2007 ISUZU KB P190 Circuit

Engine Control System (4JH1) 6E-233
Step Action Value(s) Yes No
13 1. Turn OFF the ignition.
2. Disconnect the PCU harness connector.
3. Inspect for an intermittent and for poor connections at the harness connector of the PCU
(pins 1 and 2 of E-6 connector).
4. Repair the connection(s) as necessary.
Did you find and correct the condition? 

Go to Step 17 Go to Step 15
14 1. Turn OFF the ignition. 2. Disconnect the ECM harness connector.
3. Inspect for an intermittent and for poor connections on the CAN Low or High circuits at
the harness connector of the ECM (pins 99 and
100 of C-57 connector).
4. Repair the connection(s) as necessary.
Did you find and correct the condition? 

Go to Step 17 Go to Step 16
15 Important: The fuel injection pump must be timed to
the engine.
Replace the fuel injection pump. Refer to Fuel
Injection Pump Replacement in engine mechanical
section. (PCU is part of the fuel injection pump
assembly)
Did you complete the replacement? 

Go to Step 17 
16 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 17 
17 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. Start the engine.
5. Monitor the DTC Information with the scan tool.
Does the DTC fail this ignition? 

Go to Step 3 Go to Step 18
18 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-234 Engine Control System (4JH1)
DTC P1690 (Symptom Code 4) (Flash Code 77)
Circuit Description
The malfunction indicator lamp (MIL) is located on the
instrument panel cluster (IPC). The battery voltage is
supplied to the MIL. The engine control module (ECM)
turns the MIL ON by grounding the MIL control circuit.
After a fixed time passes, the ECM turns OFF the MIL
with the ignition ON and the engine OFF. The MIL has
the following functions:
• The MIL informs the driver that a malfunction has
occurred and the vehicle should be taken in fo
r
service as soon as possible.
• The MIL illuminates during a bulb test and a
system test.
•
A DTC will be stored if a MIL is requested by the
ECM.
If the ECM detects an open circuit or short circuit on the
MIL control circuit, this DTC will set.
Condition for Running the DTC • The ignition switch is ON.
Condition for Setting the DTC

• The ECM detects a low voltage condition on the
MIL control circuit for longer than 3 seconds when
the MIL is commanded OFF.
Action Taken When the DTC Sets • The ECM does not illuminates the MIL when the
diagnostic runs and fails.
Condition for Clearing the DTC • 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 P1690 (Symptom Code 4) (Flash Code 77)
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. Perform the Malfunction Indicator Lamp (MIL) test with the scan tool.
4. Command the MIL ON with the scan tool.
Does the MIL turn ON when commanded ON with
the scan tool? 

Go to Step 3 Go to Step 4
3 Command the MIL OFF with the scan tool. Does the MIL OFF? 

Go to Step 17 Go to Step 10
4 1. Turn OFF the ignition.
2. Inspect the Meter (15A) fuse (C-14) in the cabin fuse block.
Is the Meter (15A) fuse (C-14) open? 

Go to Step 5 Go to Step 6
5 Replace the Meter (15A) fuse (C-14). If the fuse continues to open, repair the short to ground on one
of the circuits that fed by the Meter (15A) fuse (C-14)
or replace the shorted attached component fed by
the Meter (15A) fuse (C-14).
Did you complete the repair? 

Go to Step 19 
6 1. Turn OFF the ignition.
2. Disconnect the engine control module (ECM) harness connector.
3. Turn ON the ignition, with the engine OFF.
4. Connect a 3-amp fused jumper wire between the MIL control circuit of the ECM harness connector
(pin 42 of C-56 connector) and a known good
ground.
Does the MIL illuminate? 

Go to Step 11 Go to Step 7

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ISUZU KB P190 2007

Engine Control System (4JH1) 6E-235
Step Action Value(s) Yes No
7 1. Turn OFF the ignition.
2. Remove the instrument panel cluster (IPC).
3. Remove the MIL bulb from the IPC (meter assembly).
Is the MIL bulb burned out? 

Go to Step 15 Go to Step 8
8 1. Disconnect the IPC harness B-23 connector. 2. Connect a test lamp between the voltage feed circuit of the MIL (pin 30 of B-23 connector) and
a known good ground.
3. Turn ON the ignition, with the engine OFF.
Does the test lamp illuminate? 

Go to Step 9 Go to Step 12
9 1. Turn OFF the ignition. 2. Reconnect the ECM harness connector.
3. Connect a test lamp between the voltage feed circuit and control circuit of the MIL (pins 17 and
30 of B-23 connector).
4. Turn ON the ignition, with the engine OFF.
5. Perform the MIL test with the scan tool.
6. Command the MIL ON with the scan tool.
Does the test lamp turn ON when commanded ON
with the scan tool? 

Go to Step 14 Go to Step 13
10 1. Test the control circuit of the MIL between the ECM (pin 42 of C-56 connector) and the IPC (pin
17 of B-23 connector) for a short to ground.
2. Repair the circuit(s) as necessary.
Did you find and correct the condition? 

Go to Step 19 Go to Step 18
11 1. Turn OFF the ignition. 2. Disconnect the ECM harness connector.
3. Inspect for an intermittent and for a poor connection on the MIL control circuit at the
harness connector of the ECM (pin 42 of C-56
connector).
4. Repair the connection(s) as necessary.
Did you find and correct the condition? 

Go to Step 19 Go to Step 18
12 Repair the open circuit or high resistance on the voltage feed circuit of the MIL between the IPC (pin
8 of B-24 connector) and Meter (15A) fuse (C-14).
Did you complete the repair? 

Go to Step 19 
13 Repair the open circuit or high resistance on the
control circuit of the MIL between the ECM (pin 42 of
C-56 connector) and the IPC (pin 17 of B-24
connector).
Did you complete the repair? 

Go to Step 19 
14 1. Turn OFF the ignition.
2. Inspect for an intermittent and for poor connections on the MIL circuits at the IPC (pins
17 and 8 of B-24 connector).
3. Repair the connection(s) as necessary.
Did you find and correct the condition? 

Go to Step 19 Go to Step 16
15 Replace the MIL bulb. Did you complete the replacement? 

Go to Step 19 
16 Repair or replace the IPC (meter assembly).
Did you complete the repair or replacement? 

Go to Step 19 

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ISUZU KB P190 2007

Engine Control System (4JH1) 6E-237
DTC P1690 (Symptom Code 8) (Flash Code 77)
Circuit Description
The malfunction indicator lamp (MIL) is located on the
instrument panel cluster (IPC). The battery voltage is
supplied to the MIL. The engine control module (ECM)
turns the MIL ON by grounding the MIL control circuit.
After a fixed time passes, the ECM turns OFF the MIL
with the ignition ON and the engine OFF. The MIL has
the following functions:
• The MIL informs the driver that a malfunction has
occurred and the vehicle should be taken in fo
r
service as soon as possible.
• The MIL illuminates during a bulb test and a
system test.
•
A DTC will be stored if a MIL is requested by the
ECM.
If the ECM detects a short to battery or ignition voltage
on the MIL control circuit, this DTC will set.
Condition for Running the DTC • The ignition switch is ON.
Condition for Setting the DTC
• The ECM detects a high voltage condition on the
MIL control circuit for longer than 1 second when
the MIL is commanded ON.

Action Taken When the DTC Sets
• The ECM does not illuminates the MIL when the
diagnostic runs and fails.
Condition for Clearing the DTC
• 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.
Test Description
The number below refers to the step number on the
diagnostic table.
3. If the control circuit of the MIL between the ECM and
the IPC is normal, the control circuit voltage low DTC
P1690 (Symptom Code 4) will set.
4. If the control circuit of the MIL between the ECM and
the IPC is normal, the control circuit voltage low DTC
P1690 (Symptom Code 4) will set.

DTC P1690 (Symptom Code 8) (Flash Code 77)
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. Perform the Malfunction Indicator Lamp (MIL) test with the scan tool.
4. Command the MIL ON with the scan tool.
Does the MIL turn ON when commanded ON with
the scan tool? 

Go to Diagnostic Aids Go to Step 3
3 1. Turn OFF the ignition. 2. Remove the instrument panel cluster (IPC) in order to disconnect the IPC harness B-23
connector.
3. Disconnect the IPC harness B-23 connector.
4. Turn ON the ignition, with the engine OFF.
5. Monitor the Diagnostic Trouble Code (DTC) Information with the scan tool.
Does DTC P1690 (Symptom Code 4) set, but not
DTC P1690 (Symptom Code 8)? 

Go to Step 5 Go to Step 4
4 1. Test the control circuit of the MIL between the engine control module (ECM) (pin 42 of C-56
connector) and the IPC (pin 17 of B-23
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

6E-240 Engine Control System (4JH1)
Step Action Value(s) Yes No
5 1. Turn OFF the ignition.
2. Replace the glow relay with the starter relay or replace with a known good relay.
3. Turn ON the ignition, with the engine OFF.
4. Connect a test lamp between the metal bus bar (glow plug power supply E-49 connector) and a
known good ground.
5. Perform the Glow Relay test with the scan tool.
6. Command the Glow Relay ON with the scan tool while observing the test lamp.
Does the test lamp turn ON only when commanded
ON with the scan tool? 

Go to Step 9 Go to Step 6
6 Inspect the Glow (60A) slow blow fuse (SBF-8) in the engine room fuse block.
Is the Glow (60A) slow blow fuse (SBF-8) open? 

Go to Step 10 Go to Step 7
7 1. Turn OFF the ignition. 2. Remove the glow relay in the engine room relay block.
3. Connect a test lamp between the voltage feed circuit of the glow relay terminal (pin 4 of X-5
connector) and a known good ground.
4. Turn ON the ignition, with the engine OFF.
Does the test lamp illuminate? 

Go to Step 8 Go to Step 11
8 1. Turn ON the ignition, with the engine OFF. 2. Connect a test lamp between the power supply circuit of glow plugs (pin 1 of X-5 connector) and
a known good ground.
Does the test lamp illuminate? 

Go to Step 13 Go to Step 12
9 1. Turn OFF the ignition. 2. Inspect for an intermittent and for poor connections at the glow relay terminals (pins 1
and 4 of X-5 connector).
3. Repair the connection(s) as necessary.
Did you find and correct the condition? 

Go to Step 16 Go to Step 14
10 1. Replace the Glow (60A) slow blow fuse (SBF-8). If the slow blow fuse continues to open, repair
the short to ground on a circuit fed by the slow
blow fuse or check for a shorted attached
component.
2. Repair the short to ground or replace the component as necessary.
Did you complete the repair? 

Go to Step 16 
11 Repair the open circuit in the battery voltage supply
circuit between the Glow (60A) slow blow fuse (SBF-
8) and the glow relay (pin 1 of X-5 connector).
Did you complete the repair? 

Go to Step 16 
12 Repair the open circuit in the switched battery
voltage supply circuit between the glow relay (pin 1
of X-5 connector) and the glow plugs (E-49
terminal).
Did you complete the repair? 

Go to Step 16 

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ISUZU KB P190 2007

Engine Control System (4JH1) 6E-241
Step Action Value(s) Yes No
13 Important: The glow plugs may be burnt out if the
battery voltage supply circuit is shorted to a voltage
source.
Repair the short to battery or ignition voltage on the
switched battery voltage supply circuit between the
glow relay (pin 1 of X-5 connector) and the glow
plugs (E-49 terminal).
Did you complete the repair? 

Go to Step 16 
14 Replace the glow relay.
Did you complete the replacement? 

Go to Step 16 
15 Replace the appropriate glow plug.
Did you complete the replacement? 

Go to Step 16 
16 1. Reconnect all previously disconnected
components, relay, fuse or harness connector(s).
2. Turn OFF the ignition for 30 seconds.
3. Turn ON the ignition, with the engine OFF.
4. Connect a test lamp between the metal bus bar (glow plug power supply E-49 connector) and a
known good ground.
5. Perform the Glow Relay test with the scan tool.
6. Command the Glow Relay ON with the scan tool while observing the test lamp.
Does the test lamp turn ON only when commanded
ON with the scan tool? 

Go to Step 4 Go to Step 2


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ISUZU KB P190 2007

Engine Control System (4JH1) 6E-243
Step Action Value(s) Yes No
7 1. Turn OFF the blower motor switch.
2. Turn ON the A/C switch.
Does the A/C compressor clutch keep OFF
(disengage)? 

Go to Step 8 Go to Chart 2 of 2
with heater Step 8 OR
Go to Chart 2 of 2
without heater Step 10
8 1. Turn ON the blower motor switch. 2. Keep the A/C switch ON.
Does the A/C compressor clutch ON and OFF
(engage and disengage) periodically within the
Condition for Running the A/C Compressor? 

Go to Step 9 Go to Step 10
9 Does the air flow cool enough. 
System OK Refer to Applicable
Diagnostic Chart in Heating & Air Conditioning Section
10 Does the A/C Relay Command parameter indicate ON at previous step?

Go to Step 14 Go to Chart 2 of 2
with heater Step 9 OR
Go to Chart 2 of 2
without heater Step 11
11 1. Turn OFF the ignition. 2. Disconnect the A/C compressor clutch harness connector (E-3).
3. Start the engine.
Does the A/C compressor clutch ON (engage)? 

Go to Step 22 Go to Step 12
12 1. Turn OFF the ignition. 2. Remove the A/C compressor relay from the engine room relay block.
3. Connect a test lamp between the A/C compressor clutch voltage supply circuit (pin 2 of
X-14 connector) and a known good ground.
4. Turn ON the ignition, with the engine OFF.
Does the test lamp illuminate? 

Go to Step 13 Go to Step 21
13 Repair the short to battery or ignition voltage on the A/C compressor voltage feed circuit between the
A/C compressor relay (pin 2 of X-14 connector) and
the A/C compressor (E-3).
Did you complete the repair? 

Go to Step 23 
14 1. Turn OFF the ignition.
2. Remove the A/C compressor relay from the engine room fuel block.
3. Connect a test lamp between the voltage feed circuit of the relay switch side terminal (pin 1 of
X-14 connector) and known good ground.
4. Turn ON the ignition, with the engine OFF.
Does the test lamp illuminate? 

Go to Step 15 Go to Step 17
15 1. Keep the ignition ON, with the engine OFF. 2. Disconnect the test lamp.
3. Connect a 3-amp fused jumper wire between both switch side terminals of the A/C compressor
relay (pins 1 and 2 of X-14 connector).
Does the A/C compressor clutch click (engage)? 

Go to Step 19 Go to Step 16

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ISUZU KB P190 2007

6E-244 Engine Control System (4JH1)
Step Action Value(s) Yes No
16 1. Keep the ignition ON, with the engine OFF.
2. Keep 3-amp fused jumper wire with connected.
3. Disconnect A/C compressor clutch harness connector.
4. Connect a test lamp between A/C compressor voltage feed circuit (E-3) and a known good
ground.
Does the test lamp illuminate? 

Go to Step 20 Go to Step 18
17 Repair the open circuit or high resistance on the relay switch side voltage feed circuit between the
A/C compressor relay (pin 1 of X-14 connector) and
the A/C (10A) fuse (EB-13).
Did you complete the repair? 

Go to Step 23 
18 Repair the open circuit or high resistance on the
relay switched voltage supply circuit between the
A/C compressor relay (pin 2 of X-14 connector) and
the A/C compressor clutch (pin 1 of E-3 connector).
Did you complete the repair? 

Go to Step 23 
19 1. Turn OFF the ignition.
2. Inspect for an intermittent and for poor connections at the A/C compressor relay
terminals (pins 3 and 5 of X-14 connector).
3. Repair the connection(s) as necessary.
Did you find and correct the condition? 

Go to Step 23 Go to Step 21
20 1. Turn OFF the ignition. 2. Inspect for an intermittent and for a poor connection at the harness connector of the A/C
compressor clutch (E-3).
3. Repair the connection(s) as necessary.
Did you find and correct the condition? 

Go to Step 23 Go to Step 22
21 Replace the A/C compressor relay. Did you complete the replacement? 

Go to Step 23 
22 Replace the A/C compressor. Refer to Heating and
Air Conditioning section.
Did you complete the replacement? 

Go to Step 23 
23 1. Reconnect all previously disconnected fuse,
relay or harness connector(s).
2. Turn OFF the ignition for 30 seconds.
3. Turn ON the ignition, with the engine OFF.
4. Turn ON the blower motor switch.
Does the blower motor turn ON and operate
correctly? 

Go to Step 4 Refer to Applicable
Diagnostic Chart in Heating & Air Conditioning Section

Chart 2 of 2 with heater
Step Action Value(s) Yes No
1 1. Turn OFF the ignition.
2. Replace the thermo relay with the horn relay or replace with a known good relay.
3. Turn OFF the blower motor switch.
4. Turn OFF the A/C switch.
5. Turn ON the ignition, with the engine OFF.
Does the A/C Request Signal parameter indicate
OFF? 

Go to Step 33 Go to Step 2

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ISUZU KB P190 2007