2007 ISUZU KB P190 Circuit

6E–94 ENGINE DRIVEABILITY AND EMISSIONS
NO CHECK ENGINE LAMP (MIL)
Circuit Description
The check engine lamp should be illuminated and
steady for about five seconds with the ignition “ON” and
the engine stopped. Ignition feed voltage is supplied to
the check engine lamp bulb through the meter fuse.
The Engine Control Module (ECM) turns the check
engine lamp “ON” by grounding the check engine lamp
driver circuit.
Diagnostic Aids
An intermittent check engine lamp may be cased by a
poor connection, rubbed-through wire insulation, or a wire broken inside the insulation. Check for the
following items:
• Inspect the ECM harness and connections for improper mating, broken locks, improperly formed or
damaged terminals, poor terminal-to-wire connection,
and damaged harness.
• If the engine runs OK, check for a faulty light bulb, an open in the check engine lamp driver circuit, or an
open in the instrument cluster ignition feed.
• If the engine cranks but will not run, check for an open ECM ignition or battery feed, or a poor ECM to
engine ground.
No Check Engine Lamp (MIL)
Step Action Value(s) Yes No
1 Check the “Meter” fuse (15A). If the fuse is burnt out, repair as necessary.
Was the problem found? — Verify repair Go to Step 2

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ISUZU KB P190 2007

ENGINE DRIVEABILITY AND EMISSIONS 6E–95
2 Using the DVM and check the “CHECK ENGINE”lamp circuit.
1. Ignition “Off”, engine “Off”.
2. Disconnect the ECM connector.
3. Ignition “On”.
4. Check the circuit for open circuit.
Was the DVM indicated specified value?
10 - 14.5V Go to Step 5Go to Step 3
3 Check the “CHECK ENGINE” lamp bulb. If the bulb is burnt out, repair as necessary.
Was the problem found? — Verify repair Go to Step 4
4 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 open circuit.
Was the problem found?
— Verify repair Go to Step 5
5 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 6
6 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 immobilizer system
(if equipped) must be linked to the ECM. Refer to
section 11 “Immobilizer System-ECM replacement” for
the ECM/Immobilizer linking procedure. — Verify repair —
Step
Action Value(s) Yes No
V
32C56(J2)
3217C56(J2)B24

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ISUZU KB P190 2007

6E–96 ENGINE DRIVEABILITY AND EMISSIONS
CHECK ENGINE LAMP (MIL) “ON” STEADY
Circuit description
The check engine lamp should always be illuminated
and steady for about five seconds with ignition “ON” and
the engine stopped. Ignition feed voltage is supplied
directly to the check engine lamp indicator. The Engine
Control Module (ECM) turns the check engine lamp
“ON” by grounding the check engine lamp driver circuit.
The check engine lamp should not remain “ON” with the
engine running and no DTC(s) set. A steady check
engine lamp with the engine running and no DTC(s)
suggests a short to ground in the check engine lamp
driver circuit.
Diagnostic Aids
An intermittent 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.
Check Engine Lamp (MIL) “ON” Steady
Step Action Value(s) Yes No
1 1. Ignition “Off”, engine “Off”. 2. Disconnect the ECM connector.
3. Ignition “On”.
Was the “CHECK ENGINE” lamp turned on? — Go to Step 2Go to Step 4

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ISUZU KB P190 2007

ENGINE DRIVEABILITY AND EMISSIONS 6E–97
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 immobilizer system
(if equipped) must be linked to the ECM. Refer to
section 11 “Immobilizer System-ECM replacement” for
the ECM/Immobilizer linking procedure. — Verify repair —
Step
Action Value(s) Yes No
32C56(J2)

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ISUZU KB P190 2007

6E–98 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

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ENGINE DRIVEABILITY AND EMISSIONS 6E–103
FUEL SYSTEM ELECTRICAL TEST
Circuit Description
When the ignition switch is first turned ON, the engine
control module (ECM) energizes the fuel pump relay
which applies power to the in-tank fuel pump. The fuel
pump relay will remain ON as long as the engine is
running or cranking and the ECM is receiving 58X
crankshaft position pulses. If no 58X crankshaft position
pulses are present, the ECM de-energizes the fuel
pump relay within 2 seconds after the ignition is turned
ON or the engine is stopped.
The fuel pump delivers fuel to the fuel rail and injectors,
then to the fuel pressure regulator. The fuel pressure
regulator controls fuel pressure by allowing excess fuel
to be returned to the fuel tank. With the engine stopped
and ignition ON, the fuel pump can be turned ON by
using a command by the scan tool.
Diagnostic Aids
An intermittent 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. Caution: To reduce the risk of fire and personal
injury:
• It is necessary to relieve fuel system pressure before connecting a fuel pressure gauge.
Refer to Fuel Pressure Relief Procedure,
below.
• A small amount of fuel may be released when disconnecting the fuel lines. Cover fuel line
fittings with a shop towel before
disconnecting, to catch any fuel that may leak
out. Place the towel in an approved container
when the disconnect is completed.

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ISUZU KB P190 2007

ENGINE DRIVEABILITY AND EMISSIONS 6E–105
6 Using the DVM and check the fuel pump relay powersupply circuit.
1. Ignition “On”, engine “Off”.
2. Remove the fuel pump relay from the relay box.
3. Check the circuit for open or short to ground circuit.
Was the DVM indicated specified value?
10 - 14.5V Go to Step 8Go to Step 7
7 Repair the open or short to ground circuit between the “ECM” fuse (15A) and fuel pump relay.
Is the action complete? — Verify repair —
8 Using the DVM and check the fuel pump relay ground circuit.
1. Ignition “Off”, engine “Off”.
2. Disconnect the ECM connector.
3. Remove the fuel pump relay from the relay box.
4. Check the circuit for open or short to ground circuit.
Was the problem found?
—Repair faulty
harness and verify repair Go to Step 9
9 Using the DVM and check the fuel pump relay power supply circuit.
1. Ignition “Off”, engine “Off”.
2. Remove the fuel pump relay from the relay box.
3. Check the circuit for open circuit.
Was the DVM indicated specified value?
10 - 14.5V Go to Step 11Go to Step 10
Step
Action Value(s) Yes No
V
3
X2
4
11C56(J2)X2
V
1X2

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6E–106 ENGINE DRIVEABILITY AND EMISSIONS
10 Repair the open circuit between the fuel pump relayand battery.
Is the action complete? — Verify repair —
11 Using the DVM and check the fuel pump power supply circuit.
1. Ignition “On”, engine “Off”.
2. Disconnect the fuel pump connector.
3. Check the circuit for open or short to ground circuit.
Was the DVM indicated specified value?
10 - 14.5V Go to Step 13Go to Step 12
12 Repair the open or short to ground circuit between the fuel pump relay and fuel pump.
Is the action complete? — Verify repair —
13 Using the DVM and check the fuel pump ground circuit.
1. Ignition “Off”, engine “Off”.
2. Disconnect the fuel pump connector.
3. Check the circuit for open circuit.
Was the DVM indicated specified value?
Continuity Go to Step 15Go to Step 14
14 Repair the open circuit between the fuel pump and body ground.
Is the action complete? — Verify repair —
15 Replace the fuel pump. Was the problem solved? — Verify repair Go to Step 16
16 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 17
Step
Action Value(s) Yes No
V
1
F2
F-2
Ω
4

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ISUZU KB P190 2007