Every now & then I get P0327 code “Knock Sensor (KS) Circuit Front –B”, usually while the car is still not completely warmed up.
It doesn’t cause any trouble, but I would like to know what it is and hopefully how to fix it.

Anybody know?
Thanks.



[Modified by EuG, 11:02 AM 11/1/2002]

 

Here's a brief answer................

Document ID # 554279
2000 Chevrolet/Geo Corvette

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DTC P0327 Knock Sensor (KS) 1 Circuit




Circuit Description
The knock sensor (KS) system detects engine detonation. The PCM retards the spark timing based on the signals from the knock sensors. The knock sensors produce an AC voltage. The knock sensor voltages are an input to the PCM. The amount of AC voltage produced is proportional to the amount of knock.

An operating engine produces a normal amount of engine mechanical vibration (noise). The knock sensors produce an AC voltage signal from this noise. When an engine operates, the PCM learns the minimum and maximum frequency of the noise the engine produces. When the PCM determines that this frequency is less than or greater than the expected amount, a knock sensor DTC sets.

Conditions for Running the DTC
The engine speed is between 1650 RPM and 3000 RPM.
The MAP is less than 49 kPa (7.1 psi).
The engine coolant temperature is greater than 60°C (140°F).
The throttle angle is greater than the idle throttle angle.
The engine has been operating for longer than 20 seconds.
Conditions for Setting the DTC
The PCM determines that this frequency is less than or greater than the expected amount for less than 3.0 seconds.

Action Taken When the DTC Sets
The PCM illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
The PCM records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the PCM stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the PCM records the operating conditions at the time of the failure. The PCM writes the conditions to the Freeze Frame and updates the Failure Records.
Conditions for Clearing the MIL/DTC
The PCM turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
A last test failed, or current DTC, clears when the diagnostic runs and does not fail.
A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
Use a scan tool in order to clear the MIL and the DTC.
Diagnostic Aids

Important
Remove any debris from the PCM\TAC module connector surfaces before servicing the PCM\TAC module. Inspect the PCM\TAC module connector gaskets when diagnosing/replacing the modules. Ensure that the gaskets are installed correctly. The gaskets prevent contaminate intrusion into the PCM\TAC modules.
For any test that requires probing the PCM or a component harness connector, use the Connector Test Adapter Kit J 35616-A . Using this kit prevents damage to the harness/component terminals. Refer to Using Connector Test Adapters in Wiring Systems.

Inspect the knock sensor for proper installation. A knock sensor that is loose or over torqued may cause DTC P0327 to set.
The knock sensor jumper harness is located at the left rear of the intake manifold near the crankcase vent.
For an intermittent, refer to Symptoms .
Test Description
The numbers below refer to the step numbers on the diagnostic table.

This verifies the malfunction is present. The scan tool will display DTC Ran=Yes and Pass=Int if the failure is intermittent. This indicates the diagnostic passed this ignition cycle and failed this ignition cycle. At this point the resistance of the knock sensors should be verified to be in the correct range. If the knock sensor resistances are correct, inspect the KS system wiring connections. When inspecting the KS system connections, start at the KS system jumper harness connector located behind the intake manifold. Then inspect the connections at the PCM. Refer to the wiring schematic for the correct connector and terminal. Then inspect the connections at the appropriate knock sensor. Failure Records data does not include the parameter KS Activity, however other parameters may aid in locating the conditions under which an intermittent occurred.

This test isolates the Knock Sensor from the rest of the circuit.

Tap on the engine block in the location of the appropriate knock sensor.

Step
Action
Values
Yes
No

1
Did you perform the Powertrain On-Board Diagnostic (OBD) System Check?
--
Go to Step 2
Go to Powertrain On Board Diagnostic (OBD) System Check

2

Important
If an engine knock can be heard, repair the engine mechanical condition before proceeding with this diagnostic.


Turn ON the ignition with the engine OFF.
Review the Freeze Frame and/or Failure Records data for this DTC and observe the parameters.
Turn OFF the ignition for 15 seconds.
Start the engine.
Operate the vehicle within the conditions required for this diagnostic to run, and as close to the conditions recorded in Freeze Frame and/or Failure Records as possible. Special operating conditions that you need to meet before the PCM will run this diagnostic, where applicable, are listed in Conditions for Running the DTC.
Select the Diagnostic Trouble Code (DTC) option and the Specific DTC option, then enter the DTC number with the scan tool.
Does the scan tool indicate that this diagnostic failed this ignition?
--
Go to Step 3
Go to Diagnostic Aids

3
Disconnect the knock sensor electrical connector located behind the intake manifold.
Measure the resistance of the appropriate knock sensor by connecting the DMM between the knock sensor signal circuit on the sensor side and the engine block with the DMM .
Set the DMM to the 400K ohm scale.
Is the resistance of the knock sensor within the specified range?
93-107Kohms
Go to Step 4
Go to Step 6

4
Connect the DMM between the appropriate knock sensor signal circuit on the sensor side and the engine block.
Set the DMM to the AC voltage scale.

Important
Do not tap on plastic engine components.


Tap on the engine in the area of the appropriate knock sensor while observing the signal indicated on the DMM .
Is any signal indicated on the DMM while tapping on the engine near the Knock Sensor?
--
Go to Step 5
Go to Step 7

5
Disconnect the PCM connector C1 located on the same side as the manufacturer's logo. Refer to Powertrain Control Module (PCM) Replacement .
Test the KS signal circuit between the PCM and the knock sensor connector for the following:
An open
A short to voltage
A short to ground
If you find a circuit condition, repair as necessary. Refer to Wiring Repairs in Wiring Systems.
Did you find and correct the condition?
--
Go to Step 10
Go to Step 8

6
Remove the intake manifold. Refer to Intake Manifold Replacement in Engine Mechanical 5.7L.
Test for an open or a short to ground in the signal circuit between the knock sensor jumper harness connector, located at the back of the intake manifold, and the knock sensor connector. Refer to Testing for Continuity or Testing for Short to Ground in Wiring Systems.
If a condition is located repair the circuit as necessary. Refer to Wiring Repairs in Wiring Systems.
Did you find and correct the condition?
--
Go to Step 10
Go to Step 7

7
Replace the Knock Sensor. Refer to Knock Sensor (KS) Replacement .

Is the action complete?
--
Go to Step 10
--

8
Inspect the KS signal circuit for a poor connection at the PCM. Refer to Testing for Intermittent and Poor Connections in Wiring Systems.
If you find a poor connection repair the terminal as necessary. Refer to Repairing Connector Terminals in Wiring Systems.
Did you find and correct the condition?
--
Go to Step 10
Go to Step 9

9

Important
Program the replacement PCM.


Replace the PCM. Refer to Powertrain Control Module (PCM) Replacement .

Is the action complete?
--
Go to Step 10
--

10
Select the Diagnostic Trouble Code (DTC) option and the Clear DTC Information option with the scan tool.
Start the engine and idle at the normal operating temperature.
Select the Diagnostic Trouble Code (DTC) option and the Specific DTC option, then enter the DTC number with the scan tool.
Operate the vehicle within the conditions for running this DTC as specified in the supporting text, if applicable.
Does the scan tool indicate that this test ran and passed?
--
Go to Step 11
Go to Step 2

11
Select the Capture Info option and the Review Info option with the scan tool.

Does the scan tool display any DTCs that you have not diagnosed?
--
Go to the applicable DTC table
System OK


© Copyright General Motors Corporation. All Rights Reserved.


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Document ID # 554279
2000 Chevrolet/Geo Corvette

 

Tom, you rule man!!!!

Thanks a BUNCH for this awesome info!!!!

 

Where can I get this Documentation for all codes, is there a GM manual that you have purchased, or some documentation that I can download????

I have a few codes that I would like to lookup myself.....thanks for any help you can offer