NEXON NEW MCE-2 DCT BS VI DTC Troubleshooting Guide Version: 1.0 Date: 16-06-2023 Author: Akash/Rahul Page:256 of 645 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. 74. P1657-12 High side stuck: Short Circuit to Battery Overview: ISO Code P1657-12 Customer Symptom • Transmission fault lamp ON • Mileage based reaction after 100 km • Engine torque will be limited, via Limphome Fault Effects (On Vehicle) • Transmission fault lamp ON • Mileage based reaction after 100 km • Engine torque will be limited, via Limphome Lamp Status (If Any) Transmission fault lamp ON Service indication 0x2 Fault Detection Condition High side connected to Battery for >70ms Normal Operating Condition TCU does not detect any fault Probable Trouble Area 1. External wiring loom of the transmission for any damage. 2. TCU. 3. Internal wiring loom & hydraulic block of the transmission. Healing Condition The reaction is cleared at SW restart and during driving if the detection is FALSE for more than 100 ms Component Details: Clutch actuator 1 & 2 mounted in hydraulic control unit and makes internal electrical contact with the TCU. Preliminary Checks: 1) Battery voltage 2) Check for damage or back out of pins at TCU connectors. 3) Check correct fitment of ground cable connections on vehicle chassis (tightness, corrosion of mounting bolts etc.) Trouble Shooting:- Step Checks IF YES IF NO 1. Check the external wiring loom of the transmission for any damage. If wiring loom is damaged, replace the wiring loom. Clear the DTC and check if the DTC does not come back. Go to step 2 2. If problem persists, test with replacement TCU Clear the DTC and check if the DTC does not come back. Go to step 3 3. If problem persists with the replacement TCU then check internal wiring loom & hydraulic block of the transmission. If damage is visible, replace the hydraulic block & transmission oil. Go to step 4 4 After replacing the hydraulic block & transmission oil, perform the necessary adaptions. Clear the DTC and check if the DTC does not come back. • Resistance Check Solenoids , Pressure sensors mounted on HCU should be checked for resistance if there is DTC triggered. Below table reflects the signals for each solenoid and pressure sensor and range of acceptable resistance.
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