13

14

Engine Control Module

Pre-catalytic Oxygen Sensor

Post-catalytic Oxygen Sensor

Vehicle 
Speed 
Sensor

FE02-2103b

Engine

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2.2.7 Diagnostic Information and Procedures
2.2.7.1 Diagnostic Description

Before diagnose the control system, please refer to 

2.2.2.1

 

Overview

and

2.2.3.1

 

System Working Principle

. Understand and become

familiar with control system working principle and then start systematic diagnosis, so that in the event of faults it will help determine
the correct Diagnostic Steps, more importantly, it will also help to determine whether the customer described situation is normal or
not.

Any control system fault diagnosis should start with "Control System Check" as a starting point. "Control System Check" will guide
the service personnel to take the next logical step to diagnose the fault. Understand and the correct use of diagnostic flow charts
can reduce diagnostic time and avoid misjudging a component.

2.2.7.2 Control System Check

Before the control system check, please do following preliminary checks:

1. Check the battery terminal voltage to ensure an adequate power supply and a stable voltage.

2. Check the battery cables, clean and tighten.

3. Check the easy to access system components whether there are obvious damages that may cause the symptoms, such as

vacuum tube damage and the reliability of wiring harness connectors connection.

4. Check control module and battery ground points whether there are copper oxidizing or signs of loosening.

5. Check control system whether it is likely to affect the normal system operation after the installation of aftermarket equipments.

Diagnostic Steps:

Step 1

Verify customer described faults.

Next

Step 2

Connect a scan tool.

(a)

Install the scan tool.

(b)

Turn on the scan tool.

Is the scan tool connected?

No

Go to step 11

Yes

Step 3

Start communication between the scan tool and the engine control module.

(a)

Turn the ignition switch to "ON", but do not Start the engine.

(b)

Try to establish communication between the scan tool and
engine control module (ECM) .

Can the scan tool communicate with engine control module?

No

Go to step 14

Yes

Step 4

Start the engine and run at idle speed. Can the engine start?

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Control System JL4G18-D

Engine

No

Refer to 

2.11.7.4

 

Engine Can Not Start

Yes

Step 5

Select engine control module DTC code reading function. Is there any system DTC code?

No

Refer to 

2.2.7.3

 

Intermittent Fault Check

Yes

Step 6

Record and clear the DTC code.

Next

Step 7

Verify fault symptoms.

Results

To Step

Fault does not appear.

Yes

Fault appears.

No

No

Go to step 9

Yes

Step 8

Simulate fault symptoms.

Next

Step 9

Check control system whether there is a DTC code.

Results

To Step

DTC Code

Yes

No DTC Code

No

No

Refer to 

2.5.7.6

 

Fault Symptom Table

Yes

Step 10

Repair according to the DTC code. Refer to 

2.2.7.11

 

DTC Code Index

.

Step 11

Connect the scan tool to a proper operated vehicle. Can the scan tool be turned on?

No

The scan tool failed. Replace the scan tool.

Yes

Step 12

Check datalink connector power supply circuit.

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Control System JL4G18-D

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FE02-5000b

1

2

3

4

5

6

7

8

10

11

12

13

14

15

16

9

Datalink Connector IP12

(a)

Turn the ignition switch to "ON" position.

(b)

Measure the voltage between datalink connector IP12
terminal 16 and a reliable ground.

Standard Voltage: 11-14 V

Is the voltage normal?

No

Check if the circuit between terminal 16 and
the IF21 fuse open.

Yes

Step 13

Check datalink connector ground circuit.

FE02-5001b

1

2

3

4

5

6

7

8

10

11

12

13

14

15

16

9

Datalink Connector IP12

(a)

Turn the ignition switch to "OFF" position.

(b)

Measure the voltage between datalink connector IP12
terminal 4 and a reliable ground.

Standard Resistance: Less than 1 Ω

No

Check if the circuit between terminal 4 and the
ground open.

Yes

Step 14

Is the engine running properly?

No

Engine immobilizer control module and ECM
communication failure, check and repair the
relevant components. Refer to

2.5.7.12

 

Engine Anti-theft Warning Lamp

Flashing, Vehicle Can Not Start

Yes

Step 15

Terminal continuity check.

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