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Isuzu engine C22NE / 22LE / 20LE. Service manual - part 91

DRIVEABILITY AND EMISSIONS 6E1-193

DTC (Flash DTC = 17)

Injector Circuit Malfunction (Cont'd)

Step

Action

Value(s)

Yes

Does the engine Idle Condition change?

Note the detected faulty injector.

Go to Step 6

Go to Step 8

1. Ignition off.

2. Disconnect the ECM connector for the affected

injectors.

3. With a test light (commercial available) connected to

B+, probe the affected applicable injector circuit.

Does the test light illuminate?

Go to Step 7

Go to Step 8

Repair short to ground in the injector driver circuit.

Is the action complete?

Verify Repair

Re-connect the ECM connector.

1. Disconnect the injector test connector.

2. Ignition ON.

3. Use a test light (commercial available)

connected to ground to probe the injector connector

terminal.

4. Only the Ign+ terminal should illuminate the test high.

Besides the Ign+, did any other terminal illuminate the test

light?

Go to Step 9

Go to Step 10

Repair the short to voltage in the injector driver circuit.

Verify Repair

Go to Step 10

1. Ignition OFF.

2. Disconnect the ECM connector.

3. Clip one lead of an ohmmeter to the ignition pin on the

harness side ECM connector.

4. Touch the other lead to the another pin in that

connector.

Instead of normal injector resistance, did the ohmmeter

indicate an open circuit?

Go to Step 11

Go to Step 12

Repair the open circuit or open injector.

Verify Repair

Go to Step 12

Replace the *EPROM or ECM.

Note) *Refer to 6E1-243.

Verify repair

6E1-194 DRIVEABILITY AND EMISSIONS

DRIVEABILITY AND EMISSIONS 6E1-195

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 = 41)

IGNITION COIL DRIVER "B" 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 coil driver

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 B/coil driver B line. When the

ECM detects a problem in the ignition control circuit, it

will set DTC 41.

Conditions for Setting the DTC

• Fault feedback line generates an interrupt on start

of dwell.

• No Electronic Spark Timing actiration 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.

6E1-196 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 41

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 B/Coil Driver B (#2, #3 cyl.)

line.

DTC (Flash DTC = 41)

Ignition Coil Driver "B" 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 8

Replace the EPROM or ECM.

Is the repair complete?

Note) Refer to 6E1-243.

Verify repair

Content .. 89 90 91 92 ..