NEXON DIAGNOSTIC MANUAL

Nexon Gasoline – EMS ECU Bosch

DTC Troubleshooting Manual

Version: 0.1

Date: 26-08-2017

Prepared By: Sunu S Babu/Yogesh Jadhav

Checked By: Yeshwant Jadhav

Approved By: Satish Kumar

Document Part No: 2921 02 224 A1736

Page: 818 of 1203

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.

P0646-11: A/C Clutch Relay Control Circuit Low – Circuit Short to Ground

Overview:

ISO Code

P0646-11

Customer Symptom

1. A/C Clutch may get ON always.

2. May damage the A/C Clutch.

Fault Effects (On

Vehicle)

1. AC fan /AC compressor will not work.

2.AC

load more /less than expected

Lamp Status (If Any)

CE lamp ON after 1 drive cycle

Fault Detection Condition This fault gets logged if the AC Clutch relay control pin of EMS ECU is Short

circuited to GND

Normal Operating

Condition

Healthy wiring harness connections between AC Clutch Relay and EMS ECU

Probable Trouble Area

AC Wiring harness Connections

Healing Condition

Ignition On and after 1 drive cycle of fault rectification

Fault Permanent Deletion

1. Clear DTC Command form Scan tool

2. Stack Over Flow.

3. 40 warm up cycles.

4. ECU Flashing.

5. ECU Power-Fail

Component Details:

AC Compressor has a magnetic Clutch; Coil of the magnetic clutch is energized by EMS ECU. After getting

Energized, Clutch engages the compressor to the EMS ECU.

Preliminary Checks:

1) Loose/ Damaged Connections between AC Compressor Relay and EMS ECU.

2) Loose/ Damaged Connections between AC Compressor Relay and Battery supply or Ground.

3) Check for back out of pins at ECU connector.

4) Check for damage of pins at ECU connector.

5) Check the continuity from Relay to the ECU pin and from battery/Ground to Relay.