Isuzu engine C22NE / 22LE / 20LE. Manual - part 83

 

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Isuzu engine C22NE / 22LE / 20LE. Manual - part 83

 

 

DRIVEABILITY AND EMISSIONS  6E1-161

DIAGNOSTIC TROUBLE CODE (DTC) (Flash DTC = 16)

KNOCK SENSOR (KS) DISCONNECTED MALFUNCTION

Circuit Description

The knock sensor (KS) system is used to detect

engine detonation. The knock sensor produced an AC

voltage signal. The knock sensor sends this signal to

the ECM. The amplitude and the frequency of the AC

voltage signal depends upon the knock level being

detected. The ECM will then retard the spark timing

based on the signals from the Knock Sensor.

This code detects a disconnected knock sensor. Then

a DTC 16 will set.

Conditions for Setting the DTC

• Electronic and spark control enabled.
• Engine running.
• ECM powered up.
• Engine speed is greater than 2400rpm.
All the above mentioned conditions are met.

Action Taken When the DTC Sets

• The Malfunction Indicator Lamp (MIL) will illuminate

the fault is detected.

• The ECM will use a calculated spark retard value in

order to minimize the knock during the conditions

when the knock is likely to occur. The calculated

value will vary based on the engine speed and load.

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

Correct any abnormal engine noise before using the

diagnostic table.

Check for an open ignition feed circuit.

Test Description

Number(s) below refer to the step number(s) on the

Diagnostic Table.

2. If the conditions for the test as described above are

met, a Diagnostic Trouble Code 16 will set and MIL

will illuminate.

4. If the engine has an internal knock or audible noise

that causes a knocking type noise on the engine

6E1-162  DRIVEABILITY AND EMISSIONS

block, the knock sensor may be responding to the

noise.

6. Any circuitry, that is suspected as causing the

complaint, should be thoroughly checked for

backed out terminals, improper mating, broken

locks, improperly formed or damaged terminals,

poor terminal to wiring connections or physical

damage to the wiring harness.

8. Checking the internal resistance of the knock

sensor verifies if the knock sensor or the wiring to

the knock sensor is OK.

DTC (Flash DTC = 16)

KS Sensor Disconnected Malfunction

Step

Action

Value(s)

Yes

No

1

Was the Powertrain On-Board Diagnostic (OBD) System

Check performed?

-

Go to Step 2

Go to

Powertrain

OBD System

Check

2

1.  Start the engine.

2.  Install a Scan Tool.

3.  Clear the Diagnostic Trouble Codes.

4.  Run the engine at slightly more than 10% throttle angle.

Does the Malfunction Indicator Lamp (MIL) illuminate?

-

Go to Step 4

Go to Step 3

3

1.  Turn the ignition Switch ON, with engine OFF.

Does the Malfunction Indicator Lamp (MIL) illuminate?

-

Go to Step 4

Go to Step 12

4

Listen to the engine while raising and lowering the engine

speed.

Is a knock or audible noise present?

-

Go to Step 5

Go to Step 6

5

Repair the mechanical engine problem or a loose bracket

or component.

Is the action complete?

-

Go to Step 12

-

6

Check for a poor connection at the ECM connector,

Knock sensor signal circuit and repair as necessary.

Was a repair necessary?

-

Go to Step 12

Go to Step 7

7

Replace the EPROM or ECM.

Is the action complete?

Note) Refer to 6E1-243.

-

Go to Step 12

-

8

1.  Turn the ignition switch OFF.

2.  Disconnect the ECM connectors at the ECM.

3.  With a Digital Voltmeter (DVM) connected to ground,

measure the resistance of the knock sensor through

the knock sensor signal circuit.

Is the measured value within the specified value?

95K-105K

OHMS

Go to Step 6

Go to Step 9

9

Check the knock sensor electrical connector for a poor

connection and repair as necessary.

Was a repair necessary?

-

Go to Step 12

Go to Step 10

10

Check the knock sensor signal circuit for an open or a

short to ground or to voltage and repair as necessary.

Was a repair necessary?

-

Go to Step 12

Go to Step 11

11

Replace the Knock Sensor(KS).

Is the action complete?

-

Go to Step 12

-

DRIVEABILITY AND EMISSIONS  6E1-163

DTC (Flash DTC = 16)

KS Sensor Disconnected Malfunction (Cont'd)

Step

Action

Value(s)

Yes

No

12

1.  Using the Scan Tool, clear the Diagnostic Trouble

Codes.

2.  Start the engine and idle at normal operating

temperature.

3.  Operate the vehicle within the conditions for setting this

Diagnostic Trouble Code as specified in the supporting

text.

Does the Scan Tool indicate that this diagnostic has ran

and passed?

-

Go to Step 13

Go to Step 2

13

Check is any additional Diagnostic Trouble Codes are set.

Are any Diagnostic Trouble Codes displayed that have not

been diagnosed?

-

Go to

applicable

Diagnostic

Trouble Code

table

System OK

6E1-164  DRIVEABILITY AND EMISSIONS

 

 

 

 

 

 

 

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