Isuzu D-Max / Isuzu Rodeo (TFR/TFS). Service manual - part 212

ENGINE DRIVEABILITY AND EMISSIONS

6E–89

2

Using the DVM and check the “CHECK ENGINE”
lamp circuit.

1. Ignition “Off”, engine “Off”. 

2. Disconnect the meter connector and ECM

connector. 

3. Check the circuit for short to ground circuit. 

Was the problem found?

—

Verify repair

Go to Step 3

3

Replace the meter assembly. 
Is the action complete?

—

Verify repair

—

4

Is the ECM programmed with the latest software
release? 
If not, download the latest software to the ECM using
the “SPS (Service Programming System)”. 
Was the problem solved?

—

Verify repair

Go to Step 5

5

Replace the ECM. 
Is the action complete? 
IMPORTANT:  The replacement ECM must be
programmed. Refer to section of the Service
Programming System (SPS) in this manual. 
Following ECM programming, the immobiliser system
(if equipped) must be linked to the ECM. Refer to
section 11 “Immobiliser System-ECM replacement” for
the ECM/Immobiliser linking procedure.

—

Verify repair

—

Step

Action

Value(s)

Yes

No

32

C56(J2)

6E–90

ENGINE DRIVEABILITY AND EMISSIONS

FUEL METERING SYSTEM CHECK

Some failures of the fuel metering system will result in
an  “Engine Cranks But Will Not Run” symptom. If this
condition exists, refer to the Cranks But Will Not Run
chart. This chart will determine if the problem is caused
by the ignition system, the ECM, or the fuel pump
electrical circuit.
Refer to Fuel System Electrical Test for the fuel system
wiring schematic.
If there is a fuel delivery problem, refer to Fuel System
Diagnosis, which diagnoses the fuel injectors, the fuel
pressure regulator, and the fuel pump. 
Followings are applicable to the vehicles with
closed Loop System:
If a malfunction occurs in the fuel metering system, it
usually results in either a rich HO2S signal or a lean
HO2S signal. This condition is indicated by the HO2S
voltage, which causes the ECM to change the fuel
calculation (fuel injector pulse width) based on the
HO2S reading. Changes made to the fuel calculation
will be indicated by a change in the long term fuel trim
values which can be monitored with a Scan Tool. Ideal
long term fuel trim values are around 0%; for a lean
HO2S signal, the ECM will add fuel, resulting in a fuel
trim value above 0%. Some variations in fuel trim values
are normal because all engines are not exactly the
same. If the evaporative emission canister purge is 02
status may be rich condition. 02 status indicates the
lean condition, refer to DTC P1171 for items which can
cause a lean HO2S signal.

FUEL INJECTOR COIL TEST PROCEDURE 
AND FUEL INJECTOR BALANCE TEST 
PROCEDURE

Test Description

Number(s) below refer to the step number(s) on the
Diagnostic Chart:
2. Relieve the fuel pressure by connecting 5-8840-

0378-0 T-Joint to the fuel pressure connection on the
fuel rail.

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.
Place the fuel pressure gauge bleed hose in an
approved gasoline container.
With the ignition switch OFF open the valve on the
fuel pressure gauge.

3. Record the lowest voltage displayed by the DVM

after the first second of the test. (During the first
second, voltage displayed by the DVM may be
inaccurate due to the initial current surge.)
Injector Specifications:

• The voltage displayed by the DVM should be

within the specified range.

• The voltage displayed by the DVM may increase

throughout the test as the fuel injector windings
warm and the resistance of the fuel injector
windings changes.

Resistance Ohms

Voltage Specification at 
10°C-35°C (50°F-95°F)

11.8-12.6

5.7-6.6

ENGINE DRIVEABILITY AND EMISSIONS

6E–91

• An erratic voltage reading (large fluctuations in

voltage that do not stabilize) indicates an
intermittent connection within the fuel injector.

5. Injector Specifications:

7.  The Fuel Injector Balance Test portion of this chart

(Step 7 through Step 11) checks the mechanical
(fuel delivery) portion of the fuel injector. An engine
cooldown period of 10 minutes is necessary in order
to avoid irregular fuel pressure readings due to “Hot
Soak” fuel boiling.

Injector Coil Test Procedure (Steps 1-6) and Injector Balance Test Procedure (Steps 7-11)

NOTE:  These figures are examples only.

Highest Acceptable Voltage

Reading Above/Below

35°C/10°C (95°F/50°F)

Acceptable  

Subtracted Value

9.5Volts

0.6Volt

CYLINDER

1

2

3

4

1st Reading (1)

296kPa

(43psi)

296kPa

(43psi)

296kPa

(43psi)

296kPa

(43psi)

2nd Reading (2)

205kPa

(29psi)

205kPa

(29psi)

196kPa

(28psi)

274kPa

(39psi)

Amount of Drop

(1st Reading-2nd Reading)

91kPa

(14psi)

91kPa

(14psi)

100kPa

(15psi)

22kPa

(4psi)

Av. Drop = 166kPa/24psi

±10kPa/1.5psi

= 156 - 176kPa or

22.5 - 25.5psi

Faulty, Lean

(Too Little Fuel 

Drop)

Faulty, Lean

(Too Little Fuel 

Drop)

Faulty, Lean

(Too Little Fuel 

Drop)

Faulty, Lean

(Too Little Fuel 

Drop)

6E–92

ENGINE DRIVEABILITY AND EMISSIONS

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.

NOTE: 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

—