DTC P0325, P0327, or P0328 (LDD)
Diagnostic Instructions
DTC Descriptors
| 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 s. |
| • |
This DTC runs continuously
within the enabling conditions. |
| • |
DTCs 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 s.
P0327 00
The ECM detects the knock sensor signal circuit is shorted to
ground for greater than 5 s.
P0328 00
The ECM detects the knock sensor signal circuit is shorted to
voltage for greater than 5 s.
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
| 1. |
Engine running, observe the
DTC information with a scan tool. DTC P0325 00, P0327 00, or P0328
00 should not set. |
| 2. |
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
| 1. |
Ignition OFF, disconnect the
harness connector at the B68 Knock Sensor. |
| 2. |
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. |
| 3. |
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. |
| 4. |
If all circuits test normal,
test or replace the B68 Knock Sensor. |
Repair Instructions
Perform the
Diagnostic Repair Verification after completing the diagnostic
procedure.
|
