Nissan Pathfinder (2012 year). Manual - part 313

ENGINE CONTROL SYSTEM

EC-585

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EC-586

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ENGINE CONTROL SYSTEM

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DIAGNOSIS AND REPAIR WORK FLOW

EC-587

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BASIC INSPECTION

DIAGNOSIS AND REPAIR WORK FLOW

Trouble Diagnosis Introduction

INFOID:0000000007799379

INTRODUCTION

The engine has an ECM to control major systems such as fuel con-

trol, ignition control, idle air control system, etc. The ECM accepts

input signals from sensors and instantly drives actuators. It is essen-

tial that both input and output signals are proper and stable. At the

same time, it is important that there are no malfunctions such as vac-

uum leaks, fouled spark plugs, or other malfunctions with the engine.

It is much more difficult to diagnose an incident that occurs intermit-

tently rather than continuously. Most intermittent incidents are

caused by poor electric connections or improper wiring. In this case,

careful checking of suspected circuits may help prevent the replace-

ment of good parts.

A visual check only may not find the cause of the incidents. A road

test with CONSULT (or GST) or a circuit tester connected should be

performed. Follow the Work Flow on “WORK FLOW”.

Before undertaking actual checks, take a few minutes to talk with a

customer who approaches with a driveability complaint. The cus-

tomer can supply good information about such incidents, especially

intermittent ones. Find out what symptoms are present and under

what conditions they occur. A Diagnostic Worksheet like the example

on “Worksheet Sample” should be used.

Start your diagnosis by looking for conventional malfunctions first.

This will help troubleshoot driveability malfunctions on an electroni-

cally controlled engine vehicle.

WORK FLOW

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EC-588

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DIAGNOSIS AND REPAIR WORK FLOW

Overall Sequence

Detailed Flow

1.

GET INFORMATION FOR SYMPTOM

1. Get the detailed information from the customer about the symptom (the condition and the environment

when the incident/malfunction occurred) using the “Diagnostic Work Sheet”.

2. Ask if the customer requests I/M examination.

Malfunction information, obtained>>GO TO 2.

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EC-589

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No malfunction information, but a request for I/M examination>>GO TO 13.

2.

CHECK DTC

1. Check DTC.

2. Perform the following procedure if DTC is displayed.

-

Record DTC and freeze frame data. (Print them out with CONSULT or GST.)

-

Erase DTC.

-

Study the relationship between the cause detected by DTC and the symptom described by the customer.

(Symptom Matrix Chart is useful. Refer to 

EC-947, "Symptom Matrix Chart"

.)

3. Check related service bulletins for information.
Are any symptoms described and any DTCs detected?

Symptom is described, DTC is detected>>GO TO 3.

Symptom is described, DTC is not detected>>GO TO 4.

Symptom is not described, DTC is detected>>GO TO 5.

3.

CONFIRM THE SYMPTOM

Try to confirm the symptom described by the customer (except MIL ON).

Also study the normal operation and fail-safe related to the symptom. Refer to 

EC-951, "Fuel Cut Control (at

No Load and High Engine Speed)"

 and 

EC-553, "Fail-Safe Chart"

.

Diagnosis Work Sheet is useful to verify the incident.

Verify relation between the symptom and the condition when the symptom is detected.

>> GO TO 5.

4.

CONFIRM THE SYMPTOM

Try to confirm the symptom described by the customer.

Also study the normal operation and fail-safe related to the symptom. Refer to Refer to 

EC-951, "Fuel Cut

Control (at No Load and High Engine Speed)"

 and 

EC-553, "Fail-Safe Chart"

.

Diagnosis Work Sheet is useful to verify the incident.

Verify relation between the symptom and the condition when the symptom is detected.

>> GO TO 6.

5.

PERFORM DTC CONFIRMATION PROCEDURE

Perform DTC CONFIRMATION PROCEDURE for the displayed DTC, and then check that DTC is detected

again.

If two or more DTCs are detected, refer to 

EC-555, "DTC Inspection Priority Chart"

 and determine trouble

diagnosis order.

NOTE:

• Freeze frame data is useful if the DTC is not detected.

• Perform Component Function Check if DTC CONFIRMATION PROCEDURE is not included on Service

Manual. This simplified check procedure is an effective alternative though DTC cannot be detected during

this check.

If the result of Component Function Check is NG, it is the same as the detection of DTC by DTC CONFIR-

MATION PROCEDURE.

Is DTC detected?

YES

>> GO TO 10.

NO

>> Check according to 

GI-37, "Intermittent Incident"

.

6.

PERFORM BASIC INSPECTION

Perform 

EC-592, "Basic Inspection"

.

Will CONSULT be used?

YES

>> GO TO 7.

NO

>> GO TO 9.

7.

PERFORM SPEC IN DATA MONITOR MODE

 With CONSULT

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DIAGNOSIS AND REPAIR WORK FLOW

Check that “MAS A/F SE-B1”, “MAS A/F SE-B2”, “B/FUEL SCHDL”, “A/F ALPHA-B1” and “A/F ALPHA-B2”

are within the SP value using “SPEC” in “DATA MONITOR” mode with CONSULT. Refer to 

EC-612, "Testing

Condition"

, 

EC-612, "Inspection Procedure"

.

Is the measurement value within the SP value?

YES

>> GO TO 9.

NO

>> GO TO 8.

8.

DETECT MALFUNCTIONING PART BY TROUBLE DIAGNOSIS - SPECIFICATION VALUE

Detect malfunctioning part according to 

EC-613, "Diagnosis Procedure"

.

Is a malfunctioning part detected?

YES

>> GO TO 11.

NO

>> GO TO 9.

9.

DETECT MALFUNCTIONING SYSTEM BY SYMPTOM TABLE

Detect malfunctioning system according to 

EC-947, "Symptom Matrix Chart"

 based on the confirmed symptom

in step 4, and determine the trouble diagnosis order based on possible causes and symptoms.

>> GO TO 10.

10.

DETECT MALFUNCTIONING PART BY DIAGNOSIS PROCEDURE

Inspect according to Diagnosis Procedure of the system.

NOTE:

The Diagnosis Procedure in EC section described based on open circuit inspection. A short circuit inspection

is also required for the circuit check in the Diagnosis Procedure. For details, refer to 

GI-40, "Circuit Inspec-

tion"

.

Is a malfunctioning part detected?

YES

>> GO TO 11.

NO

>> Monitor input data from related sensors or check voltage of related ECM terminals using CON-

SULT. Refer to 

EC-542, "CONSULT Reference Value in Data Monitor Mode"

, 

EC-545, "ECM Ter-

minal and Reference Value"

.

11.

REPAIR OR REPLACE THE MALFUNCTIONING PART

1. Repair or replace the malfunctioning part.

2. Reconnect parts or connectors disconnected during Diagnosis Procedure again after repair and replace-

ment.

3. Check DTC. If DTC is displayed, erase it.

>> GO TO 12.

12.

FINAL CHECK

When DTC was detected in step 2, perform DTC CONFIRMATION PROCEDURE or Component Function

Check again, and then check that the malfunction have been completely repaired.

When symptom was described from the customer, refer to confirmed symptom in step 3 or 4, and check that

the symptom is not detected.
Is DTC detected and does symptom remain?

YES-1 >> DTC is detected: GO TO 10.

YES-2 >> Symptom remains: GO TO 6.

NO-1 >> Before returning the vehicle to the customer, always erase unnecessary DTC in ECM and TCM

(Transmission Control Module). If the completion of SRT is needed, drive vehicle under the spe-

cific driving pattern. Refer to 

EC-600, "Description"

.

NO-2 >> I/M examination, requested from the customer: GO TO 13.

13.

PREPARE FOR I/M EXAMINATION

1. Set SRT codes. Refer to 

EC-600, "Description"

.

2. Erase permanent DTCs. Refer to 

EC-606, "Description"

.

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DIAGNOSTIC WORKSHEET

Description

There are many operating conditions that lead to the malfunction of

engine components. A good grasp of such conditions can make trou-

bleshooting faster and more accurate.

In general, each customer feels differently about a incident. It is

important to fully understand the symptoms or conditions for a cus-

tomer complaint.

Utilize a diagnostic worksheet like the one on the next page in order

to organize all the information for troubleshooting.

Some conditions may cause the MIL to come on steady or blink and

DTC to be detected. Examples:

• Vehicle ran out of fuel, which caused the engine to misfire.

• Fuel filler cap was left off or incorrectly screwed on, allowing fuel to

evaporate into the atmosphere.

Worksheet Sample

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EC-592

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INSPECTION AND ADJUSTMENT

INSPECTION AND ADJUSTMENT

Basic Inspection

INFOID:0000000007358456

1.

INSPECTION START

1. Check service records for any recent repairs that may indicate a related malfunction, or a current need for

scheduled maintenance.

2. Open engine hood and check the following:

-

Harness connectors for improper connections

-

Wiring harness for improper connections, pinches and cut

-

Vacuum hoses for splits, kinks and improper connections

-

Hoses and ducts for leakage

-

Air cleaner clogging

-

Gasket

3. Check that electrical or mechanical loads are not applied.

-

Headlamp switch is OFF.

-

Air conditioner switch is OFF.

-

Rear window defogger switch is OFF.

-

Steering wheel is in the straight-ahead position, etc.

4. Start engine and warm it up until engine coolant temperature

indicator points to the middle of gauge.

Check that engine stays below 1,000 rpm.

5. Run engine at approximately 2,000 rpm for approximately 2 min-

utes under no load.

6. Check that no DTC is displayed with CONSULT or GST.
OK or NG

OK

>> GO TO 3.

NG

>> GO TO 2.

2.

REPAIR OR REPLACE

Repair or replace components as necessary according to corresponding Diagnostic Procedure.

>> GO TO 3.

3.

CHECK TARGET IDLE SPEED

 With CONSULT

1. Run engine at approximately 2,000 rpm for approximately 2 minutes under no load.

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