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OSPREY- Application
DTC Troubleshooting Data
Version: 4.0
Date: 10-02-2017
Prepared by: Mithipati Prasad
Checked by: G S Raju / Senthilnathan S
Page: 437 of 654
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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.
P1572: Brake Light Switch Fault
Overview:
Description as per ISO standard
Brake Light Switch Fault.
Customer Symptom
Brake Lamp / Stop Lamp will either be turned ON continuously or
turned Off continuously (irrespective of Brake pedal press).
ECU PIN No
39
Fault Effects (On Vehicle)
Brake Lamp / Stop Lamp will either be turned ON continuously or
turned Off continuously (irrespective of Brake pedal press).
Lamp Status (If Any)
-
Fault Detection Condition
This fault gets logged if EMS detects transitions in Brake safety
switch / Brake redundant switch input but not in Brake light switch
/ Brake main switch input.
Normal Operating Condition
EMS ECU finds coherence between Brake Switch inputs.
Probable Trouble Area
Wiring harness Connections between Brake light / Main Switch
and EMS ECU, Improper Brake Switch Setting, Brake safety
switch, EMS ECU
Component Details:
For safety reasons, Brake pedal is equipped with two Switches. These switches transition their states when the brake
pedal is pressed. EMS ecu uses the brake press information in its control strategies like Torque demand calculation, Gear
Shift indication, Accelerator pedal stuck detection, vehicle start function when clutch sensor fails etc.,
Preliminary Checks:
x
Check whether the customer voice / view about the issue is matching with the fault effects mentioned above. If yes,
go ahead with next steps. If not, check for other DTC’s presence.
x
Check whether similar complaints are earlier reported. If yes, perform the preliminary checks with respect to earlier
issue closure.
x
Check whether the Brake Light Switch / Brake safety Switch are either stuck open or closed.
x
Check, if the Brake lights are on even when no brake pedal is pressed.
x
Loose/ Damaged Connections between Brake Switch connector and EMS ECU.
x
Check for back out / damage of pins at ECU connector.
x
Check for back out / damage of pins at Brake switch connector.
x
Check for any physical damage of EMS ecu / Brake switches connectors.