent to the ABS module by the PCM, 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 |
|---|---|---|
| U0100:00 | Lost Communication With ECM/PCM "A": No Sub Type Information | This DTC when the ABS module does not receive any messages from the PCM. This can be due to a PCM failure, a circuit failure on the HS-CAN or an excessive load on the network. |
| U0101:00 | Lost Communication With TCM: No Sub Type Information | This DTC when the ABS module does not receive any of the transmission message from the PCM. This can be due to a PCM failure, a circuit failure on the HS-CAN or an excessive load on the network. |
| U0401:00 | Invalid Data Received from ECM/PCM "A": No Sub Type Information | This DTC sets if the ABS module receives invalid data in any one of several messages from the PCM. This can be due to a PCM failure, a circuit failure on the HS-CAN or an excessive load on the network. |
| U0401:86 | Invalid Data Received from ECM/PCM "A": Signal Invalid | This DTC when the ABS module does not receive the accelerator pedal message from the PCM for longer than 5 seconds. This can be due to a PCM failure, a circuit failure on the HS-CAN or an excessive load on the network. |
| U0402:00 | Invalid Data Received from TCM: No Sub Type Information | This DTC sets if the ABS module receives invalid data in any one of the several transmission messages from the PCM. This can be due to a PCM failure, a circuit failure on the HS-CAN or an excessive load on the network. |
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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.
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