Vehicle Platform & ECU Name DTC Troubleshooting Data Ver: 1.0 Date: 30/11/2019 Author: ERC Page 390 of 610 Copyright by TATA MOTORS Ltd. This document must not be used in any way, such as copying and redistributing to third parties, without our consent P0426-86: Incorrect Immobilizer Key – EMS and VICM Authentication failed Overview: DTC Description as per ISO standard Incorrect Immobilizer Key ECU Pin Number - Customer Symptom Vehicle cannot be started. Fault Effects (On Vehicle) Vehicle cannot be started. Lamp Status Immobilizer status lamp will come ON Fault Detection Condition (Root cause) This fault occurs when AES-Key is not programmed correctly in either EMS or VICM ECU Normal Operating Condition Authentication between EMS & Immo is successful Probable Trouble Area AES key not programmed correctly either in EMS / Immo, Immo Unit, EMS ECU. Healing Condition After Successful Immo Pairing, In the same Ignition cycle if EMS / Immo hasn’t entered anti scanning mode. After Successful Immo pairing, give a power latch of 20 secs and turn the Ignition ON. NOTE (applicable only for Altroz): In case of “Incorrect Immobilizer Key – EMS and VICM Authentication failed” and “No response received by EMS from VICM ECU(P” only one fault gets logged,which is “Incorrect Immobilizer Key – EMS and VICM Authentication failed (P0426-86)” Component Details: Immobilizer system is designed to prevent vehicle theft by electronically disabling the engine starting system. The engine can be started only with vehicle’s original immobilizer ignition key, which has an electronic identification programmed code. Immobilizer unit (ICU) is an add-on part on the ignition switch, fitted on the steering column. The engine can be started only with the vehicle’s original immobilizer ignition key. The electronic key communicates the identification code to ICU when the key is turned to the "Ignition ON" position. Engine will allow the Vehicle cranking only if the authentication between EMS and IMMO is successful and Transponder / key used for cranking is paired to the Immobilizer unit. Preliminary Checks Check whether the customer voice / view about the issue is matching with the fault effects mentioned above. If yes, go ahead with next steps. If not, check for other DTC’s presence. Check whether similar complaints are earlier reported. If yes, perform the preliminary checks with respect to earlier issue closure.
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