Isuzu KB P190. Manual — part 855

Engine Management – V6 – Diagnostics

Page 6C1-2–142

Step Action

Yes

No

8

Using Tech 2, select the DTC display function.

Does Tech 2 display any DTCs?

Go to the

appropriate DTC

Table in this Section

System OK

When all diagnosis and repairs are completed, clear all DTCs and check the system for correct operation.

7.31 DTC P0521, P0522 or P0523

DTC Descriptors

This diagnostic procedure supports the following DTCs:

•

DTC P0521 – Oil Pressure Sensor Range / Performance

•

DTC P0522 – Oil Pressure Sensor Voltage Low

•

DTC P0523 – Oil Pressure Sensor Voltage High

Circuit Description

The ECM applies a positive 5 V reference voltage to the engine oil pressure (EOP) sensor through the 5 V reference
circuit and the ground through the low reference circuit.

The EOP sensor provides signal voltage to the ECM that is proportional to the oil pressure generated by the engine oil
pump. The ECM monitors the EOP sensor signal voltage. If the ECM detects a low oil pressure condition, it sends a
serial data communication signal to the instrument cluster to illuminate the check oil warning icon.

The ECM monitors and compares the EOP sensor signal voltage against a specified range. An EOP sensor circuit DTC
sets if the ECM detects the EOP sensor signal voltage is outside the specified range.

Conditions for Running the DTC

DTC P0521, P0522 and P0523 run continuously when the engine is running.

Conditions for Setting the DTC

P0521

The ECM detects engine oil pressure is:

•

greater than 800 kPa at idle, or

•

engine rpm is greater than 2000 rpm and oil pressure is less than 8 kPa.

P0522

The oil pressure sensor signal voltage is less than 0.2 V for more than 10 seconds.

P0523

The oil pressure sensor signal voltage is more than 4.9 V for more than 10 seconds.

Conditions for Clearing DTC

The EOP 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 EOP 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.

Engine Management – V6 – Diagnostics

Page 6C1-2–143

•

To assist diagnosis, refer to 3 Wiring 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 EOP sensor. This circuit should display a voltage within the specified range.

5

Measures the integrity of the EOP sensor low reference circuit. Removal of the ECM Fuse 29 enables the ECM to
power down completely prior to the test procedure.

P0521 to P0523 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 P0521, P0522 or P0523 fail this ignition cycle?

Go to Step 3

Refer to Additional

Information in this

DTC

3

1

Switch off the ignition.

2

Disconnect the EOP sensor wiring connector.

3

Switch on the ignition with the engine not running.

4

Using a digital multimeter, measure the voltage between the
EOP sensor 5 V reference circuit and the ECM housing.

Does the multimeter display 4.8 – 5.2 V?

Go to Step 4

Go to Step 6

4

1

Connect a 3 A fused jumper wire between the EOP sensor 5 V
reference circuit and the EOP sensor signal circuit.

2

Switch on the ignition with the engine not running.

3

Using Tech 2, observe the EOP sensor parameter.

Does Tech 2 display 780 – 980 kPa?

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
EOP sensor low reference circuit and the ECM housing.

N O T E

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 the EOP 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.

Was any fault found and rectified?

Go to Step 11

Go to Step 10

7

Test EOP sensor signal circuit for short to ground fault condition.
Refer to 8A Electrical - Body and Chassis for information on electrical
fault diagnosis.

Was any fault found and rectified?

Go to Step 11

Go to Step 10

Engine Management – V6 – Diagnostics

Page 6C1-2–144

Step Action

Yes No

8

1

Disconnect the ECM wiring connector.

2

Test the EOP 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.

N O T E

The EOP sensor shares the low reference circuit with
other sensors. A fault condition in the low reference circuit
may trigger DTCs on sensors that share this circuit. Refer
to

3 Wiring Diagrams and Connector Charts in this

Section, to assist diagnosis.

Was any fault found and rectified?

Go to Step 11

Go to Step 10

9

Replace the EOP sensor. Refer to 6C1-3 Engine Management – V6 –
Service Operations.

Was the repair completed?

Go to Step 11

—

10 Replace the ECM. Refer to 6C1-3 Engine Management – V6 –

Service Operations.

Was the repair completed?

Go to Step 11

—

11 1

Using Tech 2, clear the DTCs.

2

Switch off the ignition for 30 seconds.

3

Start the engine.

4

Operate the vehicle within the conditions for running the DTC.

Does any of the for the engine oil pressure sensor circuit DTCs s fail
this ignition cycle?

Go to Step 2

Go to Step 12

12 Using Tech 2, select the DTC display function.

Does Tech 2 display any DTCs?

Go to the

appropriate DTC

Table in this Section

System OK

When all diagnosis and repairs are completed, check the system for correct operation.

7.32 DTC P0532 or P0533

DTC Descriptors

This diagnostic procedure supports the following DTCs:

•

DTC P0532 – A/C Pressure Sensor Voltage Low

•

DTC P0533 – A/C Pressure Sensor Voltage High

Circuit Description

The ECM supplies a positive 5 V reference voltage to the air-conditioning (A/C) refrigerant pressure sensor through
reference circuit and the ground through the low reference circuit.

The A/C pressure sensor provides signal voltage to the ECM through the signal circuit that is proportional to the A/C
refrigerant pressure. The ECM monitors the signal voltage of the A/C pressure sensor to determine the refrigerant
pressure.

•

The A/C pressure sensor voltage increases as the refrigerant pressure increases.

•

When the ECM detects the refrigerant pressure exceeds a predetermined value, the ECM activates the cooling
fans to reduce the refrigerant pressure.

•

When the ECM detects the refrigerant pressure is too high or too low, the ECM disables the A/C clutch to protect
the A/C compressor from damage.

Engine Management – V6 – Diagnostics

Page 6C1-2–145

An A/C refrigerant pressure sensor circuit DTC sets if the ECM detects the A/C pressure sensor signal is not within the
specified range for 3 seconds.

Conditions for Running the DTC

DTC P0532 and P0533 run continuously when the engine is running or when the A/C is switched on.

Conditions for Setting the DTC

DTC P0532

The A/C refrigerant pressure signal voltage is less than 0.2 V for longer than 3 seconds.

DTC P0533

The A/C refrigerant pressure signal voltage is greater than 4.9 V for longer than 3 seconds.

Conditions for Clearing the DTC

The A/C refrigerant pressure sensor circuit DTCs are Type C DTCs. Refer to 1.4

Diagnostic Trouble Codes in this

Section, for action taken when Type C DTC sets and conditions for clearing Type C DTCs.

Additional Information

•

Refer to 6C1-1 Engine Management – V6 – General Information for details of the A/C Refrigerant Pressure Sensor
operation.

•

For an intermittent fault condition, refer to 5.2

Intermittent Fault Conditions in this Section.

•

The A/C refrigerant pressure sensor circuit diagnostic table is developed with the assumption the A/C refrigerant
system is functioning correctly. Therefore, rectify any A/C refrigerant system fault conditions before proceeding
with this diagnostic procedure.

−

An A/C refrigerant low-pressure fault condition may cause DTC P0532 to set.

−

An A/C refrigerant high-pressure fault condition may cause DTC P0533 to set.

•

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 Wiring 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:

2

Determines if there is an A/C refrigerant system fault condition.

6

Measures the integrity of the A/C Refrigerant Pressure Sensor low reference circuit. Removal of the ECM Fuse 29
enables the ECM to power down completely prior to the test procedure.

DTC P0532 or P0533 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

Test the A/C refrigerant system. Refer to 2A Heater and Air-
conditioning.

Was any fault found and rectified?

Go to Step 12

Go to Step 3