TIAGO

TIAGO AMT Gasoline

DTC Troubleshooting Guide

Version: 2.0

Date: 06-06-2016

Author: Sathi/Anupama

Page: 257 of 424

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.

81.

P2905-03: Gearbox System unintended disengage

Overview:

ISO Code

P2905-03

Customer Symptom

No gearshifts,

Vehicle not picking up ,

shift to neutral while driving in reverse gear

skipping of gears

Fault Effects (On Vehicle)

No gearshifts,

Vehicle not picking up ,

shift to neutral while driving in reverse gear

skipping of gears

Lamp Status (If Any)

Transmission Fault Lamp OFF

Fault Detection Condition

This fault gets detected after Ignition On during a gearshift

when TCU detects that a gear is unintentionally disengaged

without a command.

Normal Operating Condition

TCU monitors that the time for disengagement/engagement of

a gear is within an allowable time

Probable Trouble Area

Gear Electro valve / TCU / Gearbox

Healing Condition

Fault is cleared on next ignition Power ON

Component Details:

In an AMT system, the gear shifting is actuated through 3 electrovalves viz. 2 gear electrovalves for shifting between odd and

even gears and 1 shift electrovalves for shifting between ranks.

Preliminary Checks:

1) Loose/ Damaged Valve body and TCU mountings.

2) Check for damage or back out of pins at TCU connector.

3) Check visibly for kit Oil leakage and ensure with diagnostic tool that kit oil pressure is in range 38 - 51 bar

4) Check for mechanical damage to the Valve body (MGA), kit and gearbox mechanical fitments

5) Check correct fitment of ground cable connections on vehicle chassis.

Trouble Shooting:-

At first occurrence of this DTC, clear the DTC and drive the vehicle through all gears for ~5 kms, on repeat occurrence of this

DTC check the following.

Step Checks

IF YES

IF NO

Through the TML diagnostic tool, Read the

Parameters

Compare the values to the nominal values

and tolerances below:

:xx mm

:yy mm

Are the read values correct within

tolerance limits?

Go to Step 2

Perform a Grid learning

procedure through the

TML diagnostic tool, Rerun

the vehicle through the

drive test.

Check the kit & gearbox assembly for

mechanical damage, stuck gear actuator,

synchro ring damage, fork damage, gear

damage, lubrication etc?

Go to Step 3

Rectify/replace the

gearbox

3. Check gear electrovalves electrical

connections by following same procedure

Go to Step 4

Establish continuity by

rectifying harness