2007 ISUZU KB P190 diagram

Engine Management – V6 – Diagnostics Page 6C1-2–195

Action Taken When the DTC Sets
• The control module activates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that
the diagnostic runs and fails.
• The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic
fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the
second consecutive ignition cycle, the control module records the operating conditions at the time of the failure.
The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.
Conditions for Clearing the MIL/DTC
• The control module turns OFF the malfunction indicator lamp (MIL) after four consecutive ignition cycles that the
diagnostic runs and does not fail.
• A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
• A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission
related diagnostic.
• Use Tech 2 to clear the MIL and the DTC.
Additional Information
• A fuel delivery condition causes this DTC to set. Thoroughly inspect all items that cause a rich condition.
• For an intermittent fault condition, refer to 5.2 Intermittent Fault Conditions in this Section.
• To assist diagnosis, refer to 3 W iring Diagrams and Connector Charts in this Section, for the system wiring
diagram and connector charts.
Test Description
The numbers below refer to the step numbers on the diagnostic table.
2 This step determines whether the fault is present.
4 If DTC P2188 and P2190 set at the same time, then both banks of the engine are operating rich. Inspect items that would cause both banks to operate rich.
5 Disconnecting the mass air flow (MAF) sensor determines if the MAF sensor signal is skewed. If the Short Term FT parameter changes more than the specified value, there is a condition with the MAF sensor. A MAF sensor
condition can cause this DTC without setting a MAF DTC. If there is a MAF sensor condition, the MAF sensor
parameters will appear to be within range.
DTC P2188 or P2190 Diagnostic Table
Step Action Value(s) Yes No
1
Has the Diagnostic System Check been completed? —
Go to Step 2 Refer to
4.4 Diagnostic System Check in this Section
2 NOTE
If any DTCs are set, except P2188 and
P2190, refer to those DTCs before
proceeding with this diagnostic.
1 Idle the engine at the normal operating temperature.
2 Check that the fuel system is in Closed Loop.
3 Observe the Total Fuel Trim Avg. parameter for bank 1 and / or bank 2 with Tech 2.
Is the Total Fuel Trim Avg. less than the specified
value? –40%
Go to Step 3 Go to Step 4

BACK TO CHAPTER INDEX
TO MODEL INDEX
ISUZU KB P190 2007

Engine Management – V6 – Diagnostics Page 6C1-2–198

• The rear fuel trim, long and short term, is more than a threshold.
• This DTC sets after the air flow coming into the engine accumulates to more than 200 grams and the above
conditions are met for more than 4 seconds.
Condition 2
• The ECM detects that the rear HO2S is operating too rich while the ECM is commanding a lean air / fuel mixture.
• This DTC sets after the air flow coming into the engine accumulates to more than 800 grams and the above
condition is met for more than 4 seconds.
Action Taken When the DTC Sets
• The ECM activates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the
diagnostic runs and fails.
• The ECM records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the
control module stores this information in the Failure Records. If the diagnostic reports a failure on the second
consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The
control module writes the operating conditions to the Freeze Frame and updates the Failure Records.
Conditions for Clearing the MIL/DTC
• The control module turns OFF the malfunction indicator lamp (MIL) after four consecutive ignition cycles that the
diagnostic runs and does not fail.
• A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
• A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission
related diagnostic.
• Use Tech 2 to clear the MIL and the DTC.
Additional Information
• A HO2S fault condition may cause this DTC to set. Thoroughly inspect all items that could cause a lean condition.
• For an intermittent fault condition, refer to 5.2 Intermittent Fault Conditions in this Section.
• Since a fault condition in a wiring connector may trigger DTCs, always test the connectors related to this
diagnostic procedure for shorted terminals or poor wiring connection before replacing any component. Refer to 8A
Electrical - Body and Chassis for information on electrical fault diagnosis.
• To assist diagnosis, refer to 3 W iring Diagrams and Connector Charts in this Section, for the system wiring
diagram and connector charts.
Test Description
The numbers below refer to the step numbers on the diagnostic table.
2 This step determines if a condition exists.
5 This step is testing for a rear HO2S sensor circuit condition. A circuit condition sets this DTC.
8 This step is testing for an intermittent circuit condition. Thoroughly inspect the HO2S circuits for an intermittent circuit condition.
9 This step is testing for an intermittent circuit condition. Thoroughly inspect the HO2S circuits for an intermittent circuit condition.
DTC P2195 or P2197 Diagnostic Table
Step Action Value(s) Yes No
1
Has the Diagnostic System Check been completed? —
Go to Step 2 Refer to
4.4 Diagnostic
System Check in this Section

BACK TO CHAPTER INDEX
TO MODEL INDEX
ISUZU KB P190 2007

Engine Management – V6 – Diagnostics Page 6C1-2–202

Conditions for Setting the DTC
Condition 1
• The ECM detects that the front HO2S is operating too rich while the rear HO2S is operating too lean and the ECM
detects that the fuel trim is at minimum control,
OR
• The rear fuel trim, long and short term, is less than a threshold.
• This DTC sets after the air flow coming into the engine accumulates to more than 200 grams and the above
conditions are met for more than 4 seconds.
Condition 2
• The ECM detects that the rear HO2S is operating too lean while the ECM is commanding a rich air / fuel mixture.
• This DTC sets after the air flow coming into the engine accumulates to more than 800 grams and the above
condition is met for more than 4 seconds.
Action Taken When the DTC Sets
• The ECM activates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the
diagnostic runs and fails.
• The ECM records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the
control module stores this information in the Failure Records. If the diagnostic reports a failure on the second
consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The
control module writes the operating conditions to the Freeze Frame and updates the Failure Records.
Conditions for Clearing the MIL/DTC
• The control module turns OFF the malfunction indicator lamp (MIL) after four consecutive ignition cycles that the
diagnostic runs and does not fail.
• A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
• A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission
related diagnostic.
• Use Tech 2 to clear the MIL and the DTC.
Additional Information
• A HO2S fault condition may cause this DTC to set. Thoroughly inspect all items that could cause a rich condition.
• For an intermittent fault condition, refer to 5.2 Intermittent Fault Conditions in this Section.
• Since a fault condition in a wiring connector may trigger DTCs, always test the connectors related to this
diagnostic procedure for shorted terminals or poor wiring connection before replacing any component. Refer to 8A
Electrical - Body and Chassis for information on electrical fault diagnosis.
• To assist diagnosis, refer to 3 W iring Diagrams and Connector Charts in this Section, for the system wiring
diagram and connector charts.
Test Description
The numbers below refer to the step numbers on the diagnostic table.
2 This step determines if a condition exists.
5 This step is testing for a rear HO2S sensor circuit condition. A circuit condition sets this DTC.
8 This step is testing for an intermittent circuit condition. Thoroughly inspect the HO2S circuits for an intermittent circuit condition.
9 This step is testing for an intermittent circuit condition. Thoroughly inspect the HO2S circuits for an intermittent circuit condition.

BACK TO CHAPTER INDEX
TO MODEL INDEX
ISUZU KB P190 2007

Engine Management – V6 – Diagnostics Page 6C1-2–206

• The engine is running.
Conditions for Setting the DTC
DTC P2227
The ECM detects the BARO pressure changed greater than 5 kPa within 20 seconds or the BARO pressure changed
greater than 30 kPa since the last ignition cycle.
DTC P2228
The ECM detects the BARO sensor signal voltage is less than 0.20 V.
DTC P2229
The ECM detects the BARO sensor signal voltage is greater than 4.8 V for longer than 2.0 seconds.
Conditions for Clearing DTC
The BARO pressure sensor circuit DTCs are Type ‘B’ DTC. Refer to 1.4 Diagnostic Trouble Codes in this Section, for
action taken when a Type ‘B’ DTC sets and conditions for clearing Type ‘B’ DTCs.
Additional Information
• Refer to 6C1-1 Engine Management – V6 – General Information for details of the BARO Sensor operation.
• For an intermittent fault condition, refer to 5.2 Intermittent Fault Conditions in this Section.
• Since fault condition in a wiring connector may trigger DTCs, always test the connectors related to this diagnostic
procedure for shorted terminals or poor wiring connection before replacing any component. Refer to 8A Electrical -
Body and Chassis for information on electrical fault diagnosis.
• To assist diagnosis, refer to 3 W iring Diagrams and Connector Charts in this Section, for the system wiring
diagram and connector charts.
Test Description
The following numbers refer to the step numbers in the diagnostic table:
4 Test signal circuit of the BARO sensor. This circuit should display a voltage within the specified range.
5 Measures the integrity of the TP sensor low reference circuit. Removal of the ECM Fuse 29 enables the ECM to power down completely prior to the test procedure.
DTC P2227 P2228 or P2229 Diagnostic Table
Step Action Yes No
1 Has the Diagnostic System Check been performed?
Go to Step 2 Refer to
4.4 Diagnostic
System Check in this Section
2 1 Switch off the ignition for 30 seconds.
2 Operate the vehicle within the conditions for running the DTC.
3 Using Tech 2, select the DTC display function.
Does DTC P2227, P2228 or P2229 fail this ignition cycle? Go to Step 3 Refer to Additional
Information in this DTC

BACK TO CHAPTER INDEX
TO MODEL INDEX
ISUZU KB P190 2007

Engine Management – V6 – Diagnostics Page 6C1-2–207

Step Action Yes
No
3 1 Switch off the ignition.
2 Disconnect the BARO sensor wiring connector.
3 Switch on the ignition with the engine not running.
4 Using a digital multimeter, measure the voltage between the BARO sensor signal circuit and the ECM housing.
Does the multimeter display 4.5 – 5.5 V? Go to Step 4 Go to Step 6
4 1 Switch on the ignition with the engine not running.
2 Using a digital multimeter, measure the voltage between the BARO sensor 5 V reference circuit and the ECM housing.
Does the multimeter display 4.8 – 5.2 V? Go to Step 5 Go to Step 7
5 1 Switch off the ignition.
2 Remove ECM / TCM Fuse 29 from the engine compartment fuse and relay panel assembly.
3 Using a digital multimeter, measure the resistance between the BARO sensor low reference circuit and the ECM housing.
NOTE
Install the ECM Fuse 29 to the engine compartment fuse
and relay panel assembly after completing this test.
Does the multimeter display 5 Ω? Go to Step 9 Go to Step 8
6 Test BARO sensor signal circuit for a high resistance, open circuit,
short to ground or short to voltage fault condition. Refer to 8A
Electrical - Body and Chassis for information on electrical fault
diagnosis.
W as any fault found and rectified? Go to Step 11 Go to Step 10
7 Test the BARO sensor 5 V reference circuit for an open, short to
ground or high resistance fault condition. Refer to 8A Electrical - Body
and Chassis for information on electrical fault diagnosis.
NOTE
The BARO sensor shares the 5 V reference circuit with
other sensors. A fault condition in the 5 V reference circuit
may trigger DTCs on sensors that share this circuit. Refer
to 3 W iring Diagrams and Connector Charts in this
Section, to assist diagnosis.
W as any fault found and rectified? Go to Step 11 Go to Step 10
8 1 Disconnect the ECM wiring connector.
2 Test the BARO sensor low reference circuit for a high resistance and open circuit fault condition. Refer to 8A Electrical - Body
and Chassis for information on electrical fault diagnosis.
W as any fault found and rectified? Go to Step 11 Go to Step 10
9 Replace the BARO sensor. Refer to 6C1-3 Engine Management – V6
– Service Operations.
W as the repair completed? Go to Step 11 —
10 Replace the ECM. Refer to 6C1-3 Engine Management – V6 –
Service Operations.
W as the repair completed? Go to Step 11 —

BACK TO CHAPTER INDEX
TO MODEL INDEX
ISUZU KB P190 2007

Engine Management – V6 – Diagnostics Page 6C1-2–210

• The internal HO2S signal voltage switches at the same rate as the heater circuit.
• The above condition occurs 4 times out of 6 as the heater is turned off.
DTC P2251 or P2254
The ECM detects the following conditions:
• The internal HO2S signal voltage changes greater than 10 mV as the heater control switches.
• The above condition occurs 20 times in the last 10 seconds.
Conditions for Clearing the DTC
The HO2S signal circuit shorted to heater control circuit DTCs are Type ‘B’ DTCs. Refer to 1.4 Diagnostic Trouble
Codes in this Section, for action taken when Type ‘B’ DTC sets and conditions for clearing Type ‘B’ DTCs.
Additional Information
• Refer to 6C1-1 Engine Management – V6 – General Information for details of the HO2S system operation.
• For an intermittent fault condition, refer to 5.2 Intermittent Fault Conditions in this Section.
• The HO2S must be tightened correctly. A loose HO2S will trigger these DTCs.
• Since fault condition in a wiring connector may trigger DTCs, always test the connectors related to this diagnostic
procedure for shorted terminals or poor wiring connection before replacing any component. Refer to 8A Electrical -
Body and Chassis for information on electrical fault diagnosis.
• To assist diagnosis, refer to 3 W iring Diagrams and Connector Charts in this Section, for the system wiring
diagram and connector charts.
DTC P2231, P2232, P2234, P2235, P2251or P2254 Diagnostic Table
Step Action Yes No
1 Has the Diagnostic System Check been performed?
Go to Step 2 Refer to
4.4 Diagnostic
System Check in this Section
2 1 Switch off the ignition for 30 seconds.
2 Start the engine.
3 Allow the engine to reach the normal operating temperature.
4 Increase the engine speed to 2,000 rpm for 10 seconds.
5 Using Tech 2, select the DTC display function.
Does DTC P2231, P2232, P2234, P2235, P2251 or P2254 fail this
ignition cycle? Go to Step 3 Refer to Additional
Information in this DTC
3 1 Disconnect the appropriate HO2S connector.
2 From the HO2S to the sensor wiring connector, test the following circuit for a shorted to the sensor heater control circuit
fault condition:
• Reference signal circuit,
• low reference circuit,
• pump current,
• input pump current.
Refer to 8A Electrical - Body and Chassis for information on electrical fault diagnosis.
W as any fault found? Go to Step 6 Go to Step 4

BACK TO CHAPTER INDEX
TO MODEL INDEX
ISUZU KB P190 2007

Engine Management – V6 – Diagnostics Page 6C1-2–213

Conditions for Clearing the DTC
The HO2S pumping current control circuit DTCs are Type ‘B’ DTCs. Refer to 1.4 Diagnostic Trouble Codes in this
Section for action taken when Type ‘B’ DTC sets and conditions for clearing Type ‘B’ DTCs.
Additional Information
• Refer to 6C1-1 Engine Management – V6 – General Information for details of the HO2S system operation.
• For an intermittent fault condition, refer to 5.2 Intermittent Fault Conditions in this Section.
• Inspect the HO2S wiring harness for contact with the exhaust system.
• The HO2S must be tightened correctly. A loose HO2S will trigger these DTCs.
• Since fault condition in a wiring connector may trigger DTCs, always test the connectors related to this diagnostic
procedure for shorted terminals or poor wiring connection before replacing any component. Refer to 8A Electrical-
Body and Chassis for information on electrical fault diagnosis.
• To assist diagnosis, refer to 3 W iring Diagrams and Connector Charts in this Section for the system wiring
diagram and connector charts.
• The following table illustrates the typical voltages for the HO2S circuits:
HO2S Voltages
Conditions: • Ignition ON, Engine OFF
• HO2S Disconnected
HO2S Circuit Voltage
Heater Control 4.6 – 5.0 V
Heater Supply Voltage B+
Reference Voltage 2.6 – 3.1 V
Low Reference 2.2 – 2.7 V
Pump Current Less than 0.5 A
Input Pump Current Less than 0.5 A
Test Description
The following numbers refer to the step numbers in the diagnostic table:
2 W hen performing this test, the HO2S should react immediately.
4 Connecting a jumper wire between the HO2S reference signal circuit and the low reference circuit causes the ECM to apply signal voltage to the pumping current and input pumping current.
DTC P2237, P2238, P2239, P2240 or P2242 Diagnostic Table
Step Action Value(s) Yes No
1
Has the Diagnostic System Check been completed? —
Go to Step 2 Refer to
4.4 Diagnostic System Check
2 1 Switch off the ignition for 30 seconds.
2 Start the engine.
3 Allow the engine to reach the normal operating temperature.
4 Increase the engine speed to 2,000 rpm for 10 seconds.
5 Using Tech 2, select the DTC display function.
Does DTC P2237, P2238, P2239, P2240, P2241,
P2242, fail this ignition cycle? —
Go to Step 3 Refer to Additional
Information in this DTC

BACK TO CHAPTER INDEX
TO MODEL INDEX
ISUZU KB P190 2007

Engine Management – V6 – Diagnostics Page 6C1-2–216

• The ignition voltage is between 10.7 – 18.0 volts.
• The fuel system is in fuel shut-off mode.
• The calculated exhaust temperature is less than 750°C.
• The heated oxygen sensors are at operating temperature.
• DTC P2626 and P2629 runs continuously once the above conditions are met.
Conditions for Setting the DTC
• The ECM internal HO2S voltage is more than 4.81 volts.
• The condition exists for more than 4 seconds or 600 seconds if the fuel level is less than 12 percent.
Action Taken When the DTC Sets
• The ECM illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the
diagnostic runs and fails.
• The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic
fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the
second consecutive ignition cycle, the control module records the operating conditions at the time of the failure.
The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.
Conditions for Clearing the DTC
• The ECM turns OFF the malfunction indicator lamp (MIL) after four consecutive ignition cycles that the diagnostic
runs and does not fail.
• A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
• A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission
related diagnostic.
• Use Tech 2 to clear the MIL and the DTC.
Additional Information
• Use the J 35616 Connector Test Adapter Kit for any test that requires probing the ECM harness connector or a
component harness connector.
• The lower connector of the ECM is connector A43-X1 and the upper connector of the ECM is connector A43-X2.
Refer to 3 W iring Diagrams and Connector Charts.
• The front wide band sensors do not toggle or switch like a switching HO2S. The front HO2S signals will be
relatively stable for an idling engine.
• For an intermittent fault condition, refer to 5.2 Intermittent Fault Conditions in this Section.
• Since fault condition in a wiring connector may trigger DTCs, always test the connectors related to this diagnostic
procedure for shorted terminals or poor wiring connection before replacing any component. Refer to 8A Electrical-
Body and Chassis for information on electrical fault diagnosis.
• To assist diagnosis, refer to 3 W iring Diagrams and Connector Charts in this Section for the system wiring
diagram and connector charts.
• The following table illustrates the typical voltages for the HO2S circuits:
HO2S Voltages
Conditions: • Ignition ON, Engine OFF
• HO2S Disconnected
HO2S Circuit Voltage
Heater Control 4.6 – 5.0 V
Heater Supply Voltage B+
Reference Voltage 2.6 – 3.1 V

BACK TO CHAPTER INDEX
TO MODEL INDEX
ISUZU KB P190 2007