Isuzu KB P190. Manual - part 566

6E–94

ENGINE DRIVEABILITY AND EMISSIONS

NO CHECK ENGINE LAMP (MIL)

Circuit Description

The check engine lamp should be illuminated and
steady for about five seconds with the ignition “ON” and
the engine stopped.  Ignition feed voltage is supplied to
the check engine lamp bulb through the meter fuse.
The Engine Control Module (ECM) turns the check
engine lamp “ON” by grounding the check engine lamp
driver circuit.

Diagnostic Aids

An intermittent check engine lamp may be cased by a
poor connection, rubbed-through wire insulation, or a

wire broken inside the insulation.  Check for the
following items:

• Inspect the ECM harness and connections for

improper mating, broken locks, improperly formed or
damaged terminals, poor terminal-to-wire connection,
and damaged harness.

• If the engine runs OK, check for a faulty light bulb, an

open in the check engine lamp driver circuit, or an
open in the instrument cluster ignition feed.

• If the engine cranks but will not run, check for an

open ECM ignition or battery feed, or a poor ECM to
engine ground.

No Check Engine Lamp (MIL)

Step

Action

Value(s)

Yes

No

1

Check the “Meter” fuse (15A). 
If the fuse is burnt out, repair as necessary. 
Was the problem found?

—

Verify repair

Go to Step 2

ENGINE DRIVEABILITY AND EMISSIONS

6E–95

2

Using the DVM and check the “CHECK ENGINE”
lamp circuit.

1. Ignition “Off”, engine “Off”. 

2. Disconnect the ECM connector. 

3. Ignition “On”. 

4. Check the circuit for open circuit. 

Was the DVM indicated specified value?

10 - 14.5V

Go to Step 5

Go to Step 3

3

Check the “CHECK ENGINE” lamp bulb. 
If the bulb is burnt out, repair as necessary. 
Was the problem found?

—

Verify repair

Go to Step 4

4

Using the DVM and check the “CHECK ENGINE”
lamp circuit.

1. Ignition “Off”, engine “Off”. 

2. Disconnect the meter connector and ECM

connector. 

3. Check the circuit for open circuit. 

Was the problem found?

—

Verify repair

Go to Step 5

5

Is the ECM programmed with the latest software
release? 
If not, download the latest software to the ECM using
the “SPS (Service Programming System)”. 
Was the problem solved?

—

Verify repair

Go to Step 6

6

Replace the ECM. 
Is the action complete? 
IMPORTANT:  The replacement ECM must be
programmed. Refer to section of the Service
Programming System (SPS) in this manual. 
Following ECM programming, the immobilizer system
(if equipped) must be linked to the ECM. Refer to
section 11 “Immobilizer System-ECM replacement” for
the ECM/Immobilizer linking procedure.

—

Verify repair

—

Step

Action

Value(s)

Yes

No

V

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C56(J2)

32

17

C56(J2)

B24

6E–96

ENGINE DRIVEABILITY AND EMISSIONS

CHECK ENGINE LAMP (MIL) “ON” STEADY

Circuit description

The check engine lamp should always be illuminated
and steady for about five seconds with ignition “ON” and
the engine stopped.  Ignition feed voltage is supplied
directly to the check engine lamp indicator.  The Engine
Control Module (ECM) turns the check engine lamp
“ON” by grounding the check engine lamp driver circuit.
The check engine lamp should not remain “ON” with the
engine running and no DTC(s) set.  A steady check
engine lamp with the engine running and no DTC(s)
suggests a short to ground in the check engine lamp
driver circuit.

Diagnostic Aids

An intermittent may be caused by a poor connection,
rubbed-through wire insulation, or a wire broken inside
the insulation.  Check for the following items:

• Poor connection or damaged harness - Inspect the

ECM harness and connectors for improper mating,
broken locks, improperly formed or damaged
terminals, poor terminal-to-wire connection, and
damaged harness.

Check Engine Lamp (MIL) “ON” Steady

Step

Action

Value(s)

Yes

No

1

1. Ignition “Off”, engine “Off”. 

2. Disconnect the ECM connector. 

3. Ignition “On”. 

Was the “CHECK ENGINE” lamp turned on?

—

Go to Step 2

Go to Step 4

ENGINE DRIVEABILITY AND EMISSIONS

6E–97

2

Using the DVM and check the “CHECK ENGINE”
lamp circuit.

1. Ignition “Off”, engine “Off”. 

2. Disconnect the meter connector and ECM

connector. 

3. Check the circuit for short to ground circuit. 

Was the problem found?

—

Verify repair

Go to Step 3

3

Replace the meter assembly. 
Is the action complete?

—

Verify repair

—

4

Is the ECM programmed with the latest software
release? 
If not, download the latest software to the ECM using
the “SPS (Service Programming System)”. 
Was the problem solved?

—

Verify repair

Go to Step 5

5

Replace the ECM. 
Is the action complete? 
IMPORTANT:  The replacement ECM must be
programmed. Refer to section of the Service
Programming System (SPS) in this manual. 
Following ECM programming, the immobilizer system
(if equipped) must be linked to the ECM. Refer to
section 11 “Immobilizer System-ECM replacement” for
the ECM/Immobilizer linking procedure.

—

Verify repair

—

Step

Action

Value(s)

Yes

No

32

C56(J2)