Isuzu engine C22NE / 22LE / 20LE. Service manual — part 59

DRIVEABILITY AND EMISSIONS 6E1-65

Injector Coil Test Procedure (Steps 1-6) and

Injector Balance Test Procedure (Steps 7-11)

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

1. Turn the engine OFF.

Notice: In order to prevent flooding of a single cylinder

and possible engine damage, relieve the fuel pressure

before performing the fuel injector coil test procedure.

2. Relieve the fuel pressure. Refer to Test Description

Number 2.

3. Connect the 5-8840-2618-0 Fuel Injector Tester to B+

and ground, and to the 5-8840-2589-0 Injector Adapter

Cable.

4. Remove the harness connector of the Fuel Injector and

connect the 5-8840-2589-0 Injector Adapter Cable for

F/I check.

5. Set the amperage supply selector switch on the fuel

injector tester to the “Coil Test” 0.5 amp position.

6. Connect the leads from the 5-8840-2392-0 Digital

Voltmeter (DVM) to the fuel injector tester. Refer to the

illustrations associated with the test description.

7. Set the DVM to the tenths scale (0.0).

8. Observe the engine coolant temperature.

Is the engine coolant temperature within the specified

values?

10°C (50°F)

to

35°C (95°F)

Go to Step 3

Go to Step 5

3

1. Set the injector adapter cable to injector #1.

2. Press the “Push to Start Test” button on the fuel

injector tester.

3. Observe the voltage reading on the DVM.

Important: The voltage reading may rise during the test.

4. Record the lowest voltage observed after the first

second of the test.

5. Set the injector adapter cable to the next injector and

repeat steps 2, 3, and 4.

Did any fuel injector have an erratic voltage reading (large

fluctuations in voltage that did not stabilize) or a voltage

reading outside of the specified values?

5.7-6.6V

Go to Step 4

Go to Step 7

4

Replace the faulty fuel injector(S). Refer to Fuel Injector.

Is the action complete?

-

Go to Step 7

-

6E1-66 DRIVEABILITY AND EMISSIONS

Injector Coil Test Procedure (Steps 1-6) and

Injector Balance Test Procedure (Steps 7-11) (Cont'd)

Step

Action

Value(s)

Yes

No

5

1. Set the Injector Adapter Cable to injector #1.

2. Press the “Push to Start Test” button on the fuel

injector tester.

3. Observe the voltage reading on the DVM.

Important: The voltage reading may rise during the test.

4. Record the lowest voltage observed after the first

second of the test.

5. Set the Injector Adapter Cable to the next injector and

repeat steps 2, 3, and 4.

Did any fuel injector have an erratic voltage reading (large

fluctuations in voltage that did not stabilize) or a voltage

reading above the specified value?

9.5V

Go to Step 4

Go to Step 6

6

1. Identify the highest voltage reading recorded (other

than those above 9.5V).

2. Subtract the voltage reading of each injector from the

highest voltage selected in step 1. Repeat until you

have a subtracted value for each injector.

For any injector, is the subtracted value in step 2 greater

than the specified value?

0.6V

Go to Step 4

Go to Step 7

7

Caution: In order to reduce the risk of fire and

personal injury, wrap a shop towel around the fuel

pressure connection. The towel will absorb any fuel

leakage that occurs during the connection of the fuel

pressure gauge. Place the Towel in an approved

container when the connection of the fuel pressure

gauge is complete.

1. Connect the 5-8840-0378-0 Fuel Pressure Gauge to

the fuel pressure test port.

2. Energize the fuel pump using the Scan Tool.

3. Place the bleed hose of the fuel pressure gauge into an

approved gasoline container.

4. Bleed the air out of the fuel pressure gauge.

5. With the fuel pump running, observe the reading on the

fuel pressure gauge.

Is the fuel pressure within the specified values?

296kPa-

376kPa

(43-55psi)

Go to Step 8

Go to

Fuel System

Diagnosis

8

Turn the fuel pump OFF.

Does the fuel pressure remain constant?

-

Go to Step 9

Go to

Fuel System

Diagnosis

DRIVEABILITY AND EMISSIONS 6E1-67

Injector Coil Test Procedure (Steps 1-6) and

Injector Balance Test Procedure (Steps 7-11) (Cont'd)

Step

Action

Value(s)

Yes

No

9

1. Connect the 5-8840-0378-0 Fuel Injector Tester and

5-8840-2589-0 Injector Adapter Cable to the fuel

injector harness connector.

2. Set the amperage supply selector switch on the fuel

injector tester to the “Balance Test” 0.5-2.5 amp

position.

3. Using the Scan Tool turn the fuel pump ON then OFF

in order to pressurize the fuel system.

4. Record the fuel pressure indicated by the fuel

pressure gauge after the fuel pressure stabilizes.

This is the first pressure reading.

5. Energize the fuel injector by depressing the “Push to

Start Test” button on the fuel injector tester.

6. Record the fuel pressure indicated by the fuel

pressure gauge after the fuel pressure gauge needle

has stopped moving. This is the second pressure

reading.

7. Repeat steps 1 through 6 for each fuel injector.

8. Subtract the second pressure reading from the first

pressure reading for one fuel injector. The result is

the pressure drop value.

9. Obtain a pressure drop value for each fuel injector.

10. Add all of the individual pressure drop values.

This is the total pressure drop.

11. Divide the total pressure drop by the number of fuel

injectors. This is the average pressure drop.

Does any fuel injector have a pressure drop value that is

either higher than the average pressure drop or lower than

the average pressure drop by the specified value?

10kPa

(1.5psi)

Go to Step 10

Go to OBD

System

Check

10

Re-test any fuel injector that does not meet the

specification. Refer to the procedure in step 11.

Notice: Do not repeat any portion of this test before

running the engine in order to prevent the engine from

flooding.

Does any fuel injector still have a pressure drop value that

is either higher than the average pressure drop or lower

than the average pressure drop by the specified value?

10kPa

(1.5psi)

Go to Step 11

Go to

Symptoms

11

1. Replace the faulty fuel injector(s). Refer to Fuel

Injector.

2. Disconnect the 5-8840-2589-0 Injector Adapter Cable

for F/I check and re-connect the original F/I check

connector.

Is the action complete?

-

Verify repair

-

6E1-68 DRIVEABILITY AND EMISSIONS

ENGINE CONTROL MODULE

(ECM) DIAGNOSIS

To read and clear diagnostic trouble codes, use a

Scan Tool.

Important: Use of a Scan Tool is recommended to

clear diagnostic trouble codes from the ECM memory.

Diagnostic trouble codes can also be cleared by

turning the ignition OFF and disconnecting the battery

power from the ECM for 30 seconds. Turning off the

ignition and disconnecting the battery power from the

ECM will cause all diagnostic information in the ECM

memory to be cleared. Therefore, all the diagnostic

tests will have to be re-run.

Since the ECM can have a failure which may affect

only one circuit, following the diagnostic procedures in

this section will determine which circuit has a problem

and where it is.

If a diagnostic chart indicates that the ECM

connections or the ECM is the cause of a problem,

and the EPROM or ECM is replaced, but this does not

correct the problem, one of the following may be the

reason:
• There is a problem with the ECM terminal

connections. The terminals may have to be

removed from the connector in order to check them

properly.

• The problem is intermittent. This means that the

problem is not present at the time the system is

being checked. In this case, refer to the Symptoms

portion of the manual and make a careful physical

inspection of all components and wiring associated

with the affected system.

• There is a shorted solenoid, relay coil, or harness.

Solenoids and relays are turned ON and OFF by the

ECM using internal electronic switches called

drivers. A shorted solenoid, relay coil, or harness

will not damage the ECM but will cause the solenoid

or relay to be inoperative.

MULTIPLE ECM INFORMATION

SENSOR DTCs SET

Circuit Description

The engine control module (ECM) monitors various

sensors to determine the engine operating conditions.

The ECM controls fuel delivery, spark advance, and

emission control device operation based on the sensor

inputs.

The ECM provides a sensor ground to all of the

sensors. The ECM applies 5 volts through a pull-up

resistor, and determines the status of the following

sensors by monitoring the voltage present between

the 5-volt supply and the resistor:
• The throttle position (TP) sensor
• The manifold absolute pressure (MAP) sensor
The ECM provides the following sensors with a 5-volt

reference and a sensor ground signal:
• Intake Air Temp Sensor (IAT).
• Engine Coolant Temp Sensor (ECT).
• Manifold Absolute Pressure Sensor (MAP).
• Throttle Position Sensor (TPS).
The ECM monitors the separate feedback signals

from these sensors in order to determine their

operating status.