Isuzu KB P190. Manual - part 482

ENGINE CONTROL SYSTEM (4JK1/4JJ1)   6E-311

In-Tank Fuel Pump System Check

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 is running it is continuity commanded
ON.

In-tank Fuel Pump Control Operation

• The battery voltage is more than 9 volts.

• The ignition switch is ON.

• The fuel pump is commanded ON for 12 seconds

at ignition switch is ON with the engine OFF.

• The fuel pump is continuously ON while engine is

running.

Schematic Reference: Engine Controls Schematics

Connector End View Reference: Engine Controls
Connector End Views or ECM Connector End Views

Circuit/ System Testing In-Tank Fuel Pump System Check

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, then start
the engine.

4.

Monitor the DTC Information with a scan tool.

Is DTC P0231 or P0232 set?

—

Refer to Applicable 

DTC

Go to Step 3

3

1.

Turn OFF the ignition for 30 seconds.

2.

Remove the fuel filler cap.

3.

Turn ON the ignition, with the engine OFF.

Is the fuel pump operating sound heard from the
fuel filler?

—

Go to Step 4

Go to Step 7

4

Does the fuel pump operating sound stop after
approximately 12 seconds passed?

—

Go to Step 21

Go to Step 5

5

1.

Turn OFF the ignition for 30 seconds.

2.

Replace the fuel pump relay with the head
light relay or replace with a known good relay.

3.

Turn ON the ignition, with the engine OFF.

Does the fuel pump operating sound stop after
approximately 12 seconds passed?

—

Go to Step 20

Go to Step 6

6

Repair the short to battery or ignition voltage
between the fuel pump relay (pin 2 of X-13) and the
fuel pump (pin 1 of F-2).

Did you complete the repair?

—

Go to Step 25

—

7

1.

Turn OFF the ignition for 30 seconds.

2.

Replace the fuel pump relay with the head
light relay or replace with a known good relay.

3.

Turn ON the ignition, with the engine OFF.

Is the fuel pump operating sound heard from the
fuel filler?

—

Go to Step 17

Go to Step 8

8

Inspect the Fuel Pump (10A) fuse in the engine
room fuse block.

Is the Fuel Pump (10A) fuse open?

—

Go to Step 9

Go to Step 10

6E-312   ENGINE CONTROL SYSTEM (4JK1/4JJ1)

9

Replace the Fuel Pump (10A) fuse. If the fuse
continues to open, repair the short to ground on a
circuit fed by the fuse or check for a shorted
attached component.

Did you complete the repair?

—

Go to Step 25

—

10

1.

Turn OFF the ignition.

2.

Remove the fuel pump relay.

3.

Probe the battery voltage feed circuit of the
relay (pin 1 of X-13) with a test lamp that is
connected to a known good ground.

Does the test lamp illuminate?

—

Go to Step 12

Go to Step 11

11

Repair the open circuit or high resistance between
the Fuel Pump (10A) fuse and the fuel pump relay
(pin 1 of X-13).

Did you complete the repair?

—

Go to Step 25

—

12

1.

Reconnect the fuel pump relay.

2.

Disconnect the fuel pump resistor harness
connector.

3.

Measure the resistance across the fuel pump
resistor.

Is the resistance within the specified value?

2.2 to 2.7 

Ω

Go to Step 13

Go to Step 23

13

1.

Connect a test lamp between the fuel pump
side voltage feed circuit on the resistor
harness (pin 1 of C-157) and a known good
ground.

2.

Turn ON the ignition, with the engine OFF.

Does the test lamp illuminate for approximately 12
seconds then go out?

—

Go to Step 14

Go to Step 15

14

Connect a test lamp between the ground circuit on
the resistor harness (pin 2 of C-157) and battery
voltage.

Does the test lamp illuminate?

—

Go to Step 18

Go to Step 16

15

1.

Test the fuel pump circuit between the fuel
pump (pins 1 and 4 of F-2) and the fuel pump
relay (pin 2 of X-13) or the fuel pump resistor
(pin 1 of C-157) for an open circuit or high
resistance.

2.

Repair the circuit(s) as necessary.

Did you find and correct the condition?

—

Go to Step 25

Go to Step 19

16

Repair the open circuit or high resistance between
the fuel pump resistor (pin 2 of C-57) and the body
ground terminal (C-109). Clean or tighten ground
as necessary.

Did you complete the repair?

—

Go to Step 25

—

17

1.

Remove the fuel pump relay.

2.

Inspect for an intermittent and for poor
connection on each relay terminal.

3.

Repair the connection(s) as necessary.

Did you find and correct the condition?

—

Go to Step 25

Go to Step 20

Step

Action

Value(s)

Yes

No

ENGINE CONTROL SYSTEM (4JK1/4JJ1)   6E-313

18

1.

Inspect for an intermittent, poor connections
and corrosion at the harness connector of the
fuel pump resistor (pins 1 and 2 of C-57).

2.

Repair the connection(s) as necessary.

Did you find and correct the condition?

—

Go to Step 25

—

19

1.

Inspect for an intermittent, for poor
connections and corrosion at the harness
connector of the fuel pump (pins 1 and 4 of F-
2).

2.

Repair the connection(s) as necessary.

Did you find and correct the condition?

—

Go to Step 25

Go to Step 24

20

Replace the fuel pump relay.

Did you complete the replacement?

—

Go to Step 25

—

21

1.

Make sure the fuel amount in the fuel tank.
Refill adequate fuel as necessary.

2.

Check the fuel system connections between
the fuel tank and the fuel supply pump for
tightness and all fuel hoses for cuts, kinks,
cracks and for the use of proper clamps.
Repair or replace as necessary.

3.

Turn OFF the ignition.

4.

Disconnect the fuel hose that connects to the
fuel filter inlet side. In order to measure the
discharged fuel amount, put the hose into a
bottle or a container with a scale. (The inlet of
a bottle or a container must be larger than the
diameter of hose.)

5.

Turn ON the ignition for 20 seconds, with the
engine OFF.

6.

Turn OFF the ignition for 10 seconds.

7.

Perform 5 and 6 three times. The accumulated
fuel of three ignition cycles must be more than
300cc. (Normal amount is more than 100cc
per one ignition cycle.)

Is enough amount of fuel discharged?

—

System OK

Go to Step 22

22

1.

Remove the fuel pump from the fuel tank.
Refer to Fuel Gauge Unit in the Fuel System
section.

2.

Inspect the fuel pump for any type of
restriction or damage on the fuel pipes.

3.

Repair or replace as necessary.

Did you find and correct the condition?

—

Go to Step 25

Go to Step 24

23

Replace the fuel pump resistor.

Did you complete the replacement?

—

Go to Step 25

—

24

Replace the fuel pump. Refer to Fuel Gauge Unit in
the Fuel System section.

Did you complete the replacement?

—

Go to Step 25

—

25

Reconnect all previously disconnected
components, fuse, relay or harness connector(s).

Did you complete the action?

—

Go to Step 3

—

Step

Action

Value(s)

Yes

No

6E-314   ENGINE CONTROL SYSTEM (4JK1/4JJ1)

Cruise Control System Check

Description

The cruise control system consists of the ECM, the
cruise main switch, set/ coast switch, resume/ accel.
switch and cancel switch. The cruise control keeps the
vehicle speed at a driver's set speed. When the cruise
main switch is turned ON, signal is provided to the
ECM and the cruise main indicator lamp on the switch
will light up. When the cruise set/ coast switch is turned
ON, the switch signal is provided to the ECM and the
vehicle speed is set. The vehicle speed is increased or
decreased if the set/ coast switch or the resume/ accel.
switch is turned ON. When the cruise cancel switch is
applied, the switch signal is provided to the ECM and
the cruise control system is inactive.

Condition for Running the Cruise Control

• The vehicle speed is between approximately 40

km/h (24 MPH) to 175 km/h (105 MPH).

• The engine speed is less than 4500 PRM.

• The cruise main switch is ON.

1. Function of "SET"
If the set/ coast switch is pressed and released while
condition for running the cruise control are satisfied, the
ECM memorize and maintain the vehicle speed at that
time.
2. Function of "COAST"
If the set/ coast switch is pressed while the cruise
control system is operating, the vehicle speed is
decreased. Then, when the set/ coast switch is
released, the vehicle will maintain the vehicle speed at
that time.
3. Function of "RESUME"
If the resume/ accel. switch is applied while the cruise
control system is operating and the ECM memorizes
the vehicle speed, the vehicle speed is returned to the
vehicle speed memorized by the ECM.
4. Function of "ACCEL"
If the resume/ accel. switch is applied while the cruise
control system is operating, the vehicle speed is
increased. Then, when the resume/ accel. switch is
released, the vehicle will maintain the vehicle speed at
that time.
5. Function of "TAP UP"
If the resume/ accel. switch is tapped (momentarily
applied) while the cruise control system is operating,
the vehicle speed is increased 1 km/h (0.6 MPH) at a
time.

6. Function of "TAP DOWN"
If the set/ coast switch is tapped while the cruise control
system is operating, the vehicle speed is decreased 1
km/h (0.6 MPH).
7. Function of Temporary Acceleration
If the accelerator pedal is pressed while the cruise
control system is operating, the vehicle speed is
increased.
8. Function of Temporary Cancellation
The cruise control is canceled temporarily if any of the
following condition is met:

• The cruise cancel switch is applied.

• The brake pedal is depressed.

• The clutch pedal is depressed (M/T).

• The selector lever position is not D, 3, 2 or L (A/T).

• The cruise set/ coast switch and resume/ accel.

switch are ON at the same time.

• The actual vehicle speed becomes less than

approximately 35 km/h (22 MPH).

• The actual vehicle speed is more than 40 km/h (24

MPH) over the set speed, or more than 10 km/h (6
MPH) over the set speed for longer than 3
minutes.

• The actual vehicle speed is more than 70 km/h (42

MPH) below the set speed, or more than 10 km/h
(6 MPH) below the set speed for 3 minutes.

By applying the resume/ accel. switch, the vehicle
speed is returned to the vehicle speed memorized by
the ECM (resume function) if within the condition for
running the cruise control are satisfied.
9. Function of Complete Cancellation
The cruise control is canceled completely if any of the
following condition is met:

• The cruise main switch is OFF.

• The ignition switch is OFF.

• The vehicle is once stopped.

• The DTCs relating to the cruise control system

inhibits are set.

Schematic Reference: Engine Controls Schematics

Connector End View Reference: Engine Controls
Connector End Views or ECM Connector End Views

Circuit/ System Testing Cruise Control System Check (1 of 2)

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