DTC P0325, P0327, or P0328 - LDE
Diagnostic Instructions
DTC Descriptor
DTC P0325 00: Knock Sensor Circuit
DTC P0327 00: Knock Sensor Circuit Low
Voltage
DTC P0328 00: Knock Sensor Circuit High
Voltage
Diagnostic Fault Information
Circuit
|
Short to Ground
|
Open/High Resistance
|
Short to Voltage
|
Signal Performance
|
Knock Sensor Signal
|
P0327 00
|
P0325 00
|
P0328 00
|
P0326 00
|
Low Reference
|
P0327 00
|
-
|
P0328 00
|
P0326 00
|
Circuit/System Description
The knock sensor system enables the engine control
module (ECM) to control the ignition timing for the best
possible performance while protecting the engine from potentially
damaging levels of detonation. The knock sensor produces an
alternating current (AC) voltage signal that varies depending
on the vibration level during engine operation. The ECM adjusts the
spark timing based on the amplitude and the frequency of the knock
sensor signal. The ECM receives the knock sensor signal through a
signal circuit and a low reference circuit. The ECM learns a
minimum knock sensor noise level at idle and uses calibrated values
for the rest of the RPM range. The ECM should monitor a normal
knock sensor signal within the noise channel.
Conditions for Running the DTC
P0325 00
This DTC runs continuously when
• |
The engine speed is greater than
700-2 500 RPM. |
• |
The airflow into the engine is greater than
40 mg/cylinder. |
• |
The engine run time is greater than
1 second. |
• |
This DTC runs continuously within the enabling
conditions. |
• |
DTC P0325 00 runs continuously once the
above conditions are met. |
P0327 00, P0328 00
• |
The engine speed is between
600-8 500 RPM. |
• |
DTCs P0327 00 and P0328 00 run
continuously once the above condition is met. |
Conditions for Setting the DTC
P0325 00
The ECM detects the knock sensor signal circuit is open for
greater than 5 seconds.
P0327 00
The ECM detects the knock sensor signal circuit is shorted to
ground for greater than 5 seconds.
P0328 00
The ECM detects the knock sensor signal circuit is shorted to
voltage for greater than 5 seconds.
Action Taken When the DTC Sets
DTCs P0325 00, P0327 00, and P0328 00 are
Type C DTCs.
Conditions for Clearing the DTC
DTCs P0325 00, P0327 00, and P0328 00 are
Type C DTCs.
Diagnostic Aids
• |
Inspect the knock sensor for physical damage and
proper installation. A knock sensor that is dropped or damaged may
cause a DTC to set. |
• |
Inspect the knock sensor for proper installation.
A knock sensor that is loose or over torqued may cause a DTC to
set. The knock sensor should be free of thread sealant. |
• |
The knock sensor mounting surface should be free
of burrs, casting flash, and foreign material. |
Reference Information
Schematic Reference
Engine Controls Schematics
Connector End View Reference
Component Connector End Views
Description and Operation
Knock Sensor System Description
Electrical Information Reference
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Verification
- Engine running, observe the DTC information with a
scan tool. DTC P0325 00, P0327 00, or P0328 00
should not set.
- Operate the vehicle within the conditions for running
the DTC to verify the DTC does not reset. You may also operate the
vehicle within the conditions that you observed from the freeze
frame/failure records data.
Circuit/System Testing
- Ignition OFF, disconnect the harness connector at the
B68 Knock Sensor.
- Ignition ON, test for 1-2 V between the low
reference circuit terminal 2 and ground.
⇒ |
If less than the specified range, test the circuit
for a short to ground or an open/high resistance. If the circuit
tests normal, replace the K20 Engine Control Module. |
⇒ |
If greater than the specified range, test the low
reference circuit for a short to voltage. If the circuit tests
normal, replace the K20 Engine Control Module. |
- Ignition ON, test for 2.5-3.5 V between the
signal circuit terminal 1 and ground.
⇒ |
If less than the specified range, test the signal
circuit for a short to ground or an open/high resistance. If the
circuit tests normal, replace the K20 Engine Control
Module. |
⇒ |
If greater than the specified range, test the
signal circuit for a short to voltage. If the circuit tests normal,
replace the K20 Engine Control Module. |
- If all circuits test normal, test or replace the
B68 Knock Sensor.
Repair Instructions
Perform the
Diagnostic Repair Verification after completing the diagnostic
procedure.
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