2007 ISUZU KB P190 engine

6E-210 Engine Control System (4JH1)
DTC P1520 (Symptom Code A) (Flash Code 47)
Circuit Description
(Manual Transmission)
The neutral switch is installed on the transmission gea
r
control box. W hen the gear position is neutral, the
switch is closed and the switch signal is provided to the
engine control module (ECM). If the ECM detects the
neutral switch signal is not changed from neutral during
the predetermined engine speed and vehicle speed
range, this DTC will set.
(Automatic Transmission)
The inhibitor switch is installed to the transmission case.
W hen the selector position is P or N range, the switch is
closed and the switch signal is provided to the Emir the
ECM detects the neutral switch signal is not changed
from P or N during the predetermined engine speed and
vehicle speed range, this DTC will set.
Condition for Running the DTC • The ignition switch is ON.
• The engine speed is higher than 1500 RPM.
• The vehicle speed is higher than 63 km/h (39
MPH) (M/T) or 78 km/h (49 MPH) (A/T).
• The clutch pedal is released. (M/T).

Condition for Setting the DTC
• The ECM detects that the neutral switch signal is
continuously ON (neutral or P/N range) during
three consecutive driving cycles.
Action Taken When the DTC Sets
• The ECM illuminates the malfunction indicato
r
lamp (MIL) when the diagnostic runs and fails.
Condition for Clearing the MIL/DTC
Important: • Following conditions must be met two consecutive
driving cycles. (One driving cycle: Ignition switch
ON > Engine run > Vehicle run > Ignition switch
OFF for 10 seconds)
- The engine speed is higher than 1500 RPM
- The vehicle speed is higher than 63 km/h (39 MPH) (M/T) or 78 km/h (49 MPH) (A/T)
- The clutch pedal is released (M/T)

- Other than neutral or P/N range
- After the above procedure is done, a history
DTC clears after 40 consecutive driving cycles
without a fault. Or clear with the scan tool.
Diagnostic Aids
• If an intermittent condition is suspected, refer to
Intermittent Conditions in this section.

DTC P1520 (Symptom Code A) (Flash Code 47)
Schematic Reference: Engine Controls Schematics
Connector End View Reference: Engine Controls
Connector End Views or Engine Control Module (ECM)
Connector End Views

Chart for M/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 ON the ignition, with the engine OFF.
3. Observe the Neutral Switch parameter with the scan tool while shift to neutral and other
positions.
Does the scan tool indicate ON when the position is
neutral and OFF when other than the neutral? 

Go to Diagnostic Aids Go to Step 3
3 1. Turn OFF the ignition. 2. Disconnect the neutral switch harness connector.
3. Turn ON the ignition, with the engine OFF.
4. Observe the Neutral Switch parameter with the scan tool.
Does the scan tool indicate ON? 

Go to Step 4 Go to Step 5
4 1. Test the neutral switch input signal circuit between the engine control module (ECM) (pin
87 of C-57 connector) and the neutral switch (pin
1 of E-11 connector) 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 7 Go to Step 6

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ISUZU KB P190 2007

Engine Control System (4JH1) 6E-211
Step Action Value(s) Yes No
5 Replace the neutral switch. Refer to Neutral Switch
Replacement in Transmission Section.
Did you complete the replacement? 

Go to Step 7 
6 Important: Replacement ECM must be
programmed.
Replace the ECM. Refer to Engine Control Module
(ECM) 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.
Important: Following conditions must be met two
consecutive driving cycles before clear with the scan
tool. (One driving cycle: Ignition switch ON > Engine
run > Vehicle run > Ignition switch OFF for 10
seconds) • The engine speed is higher than 1500 RPM
• The vehicle speed is higher than 63 km/h
(39 MPH)
• The clutch pedal is released
• Other than neutral
3. Turn ON the ignition, with the engine OFF.
4. Observe the Neutral Switch parameter with the scan tool while shift to neutral and other
positions.
Does the scan tool indicate ON when the position is
neutral and OFF when other than the neutral? 

Go to Step 8 Go to Step 3
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 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
P0705 set? 

Go to Applicable
DTC in Automatic Transmission Section Go to Step 3
3 1. Install the scan tool. 2. Turn ON the ignition, with the engine OFF.
3. Observe the Neutral Switch parameter with the scan tool while shift to P or N and other
positions.
Does the scan tool indicate ON when the position is
P or N and OFF when other than the P or N? 

Go to Diagnostic Aids Go to Step 4

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ISUZU KB P190 2007

6E-212 Engine Control System (4JH1)
Step Action Value(s) Yes No
4 1. Check to ensure the inhibitor switch is adjusted
correctly.
2. Adjust the inhibitor switch as necessary. Refer to Inhibitor Switch Adjustment in Automatic
Transmission Section.
Did you find and correct the condition? 

Go to Step 7 Go to Step 5
5 1. Test the P & N position switch signal circuit between the engine control module (ECM) (pin
87 of C-57 connector) and the diode (pin 2 of X-
16 connector) 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 7 Go to Step 6
6 Important: Replacement ECM must be
programmed.
Replace the ECM. Refer to Engine Control Module
(ECM) 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.
Important: Following conditions must be met two
consecutive driving cycles before clear with the scan
tool. (One driving cycle: Ignition switch ON > Engine
run > Vehicle run > Ignition switch OFF for 10
seconds) • The engine speed is higher than 1500 RPM
• The vehicle speed is higher than 78 km/h
(49 MPH)
• Other than P/N range
3. Turn ON the ignition, with the engine OFF.
4. Observe the Neutral Switch parameter with the scan tool while shift to P or N and other
positions.
Does the scan tool indicate ON when the position is
P or N and OFF when other than the P or N? 

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


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ISUZU KB P190 2007

Engine Control System (4JH1) 6E-213
DTC P1520 (Symptom Code B) (Flash Code 47)
Circuit Description
The neutral switch is installed on the transmission gea
r
control box. W hen the gear position is neutral, the
switch is closed and the switch signal is provided to the
engine control module (ECM). If the ECM detects the
neutral switch signal is not changed from other than
neutral during the predetermined engine speed and
vehicle speed range, this DTC will set. This DTC runs
only manual transmission.
Condition for Running the DTC

• The ignition switch is ON.
• The engine speed is higher than 665 RPM
• The vehicle speed is lower than 2 km/h (1.2 MPH).
• The clutch pedal is released after once depressed.
Condition for Setting the DTC • The ECM detects that the neutral switch signal is
continuously OFF (other than neutral) during three
consecutive driving cycles.
Action Taken When the DTC Sets • The ECM illuminates the malfunction indicato
r
lamp (MIL) when the diagnostic runs and fails.
Condition for Clearing the MIL/DTC
Important: • Following conditions must be met two consecutive
driving cycles. (One driving cycle: Ignition switch
ON > Engine run > Ignition switch OFF for 10
seconds)
- The engine speed is higher than 665 RPM
- The vehicle speed is lower than 2 km/h (1.2 MPH)
- The clutch pedal is released after once depressed
- Neutral position

- After the above procedure is done, a history
DTC clears after 40 consecutive driving cycles
without a fault. Or clear with the scan tool.
Diagnostic Aids
• If an intermittent condition is suspected, refer to
Intermittent Conditions in this section.

DTC P1520 (Symptom Code B) (Flash Code 47)
Schematic Reference: Engine Controls Schematics
Connector End View Reference: Engine Controls
Connector End Views or Engine Control Module (ECM)
Connector End Views

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 ON the ignition, with the engine OFF.
3. Observe the Neutral Switch parameter with the scan tool while shift to neutral and other
positions.
Does the scan tool indicate ON when the position is
neutral and OFF when other than the neutral? 

Go to Diagnostic Aids Go to Step 3
3 1. Turn OFF the ignition. 2. Inspect the ECM (10A) fuse (EB-4) in the engine room fuse block.
Is the ECM (10A) fuse (EB-4) open? 

Go to Step 4 Go to Step 5
4 Replace the ECM (10A) fuse (EB-4). If the fuse continues to open, repair the short to ground on one
of the circuits that is fed by the ECM (10A) fuse (EB-
4) or replace the shorted attached component fed by
the ECM (10A) fuse (EB-4).
Did you complete the repair? 

Go to Step 13 

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ISUZU KB P190 2007

6E-214 Engine Control System (4JH1)
Step Action Value(s) Yes No
5 1. Turn OFF the ignition.
2. Disconnect the neutral switch harness connector.
3. Turn ON the ignition, with the engine OFF.
4. Observe the Neutral Switch parameter with the scan tool while momentarily jumping across the
neutral switch harness connectors between pin 1
of E-11 connector and pin 1 of E-12 connector.
Does the scan tool indicate ON when the circuit is
jumped and OFF when the circuit is not jumped? 

Go to Step 9 Go to Step 6
6 1. Connect a test lamp between the ignition voltage feed circuit of the neutral switch harness (pin 1 of
E-12 connector) and a known good ground.
2. Turn ON the ignition, with the engine OFF.
Does the test lamp illuminate? 

Go to Step 8 Go to Step 7
7 Repair the open circuit or high resistance on the ignition voltage feed circuit between the ECM (10A)
fuse (EB-4) and the neutral switch (pin 1 of E-12
connector).
Did you complete the repair? 

Go to Step 13 
8 1. Test the neutral switch signal circuit between the
engine control module (ECM) (pin 87 of C-57
connector) and the neutral switch (pin 1 of E-11
connector) for an open circuit or high resistance.
2. Repair the circuit(s) as necessary.
Did you find and correct the condition? 

Go to Step 13 Go to Step 10
9 1. Turn OFF the ignition. 2. Inspect for an intermittent and for poor connections at the harness connectors of the
neutral switch (pin 1 of E-11 connector and pin 1
of E-12 connector).
3. Repair the connection(s) as necessary.
Did you find and correct the condition? 

Go to Step 13 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 neutral switch circuit at the
harness connector of the ECM (pin 87 of C-57
connector).
4. Repair the connection(s) as necessary.
Did you find and correct the condition? 

Go to Step 13 Go to Step 12
11 Replace the neutral switch. Refer to Neutral Switch Replacement in Transmission Section.
Did you complete the replacement? 

Go to Step 13 
12 Important: Replacement ECM must be
programmed.
Replace the ECM. Refer to Engine Control Module
(ECM) Replacement in this section.
Did you complete the replacement? 

Go to Step 13 

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ISUZU KB P190 2007

Engine Control System (4JH1) 6E-215
Step Action Value(s) Yes No
13 1. Reconnect all previously disconnected harness
connector(s).
2. Clear the DTCs with the scan tool.
Important: Following conditions must be met two
consecutive driving cycles before clear with the scan
tool. (One driving cycle: Ignition switch ON > Engine
run > Ignition switch OFF for 10 seconds) • The engine speed is higher than 665 RPM
• The vehicle speed is lower than 2 km/h (1.2
MPH)
• The clutch pedal is released after once
depressed
• Neutral position
3. Turn ON the ignition, with the engine OFF.
4. Observe the Neutral Switch parameter with the scan tool while shift to neutral and other
positions.
Does the scan tool indicate ON when the position is
neutral and OFF when other than the neutral? 

Go to Step 14 Go to Step 3
14 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



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ISUZU KB P190 2007

6E-216 Engine Control System (4JH1)
DTC P1605 (Symptom Code C, D, E) (Flash Code 55)
Circuit Description
This diagnostic applies to internal microprocesso
r
integrity conditions within the engine control module
(ECM). The electronically erasable programmable read
only memory (EEPROM) memorize some data fo
r
engine control and communication with other control
module. If the ECM detects memory area malfunction
inside of the ECM, this DTC will set.
Condition for Setting the DTC
• The ECM detects internal seed or key file in
EEPROM data is destroyed (Symptom Code C).
• The ECM detects reading or writing from the
EEPROM data is failed during initialization
(Symptom Code D).
• The ECM detects total sum of EEPROM data is
not equal to registered value during initialization
(Symptom Code E).
Action Taken When the DTC Sets
• The ECM illuminates the malfunction indicato
r
lamp (MIL) when the diagnostic runs and fails.
• The ECM uses default EPROM data substitution o
f
faulty EEPROM. (Symptom Code D & E).
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.

DTC P1605 (Symptom Code C, D, E) (Flash Code 55)

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. Monitor the Diagnostic Trouble Code (DTC) Information with the scan tool.
Does the DTC fail this ignition? 

Go to Step 3 Go to Step 4
3 Important: Replacement ECM must be
programmed.
Replace the ECM. Refer to Engine Control Module
(ECM) Replacement in this section.
Did you complete the replacement? 

Go to Step 4 
4 1. Clear the DTCs with the scan tool.
2. Turn OFF the ignition for 30 seconds.
3. Turn ON the ignition, with the engine OFF.
4. Monitor the DTC Information with the scan tool.
Did the DTC fail this ignition? 

Go to Step 3 Go to Step 5
5 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


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ISUZU KB P190 2007

Engine Control System (4JH1) 6E-217
DTC P1610 (Symptom Code A) (Flash Code 56)
Circuit Description
The electronically erasable programmable read onl
y
memory (EEPROM) memorize immobilizer securit
y
code and secret key for communication with the
immobilizer control unit (ICU). If the engine control
module (ECM) detects immobilizer functions are not
programmed into the ECM, this DTC will set.
Condition for Setting the DTC
• The ECM detects immobilizer security code and
secret key is not programmed.

Action Taken When the DTC Sets
• The ECM illuminates the malfunction indicato
r
lamp (MIL) when the diagnostic runs and fails.
• The desired fuel injection quantity is set 0 mg/strk.
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 • Non programmed ECM may set this DTC.
• ECM with wrong specification may set this DTC.

DTC P1610 (Symptom Code A) (Flash Code 56)

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. Monitor the Diagnostic Trouble Code (DTC) Information with the scan tool.
Does the DTC fail this ignition? 

Go to Step 3 Go to Diagnostic
Aids
3 Program or reprogram immobilizer function into the engine control module (ECM). Refer to Programming
Engine Control Module (ECM) in immobilizer section.
Did you find and correct the condition? 

Go to Step 5 Go to Step 4
4 Important: Replacement ECM must be
programmed.
Replace the ECM. Refer to Engine Control Module
(ECM) Replacement in this section.
Did you complete the replacement? 

Go to Step 5 
5 1. Clear the DTCs with the scan tool.
2. Turn OFF the ignition for 30 seconds.
3. Turn ON the ignition, with the engine OFF.
4. Monitor the DTC Information with the scan tool.
Did the DTC fail this ignition? 

Go to Step 3 Go to Step 6
6 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


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ISUZU KB P190 2007