Isuzu KB P190. Manual - part 448

ENGINE CONTROL SYSTEM (4JK1/4JJ1)   6E-175

10

1.

Inspect for an intermittent and for poor
connections at the harness connector of the
VSS (pin 1, 2 and 3 of E-44).

2.

Repair the connection(s) as necessary.

Did you find and correct the condition?

—

Go to Step 15

Go to Step 12

11

1.

Turn OFF the ignition.

2.

Disconnect the ECM harness connector.

3.

Inspect for an intermittent and for a poor
connection at the harness connector of the
ECM (pin 62 of C-58).

4.

Repair the connection(s) as necessary.

Did you find and correct the condition?

—

Go to Step 15

Go to Step 14

12

1.

Inspect the VSS, drive gear, driven gear or
output shaft for the following conditions:

• Physical damage of sensor, drive gear or

driven gear

• Loose or improper installation of sensor,

drive gear or driven gear

• Transmission output shaft teeth damage

• Excessive transmission output shaft play

• Transfer output shaft teeth damage

• Excessive transfer output shaft play

2.

Repair or replace as necessary.

Did you find and correct the condition?

—

Go to Step 15

Go to Step 13

13

Replace the VSS. Refer to VSS Replacement.

Did you complete the replacement?

—

Go to Step 15

—

14

Important: Replacement ECM must be
programmed and learned.
Replace the ECM. Refer to ECM Replacement.

Did you complete the replacement?

—

Go to Step 15

—

15

1.

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

2.

Clear the DTCs with a scan tool.

3.

Turn OFF the ignition for 30 seconds.

4.

Drive the vehicle while observing the Vehicle
Speed parameter with a scan tool.

Does the scan tool indicate correct vehicle speed?

—

Go to Step 16

Go to Step 4

16

Observe the DTC Information with a scan tool.

Are there any DTCs that you have not diagnosed?

—

Go to DTC List

System OK

Step

Action

Value(s)

Yes

No

6E-176   ENGINE CONTROL SYSTEM (4JK1/4JJ1)

DTC P0501 (Flash Code 25)

Circuit Description

The vehicle speed sensor (VSS) is used by the ECM
and speedometer, which generates a speed signal from
the transmission output shaft rotational speed or
transfer output shaft rotational speed. The sensor has
the following circuits.

• Ignition voltage feed circuit

• Low reference circuit

• VSS signal circuit

The VSS uses a hall effect element. It interacts with the
magnetic field created by the rotating magnet and
outputs square wave pulse signal. The ECM calculates
the vehicle speed by the VSS. If the 2WD fitted with
Jatco automatic transmission, VSS signals are sent
from the TCM. If the ECM detects VSS signals are
sharply changed, this DTC will set.

Condition for Running the DTC

• The ignition voltage is more than 9 volts.

• The ignition switch is ON.

Condition for Setting the DTC

• The ECM detects that the VSS signal are changed

larger than a predetermined vehicle speed within a
very short calibrated time.

Action Taken When the DTC Sets

• The ECM illuminates the MIL when the diagnostic

runs and fails. Refer to DTC Type Definitions for
Action Taken When the DTC Sets - Type A.

• The ECM inhibits cruise control.

Condition for Clearing the DTC

• Refer to DTC Type Definitions for Condition for

Clearing the MIL/ DTC - Type A.

Diagnostic Aids

• If an intermittent condition is suspected, refer to

Intermittent Conditions in this section.

• Electromagnetic interference in the VSS circuits

may set this DTC.

Notice:

• If this DTC set, the Vehicle Speed parameter on

the scan tool will display 3 km/h (2 MPH).

Schematic Reference: Engine Controls Schematics

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

Circuit/ System Testing DTC P0501

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.

Inspect all of the circuits going to the vehicle
speed sensor (VSS) for the following
conditions:

• Routed too closely to fuel injection wiring

or components

• Routed too closely to after-market add-

on electrical equipment

• Routed too closely to solenoids, relays,

and motors

2.

If you find incorrect routing, correct the
harness routing.

Did you find and correct the condition?

—

Go to Step 8

Go to Step 3

3

1.

Inspect for an intermittent, for poor
connections and corrosion at the Meter (10A)
fuse.

2.

Repair the connection(s) as necessary.

Did you find and correct the condition?

—

Go to Step 8

Go to Step 4

4

1.

Inspect for an intermittent, a poor connection
and corrosion at the ground terminal (E-10).

2.

Repair the connection(s) as necessary.

Did you find and correct the condition?

—

Go to Step 8

Go to Step 5

ENGINE CONTROL SYSTEM (4JK1/4JJ1)   6E-177

5

1.

Turn OFF the ignition.

2.

Disconnect the VSS harness connector.

3.

Inspect for an intermittent, for poor
connections and corrosion at the harness
connector of the VSS (pins 1, 2 and 3 of E-
44).

4.

Disconnect the ECM harness connector.

5.

Inspect for an intermittent, for a poor
connection and corrosion at the harness
connector of the ECM (pin 62 of C-58).

6.

Repair the connection(s) as necessary.

Did you find and correct the condition?

—

Go to Step 8

Go to Step 6

6

1.

Inspect the VSS, drive gear, driven gear or
output shaft for the following conditions:

• Physical damage of sensor, drive gear or

driven gear

• Loose or improper installation of sensor,

drive gear or driven gear

• Transmission output shaft teeth damage

• Excessive transmission output shaft play

• Transfer output shaft teeth damage

• Excessive transfer output shaft play

2.

Repair or replace as necessary.

Did you find and correct the condition?

—

Go to Step 8

Go to Step 7

7

Replace the VSS. Refer to VSS Replacement.

Did you complete the replacement?

—

Go to Step 8

—

8

1.

Reconnect all previously disconnected
harness connector(s).

2.

Clear the DTCs with a scan tool.

3.

Turn OFF the ignition for 30 seconds.

4.

Drive the vehicle while observing the Vehicle
Speed with a scan tool.

Does the scan tool parameter indicate correct
vehicle speed?

—

Go to Step 9

Go to Step 2

9

Observe the DTC Information with a scan tool.

Are there any DTCs that you have not diagnosed?

—

Go to DTC List

System OK

Step

Action

Value(s)

Yes

No

6E-178   ENGINE CONTROL SYSTEM (4JK1/4JJ1)

DTC P0512 (Flash Code 417)

Circuit Description

The starter switch signal is inputted to the ECM during
the ignition switch START position. If the ECM detects
the starter switch signal continuously ON during the
engine running, this DTC will set.

Condition for Running the DTC

• The ignition switch is ON.

• The engine is running.

Condition for Setting the DTC

• The ECM detects that the starter switch signal is

stuck at the ON position (high voltage) for longer
than 20 seconds.

Action Taken When the DTC Sets

• The ECM illuminates the SVS lamp when the

diagnostic runs and fails. Refer to DTC Type
Definitions for Action Taken When the DTC Sets -
Type C.

Condition for Clearing the DTC

• Refer to DTC Type Definitions for Condition for

Clearing the SVS Lamp/ DTC - Type C.

Diagnostic Aids

• If an intermittent condition is suspected, refer to

Intermittent Conditions in this section.

Notice:

• This DTC will set if the ignition switch continues

being START position for longer than 20 seconds.

Schematic Reference: Engine Controls Schematics

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

Circuit/ System Testing DTC P0512

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.

Turn OFF the ignition.

2.

Remove the starter cut relay in order to inhibit
starter motor engagement at ignition switch
ON.

3.

Install a scan tool.

4.

Turn ON the ignition, with the engine OFF.

5.

Observe the Starter Switch parameter with a
scan tool.

Does the Starter Switch parameter indicate OFF?

—

Go to Diagnostic 

Aids

Go to Step 3

3

Remove the Starter (10A) fuse in the cabin fuse
block.

Does the Starter Switch parameter indicate OFF?

—

Go to Step 4

Go to Step 5

4

1.

Test the signal circuit between the starter
switch (pin 1 of B-63) and each terminal of the
ignition switch (pins 1, 2, 3 and 4 of B-62 and
pin 3 of B-63) for short circuit each other at the
ignition switch ON.

2.

Repair the circuit(s) as necessary.

Did you find and correct the condition?

—

Go to Step 8

Go to Step 7

5

1.

Test the signal circuit between the ECM (pin
44 of C-58) and the Starter (10A) fuse or
starter relay (pin 3 of X-8) for a short to battery
or ignition voltage.

2.

Repair the circuit(s) as necessary.

Did you find and correct the condition?

—

Go to Step 8

Go to Step 6