HARRIER BOOK 2

TATA MOTORS Ltd.

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SRS / Airbag

ECU – DTC Troubleshooting Guide

Version: 14.0

Date: 14-February-2017

Prepared by:Airbag COC Review &

Approved by:Sanjeev VM

Page: 367 of 549

U0100-08:- Lost Communication With ECM/PCM "A"- Bus Signal / Message Failures

Overview:

ISO Code

U0100-08

Customer Symptom

SRS Warning Lamp continuously ON in Instrument Cluster.

Fault Effects (On Vehicle)

Co-driver SBR chime functionality will be affected

Lamp Status (If Any)

SRS Warning Lamp continuously ON in Instrument Cluster.

Fault Detection Condition

RCM (SRS/Airbag) ECU is not receiving vehicle speed data from

ECM/PCM.

Normal Operating Condition

ECM ECU should communicate properly with RCM (SRS) ECU.

Probable Trouble Area

CAN_H and CAN_L wires (Wiring

harness), ECU connectors, ECU pins.

Healing Condition

RCM (SRS) ECU should receive vehicle speed data from ECM

ECU at the required intervals (20/100 msec).

Airbag Warning Lamp behavior for U0100-08 DTC:-

U0100-08

IVN DTC is healed in the same IGN cycle; once corresponding failure detection conditions are not present.

However, Airbag Warning Lamp (triggered due to this failure/DTC) will turn off in following two conditions.

c. When above mentioned DTC is in healed state and Clear DTC command is sent; in this case Lamp will be

OFF in same IGN cycle

d. When above mentioned DTC is in healed state and IGN OFF/ON (1 time) operation is done.

This is implemented as per supplier’s strategy.

Component Details:-

Airbag ECU:- It is fitted in the floor of central console in the car. The Airbag Electronic Control Unit (ECU) controls the

deployment system to allow an appropriate igniting of the Airbags and belt pre-tensioners to restrain the driver and

passengers.

Preliminary Checks:-

1. Ensure the proper locking of Airbag ECU wiring harness connectors in the vehicle by the locking sound.

2. Check resistance between diagnostic CAN pin number 6 and 14 in OBD connector. It should be 120 ohm.

3. Check for short conditions between CAN_H-CAN_L, CAN_H-GND, CAN_L-GND, CAN_H-Vbat and

CAN_LVbat. There should not be any short circuit conditions.

4. Check continuity between ECM CAN_H (pin no. 19) vehicle side connector to OBD connector CAN_H (pin no.

6) and CAN_L (pin no. 18) vehicle side connector to OBD connector CAN_L (pin no.14).

5. Read IVN DTCs in IPC in Ignition ON condition.

Trouble Shooting:-