Isuzu KB P190. Manual - part 305

6E-186  Engine Control System (4JH1) 

Step Action 

Value(s) 

Yes 

No 

6 

1.  Turn OFF the ignition. 
2. Disconnect the clutch pedal switch harness 

connector. 

3.  Turn ON the ignition, with the engine OFF. 
4.  Observe the Clutch Pedal Switch parameter with 

the scan tool while momentarily jumping across 
the clutch pedal switch harness connector 
between pins 1 and 2 of C-77 connector. 

Does the scan tool indicate Applied when the circuit 
is jumped and Released when the circuit is not 
jumped? 

 

Go to Step 12 

Go to Step 7 

7 

1.  Connect a test lamp between the ignition voltage 

feed circuit of the clutch pedal switch harness 
(pin 1 of C-77 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 9 

8 

1.  Connect a test lamp between the signal circuit of 

the clutch pedal switch harness (pin 2 of C-77 
connector) and a known good ground. 

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

 

Go to Step 10 

Go to Step 11 

9 

Repair the open circuit or high resistance on the 
ignition voltage feed circuit between the ECM (10A) 
fuse (EB-4) and the clutch pedal switch (pin 1 of C-
77 connector). 
Did you complete the repair? 

 

Go to Step 16 

 

10  1. Test the clutch pedal switch signal circuit 

between the engine control module (ECM) (pin 
31 of C-56 connector) and the clutch pedal 
switch (pin 2 of C-77 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 16 

Go to Step 15 

11  1. Test the clutch pedal switch signal circuit 

between the ECM (pin 31 of C-56 connector) and 
the clutch pedal switch (pin 2 of C-77 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 16 

Go to Step 13 

12 

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

connections at the harness connector of the 
clutch pedal switch (pins 1 and 2 of C-77 
connector). 

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

 

Go to Step 16 

Go to Step 14 

13 

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

connection on the clutch pedal switch circuit at 
the harness connector of the ECM (pin 31 of C-
56 connector). 

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

 

Go to Step 16 

Go to Step 15 

Engine Control System (4JH1)  6E-187 

Step Action 

Value(s) 

Yes 

No 

14 

Replace the clutch pedal switch. Refer to Clutch 
Pedal Switch Replacement in this section. 
Did you complete the replacement? 

 

Go to Step 16 

 

15 

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 16 

 

16 

1.  Reconnect all previously disconnected fuse or 

harness connector(s). 

2.  Clear the DTCs with the scan tool. 
3.  Turn ON the ignition, with the engine OFF. 
4.  Observe the Clutch Pedal Switch parameter with 

the scan tool while fully depressing and releasing 
the clutch pedal. 

Does the scan tool indicate Applied when the clutch 
pedal is applied and Released when the clutch pedal 
is released? 

 

Go to Step 17 

Go to Step 3 

17 

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-188  Engine Control System (4JH1) 

DTC P1105 (Symptom Code 1) (Flash Code 86) 

Circuit Description 
The barometric pressure (BARO) sensor is installed
inside of the engine control module (ECM) and converts 
the BARO into a voltage signal. The ECM uses this
voltage signal to calibrate the fuel injection quantity and
injection timing for altitude compensation. If the ECM
detects an excessively high BARO sensor signal 
voltage, this DTC will set. 
Condition for Running the DTC 

•  The ignition switch is ON.

 

Condition for Setting the DTC 

•  The ECM detects that the BARO sensor signal

voltage is more than 4.4 volts for 1 second. 

 

Action Taken When the DTC Sets 

•  The ECM illuminates the malfunction indicator 

lamp (MIL) when the diagnostic runs and fails. 

•  The ECM uses a BARO substitution of 1013 hPa.

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 P1105 (Symptom Code 1) (Flash Code 86) 
 

 

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 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.  Start the engine. 
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 

 

Engine Control System (4JH1)  6E-189 

DTC P1105 (Symptom Code 2) (Flash Code 86) 

Circuit Description 
The barometric pressure (BARO) sensor is installed
inside of the engine control module (ECM) and converts 
the BARO into a voltage signal. The ECM uses this
voltage signal to calibrate the fuel injection quantity and
injection timing for altitude compensation. If the ECM
detects an excessively low BARO sensor signal voltage,
this DTC will set. 
Condition for Running the DTC 

•  The ignition switch is ON.

 

Condition for Setting the DTC 

•  The ECM detects that the BARO sensor signal

voltage is less than 1.5 volts for 1 second. 

 

Action Taken When the DTC Sets 

•  The ECM illuminates the malfunction indicator 

lamp (MIL) when the diagnostic runs and fails. 

•  The ECM uses a BARO substitution of 1013 hPa.

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 P1105 (Symptom Code 2) (Flash Code 86) 
 

 

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 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.  Start the engine. 
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