Content .. 90 91 92 93 ..

Isuzu engine C22NE / 22LE / 20LE. Manual - part 92

DRIVEABILITY AND EMISSIONS 6E1-197

HOT IN START AND RUN

IG.

Coil

Fuse

15A

I/P

FUSE

BLOCK

W/G

Ignition

Coil

Ignition

Coil

1.25

Engine

Control

Module

(ECM)

Electronic Spark

Timing Control

1.25

BLK

1.25

BLK

1,4

2,3

DIAGNOSTIC TROUBLE CODE (DTC) (Flash DTC = 42)

IGNITION COIL DRIVER "A" SHORT TO BATTERY

Circuit Description

The ignition control circuit in ECM provides a zero volt

or a 5 volt signal to the ignition coil driver. The normal

circuit voltage is zero volts. When the module receives

the 5 volt signal from the ignition control circuit, it

provides a ground path for the B+ voltage supplied to

the ignition primary coil. When the ECM turns off the 5

volts to the module, the module will remove the

ground path of the ignition primary coils; causing the

magnetic field produces a voltage in the secondary

coils which fires the spark plug.

The circuit between the coil driver and the ignition

control circuit is monitored for a short to battery on the

Electronic Spark Timing A/coil driver A line. When the

ECM detects a problem in the ignition control circuit, it

will set DTC 42.

Conditions for Setting the DTC

• Fault feedback line generates an interrupt on start

of dwell.

• No Electronic Spark Timing requested by serial

data.

Action Taken When the DTC Sets

• The ECM will illuminate the malfunction indicator

lamp (MIL) the first time the fault is detected.

Conditions for Clearing the MIL/DTC

Once the ECM determines that a fault(s) has been

rectified then the CEL will switch OFF, although the

fault code will remain in the ECM memory.

Any fault codes will remain in ECM memory until -

1. They are cleared by disconnecting the Battery for

more than 30 seconds.

2. A service tool such as Tech 2 is used to clear them.

3. Ten consecutive starts without logging a fault.

Diagnostic Aids

Check for the following conditions:
• Poor connection at the ECM - Inspect the harness

connectors for backed-out terminals, improper

mating, broken locks, improperly formed or

6E1-198 DRIVEABILITY AND EMISSIONS

damaged terminals, and poor terminal-to-wire

connections.

• Damaged harness - Inspect the wiring harness for

damage; Open circuits, shorts to ground, or shorts

to Voltage. If the harness appears to be OK,

observe the Scan Tool display related to DTC 42

while moving the connector and wiring related to the

ignition system. A change in the display will indicate

the location of the fault.

• This code detects a short to battery on the

Electronic Spark Timing A/Coil Driver A (#1, #4 cyl.)

line.

DTC (Flash DTC = 42)

Ignition Coil Driver "A" Short To Battery

Step

Action

Value(s)

Yes

Was the "On-Board Diagnostic (OBD) System Check"

performed?

Go to Step 2

Go to OBD

System

Check

Check for a faulty connection or damaged terminals at the

ignition coil.

Was a problem found?

Verify repair

Go to Step 3

Check for a faulty connection or damaged terminals at the

ECM connector.

Was a problem found?

Verify repair

Go to Step 4

1. Ignition OFF.

2. Disconnect the ignition coil.

3. Check the ignition coil circuit for a short to battery.

Was a problem found?

Verify repair

Go to Step 5

Check for a short circuit between the ignition coil and the

ECM.

If a problem is found, repair the wire harness.

Is there still a problem?

Verify repair

Go to Step 6

Replace the ignition control module.

Verify repair.

Is there still a problem?

Go to Step 7

Replace the EPROM or ECM.

Is the repair complete?

Note) Refer to 6E1-243.

Verify repair

DRIVEABILITY AND EMISSIONS 6E1-199

HOT IN START AND RUN

IG.

Coil

Fuse

15A

I/P

FUSE

BLOCK

W/G

Ignition

Coil

Ignition

Coil

1.25

Engine

Control

Module

(ECM)

Electronic Spark

Timing Control

1.25

BLK

1.25

BLK

1,4

2,3

DIAGNOSTIC TROUBLE CODE (DTC) (Flash DTC = 63)

IGNITION COIL DRIVER "B" SHORT TO GROUND

Circuit Description

The ignition control circuit provides a zero volt or a 5

volt signal to the ignition coil driver. The normal circuit

voltage is zero volts. When the module receives the 5

volt signal from the engine control module (ECM), it

provides a ground path for the B+ voltage supplied to

the ignition primary coil. When the ECM turns off the 5

volts to the module, the module will remove the

ground path of the ignition primary coils; causing the

magnetic field produces a voltage in the secondary

coils which fires the spark plug.

The circuit between the ECM and the ignition control

module is monitored for a short to ground on the

Electronic Spark Timing B/coil driver B line. When the

ECM detects a problem in the ignition control circuit, it

will set DTC 63.

Conditions for Setting the DTC

• Fault feedback line generates an interrupt on end of

dwell.

• No Electronic Spark Timing activation reguested by

serial data.

Action Taken When the DTC Sets

• The ECM will illuminate the malfunction indicator

lamp (MIL) the first time the fault is detected.

Conditions for Clearing the MIL/DTC

Once the ECM determines that a fault(s) has been

rectified then the CEL will switch OFF, although the

fault code will remain in the ECM memory.

Any fault codes will remain in ECM memory until -

1. They are cleared by disconnecting the Battery for

more than 30 seconds.

2. A service tool such as Tech 2 is used to clear them.

3. Ten consecutive starts without logging a fault.

6E1-200 DRIVEABILITY AND EMISSIONS

Diagnostic Aids

Check for the following conditions:
• Poor connection at the ECM - Inspect the harness

connectors for backed-out terminals, improper

mating, broken locks, improperly formed or

damaged terminals, and poor terminal-to-wire

connections.

• Damaged harness - Inspect the wiring harness for

damage; Open circuits, shorts to ground, or shorts

to Voltage. If the harness appears to be OK,

observe the Scan Tool display related to DTC 63

while moving the connector and wiring related to the

ignition system. A change in the display will indicate

the location of the fault.

• This code detects a short to ground on the

Electronic Spark Timing B/coil Driver B(#2, #3 cyl.)

line.

DTC (Flash DTC = 63)

Ignition Coil Driver "B" Short To Ground

Step

Action

Value(s)

Yes

Was the "On-Board Diagnostic (OBD) System Check"

performed?

Go to Step 2

Go to OBD

System

Check

Check for a faulty connection or damaged terminals at the

ignition control module.

Was a problem found?

Verify repair

Go to Step 3

Check for a faulty connection or damaged terminals at the

ECM connector.

Was a problem found?

Verify repair

Go to Step 4

Check for an open circuit between the ignition coil and

ECM.

If a problem is found, repair the wire harness.

Is there still a problem?

Verify repair

Go to Step 5

Check for an short to ground between the ignition coil and

battery +.

If a problem is found, repair the wire harness.

Is there still a problem?

Verify repair

Go to Step 6

1. Ignition OFF.

2. Disconnect the ignition coil.

3. Check for an open circuit in the ignition coil.

Was a problem found?

Verify repair

Go to Step 5

Replace the ignition coil.

Verify repair.

Is there still a problem?

Go to Step 8

Replace the EPROM or ECM.

Is the repair complete?

Note) Refer to 6E1-243.

Verify repair

Content .. 90 91 92 93 ..