Isuzu KB P190. Manual — part 298

6E-158 Engine Control System (4JH1)

Step Action

Value(s)

Yes

No

4

1. Turn OFF the ignition.
2. Disconnect the engine control module (ECM)

harness connector.

3. Inspect for an intermittent and for a poor

connection on A/T VSS circuit at the harness
connector of the ECM (pin 68 of C-56 connector).

4. Repair the connection(s) as necessary.
Did you find and correct the condition?



Go to Step 7

Go to Step 5

5

1. Remove the A/T VSS. Refer to A/T Speed

Sensor Replacement in automatic transmission
section.

2. Visually inspect the A/T VSS for the following

conditions:

• Physical

damage

• Being

loose

• Improper

installation

3. The following conditions may cause this DTC to

set:

• Electromagnetic interference in the A/T

VSS circuits

4. Repair or replace as necessary.
Did you find and correct the condition?



Go to Step 7

Go to Step 6

6

Replace the A/T VSS. Refer to A/T Speed Sensor
Replacement in automatic transmission section
Did you complete the replacement?



Go to Step 7



7

1. Reconnect all previously disconnected harness

connector(s).

2. Clear the DTCs with the scan tool.
3. Turn OFF the ignition for 30 seconds.
4. Drive the vehicle.
5. Observe the Vehicle Speed parameter with the

scan tool.

Does the Vehicle Speed parameter indicate correct
vehicle speed?



Go to Step 8

Go to Step 2

8

Observe the DTC Information with the scan tool.
Are there any DTCs that you have not diagnosed?



Go to Diagnostic

Trouble Code (DTC)

List System

OK

Chart for except 2WD with A/T

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:

• Routed too closely to fuel injection solenoid

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 7

Go to Step 3

Engine Control System (4JH1) 6E-159

Step Action

Value(s)

Yes

No

3

1. Turn OFF the ignition.
2. Disconnect the VSS harness connector.
3. Inspect for an intermittent and for poor

connections at the harness connector of the VSS
(pins 1, 2 and 3 of E-44 connector).

4. Repair the connection(s) as necessary.
Did you find and correct the condition?



Go to Step 7

Go to Step 4

4

1. Turn OFF the ignition.
2. Disconnect the engine control module (ECM)

harness connector.

3. Inspect for an intermittent and for a poor

connection on VSS circuit at the harness
connector of the ECM (pin 68 of C-56 connector).

4. Repair the connection(s) as necessary.
Did you find and correct the condition?



Go to Step 7

Go to Step 5

5

1. Remove the VSS. Refer to Vehicle Speed

Sensor (VSS) Replacement in this section.

2. Visually inspect the VSS for the following

conditions:

• Physical

damage

• Being

loose

• Improper

installation

3. The following conditions may cause this DTC to

set:

• Electromagnetic interference in the VSS

circuits

4. Repair or replace as necessary.
Did you find and correct the condition?



Go to Step 7

Go to Step 6

6

Replace the VSS. Refer to Vehicle Speed Sensor
(VSS) Replacement in this section.
Did you complete the replacement?



Go to Step 7



7

1. Reconnect all previously disconnected harness

connector(s).

2. Clear the DTCs with the scan tool.
3. Turn OFF the ignition for 30 seconds.
4. Drive the vehicle.
5. Observe the Vehicle Speed parameter with the

scan tool.

Does the Vehicle Speed parameter indicate correct
vehicle speed?



Go to Step 8

Go to Step 2

8

Observe the DTC Information with the scan tool.
Are there any DTCs that you have not diagnosed?



Go to Diagnostic

Trouble Code (DTC)

List System

OK

6E-160 Engine Control System (4JH1)

DTC P0500 (Symptom Code B) (Flash Code 24)

Circuit Description
The vehicle speed sensor (VSS) is used by the engine
control module (ECM) and speedometer, which
generates a speed signal from the transmission output
shaft. The VSS has the following circuits.

• Ignition voltage feed circuit
• VSS signal circuit
• VSS low reference 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 12 volts
operating supply from the Meter fuse (except 2WD with
A/T) or Back Up fuse (2WD with A/T). The ECM
calculates the vehicle speed by the VSS. If the vehicle
is 2WD with automatic transmission, VSS signals are
sent from the transmission control module (TCM). If the
ECM detects VSS signals are not generated, this DTC
will set.
Condition for Running the DTC

• The ignition switch is ON.
• The engine speed is higher than 3600 RPM.
• The fuel injection quantity is more than 41 mg/strk.

Condition for Setting the DTC

• The ECM detects that the vehicle speed is lower

than 1.5 km/h (1 MPH) for 60 seconds.

Action Taken When the DTC Sets

• The ECM illuminates the malfunction indicator

lamp (MIL) when the diagnostic runs and fails.

Condition for Clearing the MIL/DTC

• The ECM turns OFF the MIL when the diagnostic

runs and does not fail.

• A history DTC clears after 40 consecutive driving

cycles without a fault. Or clear with the scan tool.

Diagnostic Aids

• Electrical or magnetic interference may affect

intermittent condition.

• If an intermittent condition is suspected, refer to

Intermittent Conditions in this section.

DTC P0500 (Symptom Code B) (Flash Code 24)
Schematic Reference: Engine Controls Schematics
Connector End View Reference: Engine Controls
Connector End Views or Engine Control Module (ECM)
Connector End Views

Chart for 2WD with A/T

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 the scan tool.
2. Turn OFF the ignition for 30 seconds.
3. Turn ON the ignition, with the engine OFF.
4. Select the “JR405E Automatic Transmission” in

the system selection menu.

5. Monitor the Read Diagnostic Trouble Code

(DTC) Info As Stored By ECU with the scan tool.

Does the transmission control module (TCM) DTC
P0722 set?



Go to Applicable

DTC in Automatic

Transmission

Section

Go to Step 3

3

1. Drive the vehicle.
2. Select the data display function of engine control

module (ECM).

3. Observe the Vehicle Speed parameter with the

scan tool.

Does the Vehicle Speed parameter indicate correct
vehicle speed?



Go to Diagnostic

Aids

Go to Step 4

4

1. Turn OFF the ignition.
2. Disconnect the TCM harness connector.
3. Turn ON the ignition, with the engine OFF.
4. Intermittently jump the VSS signal output circuit

(pin A-10 of C-94 connector) with a test lamp that
is connected to a known good ground while
monitoring the Vehicle Speed parameter with the
scan tool.

Does the scan tool indicate any vehicle speed when
the circuit is intermittently pulled to ground?



Go to Step 8

Go to Step 5

Engine Control System (4JH1) 6E-161

Step Action

Value(s)

Yes

No

5

1. Turn OFF the ignition.
2. Remove the instrument panel cluster (IPC) in

order to disconnect the B-23 harness connector.

3. Disconnect the IPC B-23 harness connector.
4. Turn ON the ignition, with the engine OFF.
5. Intermittently jump the signal output circuit of the

VSS signal output (pin 10 of B-23 connector) with
a test lamp that is connected to a known good
ground while monitoring the Vehicle Speed
parameter with the scan tool.

Does the scan tool indicate any vehicle speed when
the circuit is intermittently pulled to ground?



Go to Step 6

Go to Step 7

6

1. Test the VSS signal output circuit between the

IPC (pin 9 of B-23 connector) and the TCM (pin
A-10 of C-94 connector) for the following
conditions:

• An open circuit
• A short to ground
• A short to battery or ignition voltage
• High

resistance

2. Repair the circuit(s) as necessary.
Did you find and correct the condition?



Go to Step 14

Go to Step 9

7

1. Test the VSS signal output circuit between the

ECM (pin 68 of C-56 connector) and the IPC (pin
10 of B-23 connector) for the following
conditions:

• An open circuit
• A short to ground
• A short to battery or ignition voltage
• High

resistance

2. Repair the circuit(s) as necessary.
Did you find and correct the condition?



Go to Step 14

Go to Step 10

8

1. Turn OFF the ignition.
2. Inspect for an intermittent and for a poor

connection on the VSS signal circuit at the
harness connector of the TCM (pin A-10 of C-94
connector).

3. Repair the connection(s) as necessary.
Did you find and correct the condition?



Go to Step 14

Go to Step 12

9

1. Turn OFF the ignition.
2. Disconnect the IPC B-23 harness connector.
3. Inspect for an intermittent and for poor

connections on the VSS signal circuit at the
harness connector of the IPC (pins 9 and 10 of
B-24 connector).

4. Repair the connection(s) as necessary.
Did you find and correct the condition?



Go to Step 14

Go to Step 11

10

1. Turn OFF the ignition.
2. Disconnect the ECM harness connector.
3. Inspect for an intermittent and for a poor

connection on the VSS signal circuit at the
harness connector of the ECM (pin 68 of C-56
connector).

4. Repair the connection(s) as necessary.
Did you find and correct the condition?



Go to Step 14

Go to Step 13