TIAGO AMT Gasoline DTC Troubleshooting Guide Version: 2.0 Date: 06-06-2016 Author: Sathi/Anupama Page: 113 of 424 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. 34. P0725-01: Engine Speed Input Circuit Signal wrong Overview: ISO Code P0725-01 Customer Symptom Transmission Fault Lamp ON Vehicle not picking up Gear shift request by lever disabled. No gearshifts Fault Effects (On Vehicle) Transmission Fault Lamp ON, Vehicle not picking up, Gear shift request by lever disabled, No gearshifts Lamp Status (If Any) Transmission Fault Lamp ON Fault Detection Condition This fault gets detected after Ignition On if the engine speed and clutch speed values differ by a calibratable amount. Normal Operating Condition Engine speed value is expected to be close to clutch speed if clutch is closed. Probable Trouble Area Wiring Harness Connections / EMS / TCU Healing Condition 2000 milliseconds after valid sensor signal Component Details: Engine Speed signal is transmitted via CAN bus to the TCU. Preliminary Checks: 1) Loose/ Damaged Crank sensor Connections. 2) Check for damage or back out of pins at EMS connector and TCU connector. 3) Check correct fitment of ground cable connections on vehicle chassis. Trouble Shooting:- Step Checks IF YES IF NO 1. Is there any rust/oxidation/pin backout observed on EMS or TCU connectors? Clean the Rust or repair or replace Go to Step 2 2. Check wiring harness electrical continuity between TCU pins 28 and 25 to EMS connector pins 144 and 132 respectively, Also check resistance between TCU pins 28 and 2 connected.(should be close to 60 ohm). Are both these checks OK? Go to Step 3 Establish continuity by rectifying harness connections as per the circuit schematic 3. Diagnose the crank sensor input to EMS (Refer EMS service manual), is there a problem with crank sensor or crank sensor to EMS connection? Ensure correct connection of crank input to EMS as per EMS service manual. Go to step 4 4 Is TCU power connections on TCU connector pins 5, 1, 3? Specifically check Ignition supply toggling with key on/off. Go to Step 5 Check and rectify harness power connections. 5 Connect the EMS diagnostic tool and check the value of engine speed with engine ON, is correct value observed? Replace the TCU Recheck EMS crank speed sensor connections - the following points by referring TCU parameters using TML diagnostic tool before handing over to customer. After key and engine ON with TML TCU diagnostic tool connected, monitor the engine speed and confirm that it represents the idle speed of the engine.
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