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TIAGO/TIGOR AMT Gasoline
DTC Troubleshooting Guide
Version: 4.0
Date: 18-04-2017
Author: Sathi/Anupama
Page: 221 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.
70.
P1884-04: Reverse Lamp relay –open circuit
Overview:
ISO Code
P1884-04
Customer Symptom
Reverse lamp not switching ON
Fault Effects (On Vehicle)
Reverse lamp not switching 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 an open circuit is detected.
Normal Operating Condition
TCU does not detect open circuit
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
1.
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
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
3.
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
4
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
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.
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.