Isuzu KB P190. Manual — part 317

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 for
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

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



6E-236 Engine Control System (4JH1)

Step Action

Value(s)

Yes

No

17

1. Turn OFF the ignition for 30 seconds.
2. Turn ON the ignition for 10 seconds, with the

engine OFF.

3. Monitor the Diagnostic Trouble Code (DTC)

Information with the scan tool.

Does the DTC fail this ignition?



Go to Step 18

Go to Diagnostic

Aids

18

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 19



19

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 2

Go to Step 20

20

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-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 for
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