TATA BSVI Gasoline_Bifuel Program – EMS ECU Bosch DTC Troubleshooting Service Manual Version: 1.9 Date: 24-01-2022 Prepared By: Veer K. Singh / Prudhvi B Varma Checked By: Yeshwant Jadhav Approved By: Sanjeev M. Document Part No: 2921 02 xxx xxxx Page: 1076 of 1692 Copyright © TATA MOTORS Ltd. This document must not be used in any way, such as copying and redistributing to third parties, without the consent of author. U0402-81: CAN bus TCU invalid failure-Invalid serial data received Overview: ISO Code U0402-81 Customer Symptom Engine come to forced neutral condition Fault Effects (On Vehicle) Vehicle will not move (remain standstill) as it comes to forced neutral condition from transmission ECU Lamp Status (If Any) Lamp OFF Fault Detection Condition Invalid Data Received from TCM-invalid serial data received Normal Operating Condition ECM ECU and TCU ECU communicate properly with each other Probable Trouble Area CAN messages are not received correctly form TCU Healing Condition After 1 engine cycles Fault permanent deletion 1. Scan tool Service 14. 2. Stack Over Flow. 3. 40 warm up cycles. 4. ECU Flashing. 5. ECU power fail Preliminary Checks: 1. Check ECM is communicating with TML diagnostic DTC or not. 2. If not, check for short conditions between CAN HIGH-CAN LOW, CAN HIGH-GND, CAN LOW-GND, CAN HIGH-Vbatt and CAN LOW-GND at ECM vehicle side wiring harness (pin details are provided with schematic in the document). There should not be any short Circuit conditions. 3. There should be continuity between vehicle side wiring harness with following pins. i. IPC CAN HIGH (pin. 6) to ECM CAN HIGH (C1, 132) and IPC CAN LOW (pin. 5) to ECM CAN LOW (C1, 144) Continuity should be there. 4. Read IVN DTCs in ECM after IGN ON condition with TML diagnostic tool. 5. Check If any one or all of the following signals are logged: i. clutch engaged status signal from TCU is implausible ii. current gear status signal from TCU is implausible iii. when the status of the current engaged gear is not available
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