TIAGO

TIAGO AMT Gasoline

DTC Troubleshooting Guide

Version: 2.0

Date: 06-06-2016

Author: Sathi/Anupama

Page: 224 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.

71.

P1884-02: Reverse Lamp relay short to supply

Overview:

ISO Code

P1884-02

Customer Symptom

Reverse lamp always ON

Fault Effects (On Vehicle)

Reverse lamp always ON

Lamp Status (If Any)

Transmission Fault Lamp OFF

Fault Detection Condition

This fault gets detected after Ignition On when reverse lamp

output is commanded OFF and a short to supply is detected.

Normal Operating Condition

TCU does not detect short to supply.

Probable Trouble Area

Wiring Harness Connections / Reverse lamp relay / TCU

Healing Condition

2000 milliseconds after valid detection of healed condition

Component Details:

Reverse lamp output is a digital output from TCU to EMS which is driven high to turn ON the reverse lamp through a reverse

lamp relay.

Preliminary Checks:

1) Check for damage/loose fit or back out of pins at TCU 28 pin vehicle connector, Reverse lamp relay and relay box.

2) Check for visible damage to TCU pins.

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

Trouble Shooting:-

Step Checks

IF YES

IF NO

Is there any rust/oxidation/damage

observed on TCU 28 pin vehicle connector

Terminals?

Clean the Rust or repair or

replace

Go to Step 2

Is there wiring harness electrical continuity

between TCU pin 2 to Reverse lamp relay

input pin? Also check for any short to

battery or ground on pin 2.

Go to Step 3

Establish continuity by

rectifying harness

connections as per the

circuit schematic

Is ground connection proper on reverse

lamp relay input side?

Go to Step 4

Establish continuity by

rectifying harness

connections as per the

circuit schematic

Check the TCU ignition and power

connections on Pins 5, 1 and 3 respectively.

Check for ignition pin toggling to 12 V with

ignition key On-Off. Connections are OK?

Go to Step 5

Establish continuity by

rectifying harness

connections as per the

circuit schematic

5 Replace the Reverse lamp relay, problem

persists?

Replace the TCU

the following points by referring TCU parameters using TML diagnostic tool

before handing over to customer.

Check for proper Reverse lamp functioning.

Drive the vehicle through all gears in both Automatic and Manual modes

Ensure no DTC is active and Transmission Fault Lamp is OFF.

Circuit Schematic Diagram: