Isuzu KB P190. Manual - part 851

Engine Management – V6 – Diagnostics 

Page 6C1-2–126 

 

• 

DTC P0461 – Fuel Level Sensor Range / Performance 

• 

DTC P0462 – Fuel Level Sensor Low Voltage 

• 

DTC P0463 – Fuel Level Sensor High Voltage 

Circuit Description 

The fuel level sensor changes resistance based on the fuel level in the fuel tank. The engine control module (ECM) 
monitors changes in the resistance of the sensor to determine the fuel level. This information is then sent to the 
instrument cluster via the GM LAN serial data circuit. 

When the fuel tank is full, the sensor resistance is high and the ECM senses high signal voltage. When the fuel tank is 
empty, the sensor resistance is low and the ECM senses a low signal voltage. 

When the ECM senses a signal voltage outside the normal operating range of the sensor, a fuel level sensor DTC will 
set. 

Conditions for Running the DTC 

The ignition is on. 

Conditions for Setting the DTC 

DTC P0461 

The ECM detects that greater than 170 km have been accumulated and the fuel level in the fuel tank has not changed 
by at least 3.0 litres. 

DTC P0462 

The ECM detects the fuel level signal voltage is less than 0.5 V for 20 seconds. 

DTC P0463 

The ECM detects the fuel level signal voltage is greater than 4.5 V for 20 seconds. 

Conditions for Clearing the DTC 

The fuel level sensor circuit DTCs are Type C DTCs. Refer to 1.4  Diagnostic Trouble Codes in this Section, for action 
taken when Type C DTCs set and conditions for clearing Type C DTCs. 

Additional Information 

• 

Refer to 8A Electrical-Body and Chassis for further information on the fuel gauge system. 

• 

Depending on the current fuel level, it may be difficult to locate a malfunctioning sending unit. The malfunction may 
only occur when the fuel level is full or near empty. The fuel sender unit may need to be removed for further 
diagnosis. A fuel level sensor that has an intermittent condition may cause a DTC to set. Remove the fuel level 
sensor to test the resistance of the sensor, refer to 6C Fuel System – V6 for this procedure. Replace the sensor if 
the resistance is not within the specified range.  

• 

The following may occur with a fuel level sensor DTC set: 

• 

The vehicle fuel gauge displays empty.  

• 

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. 

• 

For an intermittent fault condition, refer to 5.2 

Intermittent Fault Conditions in this Section. 

• 

To assist diagnosis, refer to 3  Wiring Diagrams and Connector Charts in this Section, for the system wiring 
diagram and connector charts. 

Engine Management – V6 – Diagnostics 

Page 6C1-2–127 

 

DTC P0461, P0462 or P0463 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 or 
road test the vehicle under various driving condition. 

3 

Using Tech 2, select the DTC display function. 

Does DTC P0461, P0462, P0463 fail this ignition cycle? 

Go to Step 3 

Refer to Additional 

Information in this 

DTC 

3 

1 

Switch off the ignition. 

2 

Disconnect the fuel level sensor wiring connector.  

3 

Switch on the ignition with the engine not running. 

4 

Using a digital multimeter, measure the voltage between the fuel 
level signal circuit and the ECM housing. 

Does the multimeter indicate 4.8 – 5.2 V? 

Go to Step 4 

Go to Step 5 

4 

1 

Switch off the ignition. 

2 

Remove ECM Fuse F29 from the engine compartment fuse and 
relay panel assembly. 

3 

Using a digital multimeter, measure the resistance between the 
fuel level sensor low reference circuit and the ECM housing. 

N O T E  

Install the ECM Fuse F29 to the engine compartment fuse 
and relay panel assembly after completing this test. 

Does the multimeter indicate less than 5 

Ω? 

Go to Step 7 

Go to Step 6 

5 

Test the fuel level 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 9 

Go to Step 8 

6 

Test the fuel level sensor low 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 9 

Go to Step 8 

7 

Replace the fuel level sensor. Refer to 6C Fuel System – V6s. 

Was the repair completed? 

Go to Step 9 

– 

8 

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

Was the repair completed? 

Go to Step 9 

– 

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. 

Do any fuel level sensor DTCs fail this ignition cycle? 

Go to Step 2 

Go to Step 10 

Engine Management – V6 – Diagnostics 

Page 6C1-2–128 

 

Step Action 

Yes 

No 

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. 

7.26  DTC P0480, P0691 or P0692 

DTC Descriptors 

This diagnostic procedure supports the following DTCs: 

• 

DTC P0480 – Cooling Fan Relay 1 Circuit Malfunction 

• 

DTC P0691 – Cooling Fan Relay 1 Circuit Low Voltage 

• 

DTC P0692 – Cooling Fan Relay 1 Circuit High Voltage 

Circuit Description 

The engine control relay applies ignition positive battery voltage to the ignition circuit of the engine cooling fan relay 1 
and relay 2. Using a device called a driver, the ECM performs the following tasks: 

• 

grounds the engine cooling fan relay 1 control signal circuit to operate the small engine cooling fan, or 

• 

grounds the engine cooling fan relay 2 control signal circuit to operate both the small engine cooling fan and the 
large engine cooling fan. 

The driver has a feedback circuit that is pulled-up to a voltage. The ECM monitors the driver feedback circuit to 
determine if the control circuit is open, shorted to ground or shorted to a positive voltage. 

A cooling fan relay control circuit DTC sets if the ECM detects a fault condition in the engine cooling fan relay control 
circuit. 

Conditions for Running the DTC 

Run continuously once the following conditions are met: 

• 

the ignition voltage is 10 – 16 V, 

• 

the engine speed is greater than 40 rpm, and 

• 

the ECM driver transitions from on to off or from off to on. 

Conditions for Setting the DTC 

DTC P0480 

The ECM detects an open circuit fault condition in the control circuit of the engine cooling fan relay 1. 

DTC P0691 

The ECM detects a short to ground fault condition in the control circuit of the engine cooling fan relay 1. 

DTC P0692 

The ECM detects a short to voltage fault condition in the control circuit of the engine cooling fan relay 1. 

Conditions for Clearing DTC 

The cooling fan relay control circuit DTCs are Type B DTCs. Refer to 1.4  Diagnostic Trouble Codes in this Section, for 
action taken when Type B DTCs set and conditions for clearing Type B DTCs. 

Additional Information 

• 

Refer to 6B1 – Engine Cooling – V6 for details of the engine cooling fan operation. 

Engine Management – V6 – Diagnostics 

Page 6C1-2–129 

 

• 

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  Wiring Diagrams and Connector Charts in this Section, for the system wiring 
diagram and connector charts. 

DTC P0480, P0691 & P0692 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 or 
operate the vehicle within the conditions for setting the DTC. 

5 

Using Tech 2, select the DTC display function. 

Does DTC P0480, P0691 or P0692 fail this ignition cycle? 

Go to Step 3 

Refer to Additional 

Information in this 

DTC 

3 

1 

Remove the appropriate engine cooling fan relay. Refer to 8A 
Electrical-Body and Chassis. 

2 

Connect a test lamp between the ignition voltage circuit of the 
engine cooling fan relay and the ECM housing. 

3 

Switch on the ignition with the engine not running. 

Does the test lamp illuminate? 

Go to Step 4 

Go to Step 5 

4 

1 

Switch off the ignition. 

2 

Connect a test lamp between the control circuit of the 
appropriate engine cooling fan relay and a 12 V. 

3 

Switch on the ignition with the engine not running. 

4 

Using Tech 2, command the appropriate engine cooling fan 
relay on and then off. 

Does the test lamp turn on and off when the engine cooling fan relay 
is commanded on and off? 

Go to Step 7 

Go to Step 6 

5 

Repair the high resistance or open circuit fault condition in the ignition 
voltage circuit of the engine cooling fan relay. Refer to 8A Electrical - 
Body and Chassis for information on electrical wiring repair 
procedures. 

Was the repair completed? 

Go to Step 9 

— 

6 

Test the engine cooling fan relay control 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 9 

Go to Step 8 

7 

Replace the faulty engine cooling fan relay. Refer to 8A Electrical-
Body and Chassis. 

Was the repair completed? 

Go to Step 9 

—