Isuzu KB P190. Manual - part 856

Engine Management – V6 – Diagnostics 

Page 6C1-2–146 

 

Step Action 

Yes 

No 

3 

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 P0532 or P0533 fail this ignition cycle? 

Go to Step 4 

Refer to Additional 

Information in this 

DTC 

4 

1 

Switch off the ignition. 

2 

Disconnect the A/C pressure sensor connector. 

3 

Switch on the ignition with the engine not running. 

4 

Using a digital multimeter, measure the voltage between the 
A/C pressure 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 

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

2 

Switch on the ignition with the engine not running. 

3 

Using Tech 2, observe the ECM A/C pressure voltage 
parameter. 

Does Tech 2 display 4.8 – 5.2 V? 

Go to Step 6 

Go to Step 8 

6 

1 

Switch off the ignition. 

2 

Remove ECM Fuse 29 from the engine compartment fuse and 
relay panel assembly. 

3 

Using a digital multimeter, measure the resistance between the 
A/C refrigerant pressure 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 the test. 

Does the multimeter display 5

Ω?  

Go to Step 10 

Go to Step 9 

7 

Test the A/C pressure sensor 5 V reference 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. 

Was any fault found and rectified? 

Go to Step 12 

Go to Step 11 

8 

Test the A/C pressure 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. 

Was any fault found and rectified? 

Go to Step 12 

Go to Step 11 

9 

Test the A/C pressure sensor low reference circuit for a high 
resistance or open circuit condition. Refer to 8A Electrical - Body and 
Chassis for information on electrical fault diagnosis. 

Was any fault found and rectified? 

Go to Step 12 

Go to Step 11 

10  Replace the A/C pressure sensor. Refer to 6C1-3 Engine 

Management – V6 – Service Operations. 

Was the repair completed? 

Go to Step 12 

— 

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

Service Operations. 

Was the repair completed? 

Go to Step 12 

— 

Engine Management – V6 – Diagnostics 

Page 6C1-2–147 

 

Step Action 

Yes 

No 

12  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 A/C refrigerant pressure sensor circuit DTCs fail this 
ignition cycle? 

Go to Step 2 

Go to Step 13 

13  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. 

7.33  DTC P0560, P0562 or P0563 

DTC Descriptors 

This diagnostic procedure supports the following DTCs: 

• 

DTC P0560 – System Voltage Malfunction 

• 

DTC P0562 – System Voltage Low Voltage 

• 

DTC P0563 – System Voltage High Voltage 

Circuit Description 

Battery voltage is supplied continuously to the engine control module (ECM) through the continuous battery supply 
circuit and the ground through the ground connection of the ECM housing to the engine. 

Turning the ignition switch on activates the ignition control relay, which directs ignition positive voltage from the battery 
to the ECM switched battery supply circuit which activates the ECM. The ECM then applies control voltage to the control 
circuit of the engine control relay to activate the engine control relay. The engine control relay supplies ignition voltage 
to the various engine management system components. 

The ECM monitors the battery voltage circuits to ensure the voltage available to the engine management system stays 
within the specified range. Incorrect system voltage may cause incorrect engine management system operation or 
component malfunction. 

An ECM system voltage DTC sets if the ECM detects the voltage available to any of the ECM voltage supply circuit is 
outside the specified range. 

Conditions for Running the DTC 

DTCs P0560, P0563 and P0563 runs continuously when the engine is running at speeds greater than 1500 rpm 

Conditions for Setting the DTC 

DTC P0560 

The ECM detects the ignition 1, ignition 2 or switched battery supply voltage is out of the specified range for 30 seconds. 

DTC P0562 

The ECM detects the ECM system voltage is less than 11 V for 5 seconds. 

DTC P0563 

The ECM detects the ECM system voltage is greater than 16 V. 

Engine Management – V6 – Diagnostics 

Page 6C1-2–148 

 

Conditions for Clearing the DTC 

The ECM system voltage DTCs are Type C DTCs. Refer to 1.4 Diagnostic Trouble Codes in this Section, for action 
taken when a Type C DTC sets and conditions for clearing Type C DTCs. 

Additional Information 

• 

For an intermittent fault condition, refer to 5.2 

Intermittent Fault Conditions in this Section. 

• 

Refer to 6C1-1 Engine Management – V6 – General Information for details of the ECM operation. 

• 

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. 

DTC P0560, P0562 or P0563 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 

Increase the engine speed to 1500 rpm or operate the vehicle 
within the conditions for running the DTC. 

3 

Using Tech 2, select the DTC display function. 

Does DTC P0560, P0562, or P0563 fail this ignition cycle? 

Go to Step 3 

Refer to Additional 

Information in this 

DTC 

3 

Test the battery condition. Refer to 6D1-3 Battery – V6. 

Was any fault found and rectified? 

Go to Step 9 

Go to Step 4 

4 

Test the charging system operation. Refer to 6D1-1 Charging System 
– V6. 

Was any fault found and rectified? 

Go to Step 9 

Go to Step 5 

5 

Test all the ECM fuses. Refer to 8A Electrical - Body and Chassis. 

Was any fault found and rectified? 

Go to Step 9 

Go to Step 6 

6 

Check the ECM ground connections for corrosion, loose terminal or 
incorrect position. Refer to 8A Electrical - Body and Chassis for 
information on electrical fault diagnosis. 

Was any fault found and rectified? 

Go to Step 9 

Go to Step 7 

7 

Test the following circuits for a high resistance or open circuit fault 
condition.  

• 

Continuous battery supply circuit, 

• 

switched battery supply circuit, 

• 

ignition 1 circuit, and 

• 

ignition 2 circuit. 

Refer to 8A Electrical - Body and Chassis for information on electrical 
fault diagnosis. 

Was any fault found and rectified? 

Go to Step 9 

Go to Step 8 

8 

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

Was the repair completed? 

Go to Step 9 

— 

Engine Management – V6 – Diagnostics 

Page 6C1-2–149 

 

Step Action 

Yes 

No 

9 

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 ECM system voltage DTCs fail this ignition cycle? 

Go to Step 2 

Go to Step 10 

10  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. 

7.34  DTC P0601, P0602, P0604 or P0606 

DTC Description 

This diagnostic procedure supports the following DTCs: 

• 

DTC P0601 – Replace Electronic Control Unit (ECU) 

• 

DTC P0602 – Program Electronic Control Unit (ECU) 

• 

DTC P0604 – Replace Electronic Control Unit (ECU) 

• 

DTC P0606 – Replace Electronic Control Unit (ECU) 

Circuit Description 

The engine control module (ECM) is the control centre of the engine management system. The programming and 
calibration needed by the ECM to control the functionality of the engine management system are stored in the ECM read 
only memory (ROM). 

An ECM internal circuit, programming or memory fault DTC sets if there is an internal microprocessor integrity fault 
condition with the ECM or if the ECM is not programmed. 

Conditions for Running the DTC 

DTC P0601 

Runs once when the checksum calculation at power down is completed in the last ignition cycle. 

DTC P0602 and P0606 

Runs continuously when the ignition is switched on with the engine not running. 

DTC P0604 

Runs once when the read / write test at power-down is completed in the last ignition cycle. 

Conditions for Setting the DTC 

DTC P0601 

The ECM detects an incorrect ROM checksum for greater than 30 seconds. 

DTC P0602 

The ECM programming is incomplete. 

DTC P0604 

The ECM detects an error in the RAM for 6 seconds.