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TIAGO/TIGOR AMT Gasoline
DTC Troubleshooting Guide
Version: 4.0
Date: 18-04-2017
Author: Sathi/Anupama
Page: 113 of 427
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
25 with all other ECU’s except TCU
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
DTC’s confirmation:-
After rectification, clear all DTC’s and ensure 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.