2007 ISUZU KB P190 relay

ENGINE CONTROL SYSTEM (4JK1/4JJ1) 6E-53
Cam/ Crank Sensor Signal/ Synchronization Status
This parameter displays the synchronization state of
the crankshaft position (CKP) sensor signal and
camshaft position (CMP) sensor signal. Asynchronous
indicates the CMP sensor signal is not detected or only
CKP sensor signal is detected. No Crank Signal
indicates CMP sensor signal is detected but CKP
sensor signal is not detected. Synchronous indicates
both sensor signals are detected correctly.
Engine Runtime
This parameter displays the time elapsed since the
engine start. The scan tool will display the time in
hours, minutes and seconds. The engine run time will
reset to zero as soon as the ignition switch is OFF.
Vehicle Speed
This parameter indicates the vehicle speed calculated
by the ECM using the signal from the vehicle speed
sensor (VSS). The scan tool will display a low value at
lower vehicle speeds, and a high value at higher
vehicle speeds.
Transmission Gear
This parameter displays the estimated transmission
gear position as calculated by the ECM based on
inputs from the vehicle speed and the engine speed.
Starter Switch
This parameter displays the input status of the starter
switch to the ECM. When the ignition switch is turned at
START position, the scan tool displays On.
Ignition Switch
This parameter displays the input status of the ignition
switch to the ECM. When the ignition switch is turned
ON position, the scan tool displays On.
Ignition Voltage
This parameter displays the ignition voltage measured
at the ignition feed circuit of the ECM. Voltage is
applied to the ECM when the ignition switch is ON
position.
Battery Voltage
This parameter displays the battery voltage measured
at the ECM main relay switched voltage feed circuit of
the ECM. Voltage is applied to the ECM when the ECM
main relay is energized.
Fuel Pump Relay Command
This parameter displays the commanded state of the
fuel pump relay control circuit. On indicates the fuel
pump relay control circuit is being grounded by the
ECM, allowing fuel pumping from the tank.
Swirl Control Solenoid Command
This parameter displays the commanded state of the
swirl control solenoid control circuit. On indicates the
swirl control solenoid control circuit is being grounded
by the ECM, allowing vacuum pressure to the swirl
control
actuator. Fuel Filter Switch
This parameter displays the input state of the fuel
pressure switch to the ECM. When the large vacuum
pressure is generated in the fuel suction line such as
clogged fuel filter, the scan tool displays Off.
A/C Request Signal
This parameter displays the input state of the air
conditioning (A/C) request to the ECM from the
heating, ventilation, and air conditioning (HVAC)
controls. When the HVAC system is requesting to
ground the A/C compressor clutch, the scan tool
displays On.
A/C Relay Command
This parameter displays the commanded state of the A/
C compressor relay control circuit. On indicates the A/C
compressor relay control circuit is being grounded by
the ECM, allowing voltage to the A/C compressor.
Park/ Neutral Switch
This parameter displays the input state of the neutral
switch to the ECM. When the transmission gear is Park
or Neutral, the scan tool displays Neutral.
Glow Relay Command
This parameter displays the commanded state of the
glow relay control circuit. On indicates the glow relay
control circuit is being grounded by the ECM, allowing
voltage to the glow plugs.
Glow Plug Lamp Command
This parameter displays the commanded state of the
glow indicator lamp control circuit. The glow indicator
lamp should be On when the scan tool indicates
command On. The glow indicator lamp should be Off
when the scan tool indicates command Off.
Brake Switch 1
This parameter displays the input state of the brake
pedal switch 1 to the ECM. When the brake pedal is
depressed, scan tool displays Applied.
Brake Switch 2
This parameter displays the input state of the brake
pedal switch 2 to the ECM. When the brake pedal is
depressed, scan tool displays Applied.
Clutch Pedal Switch
This parameter displays the input state of the clutch
pedal switch to the ECM. When the clutch pedal is
depressed, scan tool displays Applied.
Cruise Main Lamp Command
This parameter displays the commanded state of the
cruise main lamp control circuit. The cruise main lamp
should be On when the scan tool indicates command
On. The cruise main lamp should be Off when the scan
tool indicates command Off.
Cruise Main Switch
This parameter displays the input state of the cruise
main switch to the ECM. When the Cruise Main switch
is pushed, the scan tool displays On.

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ISUZU KB P190 2007

ENGINE CONTROL SYSTEM (4JK1/4JJ1) 6E-55
Scan Tool Output Controls
Scan Tool Output ControlDescriptions
Fuel Supply Pump Learn Resetting The purpose of this test to reset the fuel supply pump adjustment value.
Important: The fuel supply pump relearn procedure must be done when the fuel supply
pump or engine is replaced, or an ECM from another vehicle is installed. Refer to Fuel
Supply Pump Replacement.
Fuel Pressure Control The purpose of this test is for checking whether the fuel rail pressure is changing when
commanded within 30 to 80MPa (4,350 to 11,600psi) when commanded. Faulty fuel supply
pump, fuel rail pressure (FRP) regulator, pressure limiter valve or other fuel lines could be
considered if the differential fuel rail pressure is large.
Pilot Injection Control The purpose of this test is for checking whether the pilot fuel injection is operated when it is
commanded to ON/ OFF. Faulty injector(s) could be considered if engine noise does not
change when commanded OFF.
Injection Timing Control The purpose of this test is for checking whether the main injection timing is changing when
commanded Retard/ Advance within -5 to 5 °CA.
Injector Force Drive The purpose of this test is for checking whether the fuel injector is correctly operating when
commanded ON. Faulty injector(s) could be considered if it does not create a clicking noise
(solenoid operating noise), contains an interrupted noise or has abnormal noise when
commanded ON.
Cylinder Balance Test The purpose of this test is for checking whether the fuel injector is operating when
commanded ON/ OFF. Faulty injector(s) could be considered if engine does not change
speed when commanded OFF.
Intake Throttle Solenoid Control The purpose of this test is for checking whether the intake throttle valve is correctly moved
with command. Restricted valve movement by foreign materials, excessive deposits or a
faulty valve could be considered if the position difference is large.
EGR Solenoid Control The purpose of this test is for checking whether the EGR valve is correctly moved with
command. Restricted valve movement by foreign materials, excessive deposits or a faulty
valve could be considered if the position difference is large.
Swirl Control Solenoid Control The purpose of this test is for checking whether the swirl control solenoid is operating when
commanded ON. Faulty circuit(s) or a faulty solenoid could be considered if not energizing
when commanded ON.
Turbocharger Solenoid Control The purpose of this test is for checking whether the turbocharger nozzle control actuator is
correctly moved with command. Restricted actuator movement by foreign materials,
excessive deposits, misrouted vacuum hoses, a faulty solenoid or a faulty actuator could be
considered if the actuator is not moved correctly.
Glow Relay Control The purpose of this test is for checking whether the glow relay is operating when
commanded ON. Faulty circuit(s) or a faulty glow relay could be considered if not energizing
when commanded ON.
Glow Plug Lamp Control The purpose of this test is for checking whether the glow indicator lamp is operating when
commanded ON. Faulty circuit(s) or an open circuit could be considered when not operating
when commanded ON.
Malfunction Indicator Lamp (MIL) Control The purpose of this test is for checking whether the MIL is operating when commanded ON.
Faulty circuit(s) or an open circuit could be considered when not operating when
commanded ON.
Service Vehicle Soon (SVS) Lamp Control The purpose of this test is for checking whether the SVS lamp is operating when
commanded ON. Faulty circuit(s) or an open circuit could be considered when not operating
when commanded ON.
Cruise Main Lamp Control The purpose of this test is for checking whether the cruise main lamp is operating when
commanded ON. Faulty circuit(s) or an open circuit could be considered when not operating
when commanded ON.
Cruise Set Lamp Control The purpose of this test is for checking whether the cruise set lamp is operating when
commanded ON. Faulty circuit(s) or an open circuit could be considered when not operating
when commanded ON.

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ISUZU KB P190 2007

ENGINE CONTROL SYSTEM (4JK1/4JJ1) 6E-61
71. Check ECM ground for corrosion and
tightness.
2. Clean or tighten grounds as necessary.
Did you find and correct the condition? —
Go to Step 16 Go to Step 8
8 1. Turn OFF the ignition.
2. Reconnect the ECM harness connector if disconnected.
3. Replace the ECM main relay with the heater relay or replace with a known good relay.
4. Turn ON the ignition, with the engine OFF.
5. Attempt to establish communication with the ECM.
Does the scan tool communicate with the ECM? —
Go to Step 14 Go to Step 9
9 1. Turn OFF the ignition.
2. Remove the ECM main relay.
3. Turn ON the ignition, with the engine OFF.
4. Using a test lamp, check for both voltage supply circuits to the ECM main relay (pins 4
and 5 of X-12).
5. Repair the open circuit(s) as necessary.
Did you find and correct the condition? —
Go to Step 16 Go to Step 10
10 1. Reinstall the ECM main relay.
2. Turn the ignition ON and OFF while listening of feeling for the ECM main relay click. Wait 7
seconds between transitions.
Does the ECM main relay click when the ignition
switch is turned ON or OFF? —
Go to Step 12 Go to Step 11
11 Repair the ECM main relay ground circuit between
the ECM main relay (pin 2 of X-12) and engine
room ground terminal (C-36) for the following
conditions: •An open circuit
• High resistance or a poor connection at the
ECM main relay or ground terminal
Did you complete the repair? —
Go to Step 16
—
121. Test the battery voltage circuit between the
ECM (pin 73 of C-58) and the ECM main relay
(pin 1 of X-12) for the following conditions:
• An open circuit
• High resistance or a poor connection at ECM or ECM main relay
2. Repair the circuit(s) as necessary.
Did you find and correct the condition? —
Go to Step 16 Go to Step 15
13 Repair the open in the ignition voltage circuit to the
ECM.
Did you complete the repair? —
Go to Step 16
—
14Replace the ECM main relay.
Did you complete the replacement? —
Go to Step 16—
Step Action Value(s)Yes No

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ISUZU KB P190 2007

6E-62 ENGINE CONTROL SYSTEM (4JK1/4JJ1)
15Important
: Replacement ECM must be
programmed and learned.
Replace the ECM. Refer to ECM Replacement.
Did you complete the replacement? —
Go to Step 16
—
161. Turn OFF the ignition.
2. Reconnect all previously disconnected fuse, relay or harness connector(s).
3. Turn ON the ignition, with the engine OFF.
4. Attempt to establish communication with the ECM.
Does the scan tool communicate with the ECM? —
System OK Go to Step 3
Step
Action Value(s)Yes No

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ISUZU KB P190 2007

ENGINE CONTROL SYSTEM (4JK1/4JJ1) 6E-99
31. Turn OFF the ignition.
2. Disconnect the MAF sensor harness connector.
3. Connect a test lamp between the ignition voltage feed circuit (pin 1 of E-47) and a
known good ground.
4. Turn ON the ignition, with the engine OFF.
Does the test lamp illuminate? —
Go to Step 4 Go to Step 5
4 1. Turn OFF the ignition for 30 seconds.
2. Connect a 3-amp fused jumper wire between the ignition voltage feed circuit and the signal
circuit (pins 1 and 3 of E-47).
3. Turn ON the ignition, with the engine OFF.
Is the MAF Sensor parameter more than the
specified value? 4.9 volts
Go to Step 7 Go to Step 6
5 Repair the open circuit or high resistance between
the ECM Main Relay (pin 1 of X-12) and the MAF
sensor (pin 1 of E-47) for and open circuit or high
resistance. Check the Engine (10A) fuse first.
Did you complete the repair? —
Go to Step 11
—
61. Test the signal circuit between the ECM (pin
40 of E-90) and the MAF sensor (pin 3 of E-
47) for the following conditions:
• An open circuit
• A short to ground
• A short to the low reference circuit
• High resistance
2. Repair the circuit(s) as necessary.
Did you find and correct the condition? —
Go to Step 11 Go to Step 8
7 1. Inspect for an intermittent and for poor
connections at the harness connector of the
MAF sensor (pins 1 and 3 of E-47).
2. Repair the connection(s) as necessary.
Did you find and correct the condition? —
Go to Step 11 Go to Step 9
8 1. Turn OFF the ignition.
2. Disconnect the ECM harness connector.
3. Inspect for an intermittent and for a poor connection at the harness connector of the
ECM (pin 40 of E-90).
4. Repair the connection(s) as necessary.
Did you find and correct the condition? —
Go to Step 11 Go to Step 10
9 Replace the MAF sensor. Refer to MAF Sensor
Replacement.
Did you complete the replacement? —
Go to Step 11
—
10Important:
Replacement ECM must be
programmed and learned.
Replace the ECM. Refer to ECM Replacement.
Did you complete the replacement? —
Go to Step 11
—
Step Action Value(s)Yes No

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ISUZU KB P190 2007

6E-100 ENGINE CONTROL SYSTEM (4JK1/4JJ1)
Circuit/ System Testing DTC P0103
111. Reconnect all previously disconnected fuse,
relay or harness connector(s).
2. Clear the DTCs with a scan tool.
3. Turn OFF the ignition for 30 seconds.
4. Start the engine.
5. Operate the vehicle within the Conditions for Running the DTC. You may also operate the
vehicle within the conditions that you
observed from the Freeze Frame/ Failure
Records.
Did the DTC fail this ignition? —
Go to Step 2 Go to Step 12
12 Observe the DTC Information with a scan tool.
Are there any DTCs that you have not diagnosed? —
Go to DTC List System OK
Step
Action Value(s)Yes No
Step Action Value(s)Yes No
1 Did you perform the Diagnostic System Check -
Engine Controls? —
Go to Step 2 Go to Diagnostic
System Check -
Engine Controls
2 1. Install a scan tool.
2. Turn OFF the ignition for 30 seconds.
3. Start the engine.
4. Observe the Mass Air Flow (MAF) Sensor parameter with a scan tool.
Is the MAF Sensor parameter more than the
specified value? 4.9 volts
Go to Step 3 Go to Diagnostic
Aids
3 1. Turn OFF the ignition for 30 seconds.
2. Disconnect the MAF sensor harness connector.
3. Turn ON the ignition, with the engine OFF.
Is the MAF Sensor parameter less than the
specified value? 0.1 volts
Go to Step 4 Go to Step 5
4 Connect a test lamp between the low reference
circuit (pin 2 of E-47) and battery voltage.
Does the test lamp illuminate? —
Go to Step 7 Go to Step 6
5 1. Test the signal circuit between the ECM (pin
40 of E-90) and the MAF sensor (pin 3 of E-
47) for the following conditions:
• A short to battery or ignition voltage
• A short to any 5 volts reference
2. Repair the circuit(s) as necessary.
Did you find and correct the condition? —
Go to Step 11 Go to Step 10
6 1. Test the low reference circuit between the
ECM (pin 43 of E-90) and the MAF sensor (pin
2 of E-47) for an open circuit or high
resistance.
2. Repair the circuit(s) as necessary.
Did you find and correct the condition? —
Go to Step 11 Go to Step 8

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ISUZU KB P190 2007

ENGINE CONTROL SYSTEM (4JK1/4JJ1) 6E-139
DTC P0231 or P0232 (Flash Code 69)
Circuit Description
The ECM controls the fuel pump relay which supplies
power to the fuel pump in the fuel tank. The ECM
commands the fuel pump relay ON for a certain length
of time at ignition switch is ON with the engine OFF.
During the engine running it is continuously
commanded ON. If the ECM detects an improper
voltage level on the relay control circuit, DTC P0231 or
P0232 will set.
Condition for Running the DTC • The battery voltage is more than 9 volts.
• The ignition switch is ON.
Condition for Setting the DTC • The ECM detects a low voltage condition on the fuel pump relay control circuit for longer than 3
second when the relay is commanded OFF. (DTC
P0231)
• The ECM detects a high voltage condition on the fuel pump relay control circuit for longer than 3
second when the relay is commanded ON. (DTC
P0232)
Action Taken When the DTC Sets • The ECM illuminates the SVS lamp when the diagnostic runs and fails. Refer to DTC Type
Definitions for Action Taken When the DTC Sets -
Type C. (Euro 4 Specification) • The ECM illuminates the MIL when the diagnostic
runs and fails. Refer to DTC Type Definitions for
Action Taken When the DTC Sets - Type A.
(Except Euro 4 Specification)
• The ECM limits fuel injection quantity.
• The ECM inhibits cruise control.
Condition for Clearing the DTC • Refer to DTC Type Definitions for Condition for Clearing the SVS Lamp/ DTC - Type C. (Euro 4
Specification)
• Refer to DTC Type Definitions for Condition for Clearing the MIL/ DTC - Type A. (Except Euro 4
Specification)
Diagnostic Aids • If an intermittent condition is suspected, refer to Intermittent Conditions in this section.
Notice: • The fuel pump relay is commanded ON for 12 seconds at ignition switch is ON with the engine
OFF.
Schematic Reference: Engine Controls Schematics
Connector End View Reference: Engine Controls
Connector End Views or ECM Connector End Views
Circuit/ System Testing DTC P0231
Step Action Value(s)Yes No
1 Did you perform the Diagnostic System Check -
Engine Controls? —
Go to Step 2 Go to Diagnostic
System Check -
Engine Controls
2 1. Install a scan tool.
2. Turn OFF the ignition for 30 seconds.
3. Turn ON the ignition for 20 seconds while observing the DTC Information with a scan
tool.
Does the DTC fail this ignition? —
Go to Step 3 Go to Diagnostic
Aids
3 1. Turn OFF the ignition.
2. Replace the fuel pump relay with the head light relay or replace with a known good relay.
3. Turn ON the ignition for 20 seconds while observing the DTC Information with a scan
tool.
Does the DTC fail this ignition? —
Go to Step 4 Go to Step 7

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ISUZU KB P190 2007

6E-140 ENGINE CONTROL SYSTEM (4JK1/4JJ1)
41. Turn OFF the ignition.
2. Remove the fuel pump relay.
3. Probe the ignition voltage feed circuit of the relay coil side (pin 3 of X-13) with a test lamp
that is connected a known good ground.
4. Turn ON the ignition, with the engine OFF.
Does the test lamp illuminate? —
Go to Step 5 Go to Step 6
5 1. Test the control circuit between the ECM (pin
54 of C-58) and the relay (pin 5 of X-13) for
the following conditions:
• An open circuit
• A short to ground
• High resistance
2. Repair the circuit(s) as necessary.
Did you find and correct the condition? —
Go to Step 11 Go to Step 8
6 Repair the open circuit or high resistance between
the ECM main relay (pin 1 of X-12) and the fuel
pump relay (pin 3 of X-13).
Did you complete the repair? —
Go to Step 11
—
71. Remove the fuel pump relay.
2. Inspect for an intermittent and for a poor connection on each relay terminal.
3. Repair the connection(s) as necessary.
Did you find and correct the condition? —
Go to Step 11 Go to Step 9
8 1. Turn OFF the ignition.
2. Disconnect the ECM harness connector.
3. Inspect for an intermittent and for a poor connection at the harness connector of the
ECM (pin 54 of C-58).
4. Repair the connection(s) as necessary.
Did you find and correct the condition? —
Go to Step 11 Go to Step 10
9 Replace the fuel pump relay.
Did you complete the replacement? —
Go to Step 11
—
10Important:
Replacement ECM must be
programmed and learned.
Replace the ECM. Refer to ECM Replacement.
Did you complete the replacement? —
Go to Step 11
—
111. Reconnect all previously disconnected fuse,
relay or harness connector(s).
2. Clear the DTCs with a scan tool.
3. Turn OFF the ignition for 30 seconds.
4. Turn ON the ignition for 20 seconds while observing the DTC Information with a scan
tool.
Did the DTC fail this ignition? —
Go to Step 3 Go to Step 12
12 Observe the DTC Information with a scan tool.
Are there any DTCs that you have not diagnosed? —
Go to DTC List System OK
Step
Action Value(s)Yes No

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ISUZU KB P190 2007