Isuzu engine C22NE / 22LE / 20LE. Service manual — part 69

DRIVEABILITY AND EMISSIONS 6E1-105

DEFAULT MATRIX TABLE

SERVICE PROCEDURE DEFAULT STRATEGY

A referral strategy has been established to assist the

technician with additional information when the cause

of the failure cannot be determined. If no problem is

found after performing diagnostics, then refer to the

default matrix table for further diagnostic information.

Default Matrix Table

Strategy Based

Diagnostic Charts

Initial Diagnosis

Default Section(s)

On-Board Diagnostic

(OBD) System Check

Vehicle does not enter diagnostics.

Chassis Electrical

On-Board Diagnostic

(OBD) System Check

Vehicle enters diagnostics and communicates

with the Scan Tool.

MIL is ON in diagnostics. Engine does not start

and run.

Ignition System Check

On-Board Diagnostic

(OBD) System Check

Engine starts and runs, no ECM codes set.

Customer complains of vibration.

-

ECM Power and Ground

Check

On-Board Diagnostic (OBD) System Check.

Chassis Electrical

ECM Power and Ground

Check

On-Board Diagnostic (OBD) System Check.

ECM power and ground circuits OK. Data link

voltage incorrect.

Chassis Electrical

Symptoms

Initial Diagnosis

Default Section(s)

Intermittens

1. On-board diagnostic (OBD) system check.

2. Careful visual/physical inspections.

Chassis Electrical

Hard Starts

1. OBD system check.

2. Sensors (ECT, MAP, TP); MAP output chart.

3. Fuel system electrical test, fuel system

diagnosis.

4. Ignition system.

5. IAC system check.

Engine Mechanical, Ignition System

Check, Exhaust System Diagnosis

Surges and/or Chuggles

1. OBD system check.

2. Heated oxygen sensors (If applicable).

3. Fuel system diagnosis.

4. Ignition system.

Calibration ID "Broadcast Code"

/Service Bulletins, Ignition System

Check, Generator Output, Exhaust

System Diagnosis

6E1-106 DRIVEABILITY AND EMISSIONS

Default Matrix Table (Cont'd)

Strategy Based

Diagnostic Charts

Initial Diagnosis

Default Section(s)

Lack of Power, Sluggish

or Spongy

1. OBD system check.

2. Fuel system diagnosis.

3. Ignition system.

Refer to Exhaust System in Engine

Exhaust, Calibration ID/Service

Bulletins

Detonation/Spark Knock

1. OBD system check.

2. Fuel system diagnosis.

3. Ignition system.

Cooling System, Ignition System

Check, Calibration ID/Service

Bulletins

Hesitation, Sag, Stumble

1. OBD system check.

2. TP.

3. MAP output check.

4. Fuel system diagnosis.

5. Fuel injector and fuel injector balance test.

6. EVAP emission canister purge control

solenoid valve (If applicable).

7. Ignition system.

Generator Output Voltage (refer to

Chassis Electrical), Calibration

ID/Service Bulletins, Ignition System

Check

Cuts Out, Misses

1. OBD system check.

2. Cylinder balance test.

Ignition System Check

Rough, Unstable, or

Incorrect Idle, Stalling

1. OBD system check.

2. Fuel injector and fuel injector balance test.

3. EVAP emission canister purge control

solenoid valve check (If applicable).

4. Ignition system.

5. IAC operation.

MAP Output Check, Throttle

Linkage, IAC System Check, A/C

Clutch Control Circuit Diagnosis,

Crankcase Ventilation System,

Calibration ID/Service Bulletins,

Generator Output Voltage (refer to

Chassis Electrical), Exhaust

Diagnosis

Poor Fuel Economy

1. OBD system check.

2. Careful visual/physical inspection.

3. Ignition system.

4. Cooling system.

Exhaust System (refer to Engine

Exhaust)

Engine Cranks But Will

Not Run

1. OBD system check.

Fuel System Electrical Diagnosis,

Fuel System Diagnosis, Fuel

Injector and Fuel Injector Balance

Test.

Excessive Exhaust

Emissions or Odors

1. OBD system check.

2. Emission test.

3. Cooling system.

4. Fuel system diagnosis.

5. Fuel injector and fuel injector balance test.

6. EVAP emission canister purge control

solenoid valve (If applicable).

7. Crankcase ventilation system.

8. Ignition system.

9. MAP output check.

Exhaust Diagnosis, Calibration

ID/Service Bulletins

Dieseling, Run-On

1. OBD system check.

2. Careful visual/physical inspection.

3. Fuel system diagnosis.

-

DRIVEABILITY AND EMISSIONS 6E1-107

Default Matrix Table (Cont'd)

Strategy Based

Diagnostic Charts

Initial Diagnosis

Default Section(s)

Backfire

1. OBD system check.

2. Ignition system.

3. Fuel system diagnosis.

4. Fuel injector and fuel injector balance test.

Exhaust System Diagnosis, Intake

Casting Flash, Ignition System

Check

Misfire

1. OBD system check.

2. Ignition system.

3. Fuel system diagnosis.

4. Fuel injector and fuel injector balance test.

Vibrations, Transmission,

Driveshaft and Axle

Catalyst Monitor

1. OBD system check.

2. Careful visual/physical inspection.

3. Heated oxygen sensors. (If applicable)

Exhaust System

Fuel Trim

1. OBD system check.

2. Careful visual/physical inspection.

3. Fuel system diagnosis.

4. Heated oxygen sensors. (If applicable)

Exhaust System Intake Air System

Evaporative Emissions

(If applicable)

1. OBD system check.

2. Careful visual/physical inspection.

3. Fuel system diagnosis.

-

Heated Oxygen Sensors

(If applicable)

1. OBD system check.

2. Careful visual/physical inspection.

Exhaust System

6E1-108 DRIVEABILITY AND EMISSIONS

ENGINE CRANKS BUT WILL NOT RUN

Circuit Description

The electronic ignition system uses a dual coil method

of spark distribution. In this type of ignition system, the

engine control module (ECM) triggers the correct

driver inside the ECM, which then triggers the correct

ignition timing based on the 58X signal received from

the crankshaft position sensor (CKP). The spark plug

connected to the coil fires when the coildriver opens

the ground circuit for the coil's primary circuit.

During crank, the ECM monitors the CKP 58X signal.

The CKP signal is used to determine which cylinder

will fire first. After the CKP 58X signal has been

processed by the ECM, the four injectors are divided

into two groups, one is composed of #1 and #4

cylinders, the other group, #2 and #3 cylinders.

58X signal is processed by ECM and it issues the

following command to each group at every turn of the

crankshaft.

To jet a half amount of the fuel required for a single

combustion stroke to each cylinder.

Diagnostic Aids

An intermittent problem may be caused by a poor

connection, rubbed-through wire insulation or a wire

broken inside the insulation. Check for the following

items:
• Poor connection or damaged harness - Inspect the

ECM harness and connectors for improper mating,

broken locks, improperly formed or damaged

terminals, poor terminal-to-wire connection, and

damaged harness.

• Faulty engine coolant temperature sensor - Using a

scan tool, compare engine coolant temperature with

intake air temperature on a completely cool engine.

Engine coolant temperature should be within 10°C

of intake air temperature. If not, replace the ECT

sensor.

Engine Cranks But Will Not Run

Step

Action

Value(s)

Yes

No

1

Was the “On-Board Diagnostic (OBD) System

Check” performed?

-

Go to Step 2

Go to OBD

System

Check

2

Use the Scan Tool and check for any DTC's.

Are any DTC's stored?

-

Go to

Applicable

DTC Table

Go to Step 3

3

Check the 15A ignition coil fuse, the 15A engine device

fuse, and the 15A ECM fuse.

Was a fuse blown?

-

Go to Step 4

Go to Step 5

4

Check for a short to ground and replace the fuse.

Is the action complete?

-

Verify repair

-

5

1. Ignition ON

2. Use a grounded test lamp to verify that B+ is available

at the ignition coil fuse, the engine device fuse, and the

ECM fuse.

3. Was B+ available at the fuses?

-

Go to Step 7

Go to Step 6

6

Repair the open ignition feed circuit.

-

Go to

Fuel System

Electrical

Test

Go to

Fuel System

Diagnosis