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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