Isuzu KB P190. Manual - part 286

6E-110  Engine Control System (4JH1) 

Step Action 

Value(s) 

Yes 

No 

16 

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 

 

Engine Control System (4JH1)  6E-111 

DTC P0243 (Symptom Code 4) (Flash Code 64) 

Circuit Description 
The engine control module (ECM) controls the
turbocharger wastegate valve based on the barometric 
pressure in order to reduce turbocharger spinning
speeds at high altitude area. The ECM controls the
turbocharger wastegate valve diaphragm by acting the
regulated vacuum pressure via controlling the solenoid 
valve. The vacuum pressure sensor monitors the
regulated vacuum pressure to the turbocharger
wastegate valve. The ECM calculates desired vacuum
pressure and it compares the calculated desired
vacuum pressure to the actual value to determine the
solenoid valve position. When the actual vacuum
pressure is higher than the desired value, the solenoid
valve is closed to decrease the vacuum pressure. If the 
ECM detects that an open circuit or short to ground on 
the turbocharger solenoid valve control circuit, this DTC
will set. 
Condition for Running the DTC 

•  The ignition switch is ON. 

Condition for Setting the DTC 

•  The ECM detects that the low voltage condition on

the turbocharger solenoid valve control circuit for
longer than 3 seconds when the solenoid valve is 
commanded OFF. 

 

Action Taken When the DTC Sets 

•  The ECM illuminates the malfunction indicator 

lamp (MIL) when the diagnostic runs and fails. 

•  The ECM limits fuel injection quantity. 
•  The ECM uses a turbocharger solenoid valve 

control substitution of 68%. 

•  The ECM uses an EGR solenoid valve control

substitution of 10%. 

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 

•  If an intermittent condition is suspected, refer to 

Intermittent Conditions in this section. 

 
DTC P0243 (Symptom Code 4) (Flash Code 64) 
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 OFF the ignition for 30 seconds. 
3.  Start the engine. 
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 

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 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 15 

 

5 

1.  Turn OFF the ignition. 
2. Disconnect the turbocharger solenoid valve 

harness connector. 

3.  Connect a test lamp between the voltage feed 

circuit of the turbocharger solenoid valve harness 
(pin 1 of C-123 connector) and a known good 
ground. 

4.  Turn ON the ignition, with the engine OFF. 
Does the test lamp illuminate? 

 

Go to Step 6 

Go to Step 8 

6E-112  Engine Control System (4JH1) 

Step Action 

Value(s) 

Yes 

No 

6 

1.  Connect a test lamp between the control circuit 

of the turbocharger solenoid valve harness (pin 2 
of C-123 connector) and battery voltage. 

2.  Turn ON the ignition, with the engine OFF. 
Does the test lamp continuously illuminate? 

 

Go to Step 9 

Go to Step 7 

7 

1.  Keep the test lamp with connected. 
2.  Turn OFF the ignition. 
3.  Disconnect the vacuum pressure sensor harness 

connector in order to energize the turbocharger 
solenoid valve. 

4.  Turn ON the ignition, with the engine OFF. 
Does the test lamp blink?  

 

Go to Step 11 

Go to Step 10 

8 

Repair the open circuit or high resistance on the 
voltage feed circuit between the ECM (10A) fuse 
(EB-4) and the turbocharger solenoid valve (pin 1 of 
C-123 connector). 
Did you complete the repair? 

 

Go to Step 15 

 

9 

1. Test the control circuit between the engine 

control module (ECM) (pin 97 of C-57 connector) 
and the turbocharger solenoid valve (pin 2 of C-
115 connector) for a short to ground. 

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

 

Go to Step 15 

Go to Step 14 

10 

1.  Test the control circuit between the ECM (pin 96 

of C-57 connector) and the turbocharger solenoid 
valve (pin 2 of C-123 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 15 

Go to Step 12 

11 

1.  Turn OFF the ignition. 
2. Disconnect the turbocharger solenoid valve 

harness connector. 

3. Inspect for an intermittent and for poor 

connections at the harness connector of the 
turbocharger solenoid valve (pins 1 and 2 of C-
123 connector). 

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

 

Go to Step 15 

Go to Step 13 

12 

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

connection on the turbocharger solenoid valve 
circuit at the harness connector of the ECM (pin 
96 of C-57 connector). 

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

 

Go to Step 15 

Go to Step 14 

13 

Replace the turbocharger solenoid valve. Refer to 
Turbocharger Solenoid Valve Replacement in this 
section. 
Did you complete the replacement? 

 

Go to Step 15 

 

14 

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 15 

 

Engine Control System (4JH1)  6E-113 

Step Action 

Value(s) 

Yes 

No 

15 

1.  Reconnect all previously disconnected fuse or 

harness connector(s). 

2.  Clear the DTCs with the scan tool. 
3.  Turn OFF the ignition for 30 seconds. 
4.  Start the engine. 
5.  Monitor the DTC Information with the scan tool. 
Did the DTC fail this ignition? 

 

Go to Step 3 

Go to Step 16 

16 

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