P0325

Diagnostic Chart:

Wiring Diagram:

CIRCUIT DESCRIPTION

The VCM uses the Knock Sensors in order to detect engine detonation. This detection allows the VCM to retard the Ignition Control (IC) spark timing based on the KS signal the VCM receives. The circuitry within the knock sensor pulls down the VCM-supplied 5 volt signal, so that under a no knock condition the signal on the KS circuit measures about 1.3 volts. The knock sensors produce an IAC signal that rides on the 1.3 volts DC. The signal amplitude and frequency are dependent upon the amount of the knock being experienced.

The VCM contains a replaceable Knock Sensor (KS) module. The KS module contains the circuitry that allows the VCM to utilize the KS signal and to diagnose the KS sensors and circuitry. If the KS module is missing or faulty which causes a continuous knock condition, the VCM sets this DTC.

CONDITIONS FOR SETTING THE DTC

^ The DTC P0327 is not active.

^ Engine run time is at least 120 seconds.

^ System voltage is greater than 10 volts but is no more than 17.1 volts.

^ The VCM detects a problem with the KS module circuitry that causes the knock to be indicated continuously.

^ The above conditions met for up to 0.5 second.

ACTION TAKEN WHEN DTC SETS

^ The VCM will not illuminate the MIL

^ The VCM will store the conditions which were present when the DTC set as a Fail Records data only. This information will not store as Freeze Frame Data.

^ The VCM will use a calculated spark retard value in order to minimize the knock during the conditions when the knock is most likely to occur. The calculated value will vary based on the engine speed and load

CONDITIONS FOR CLEARING THE MIL/DTC

^ The VCM turns the MIL OFF after 3 consecutive drive trips when the test has Run and Passed and not Failed.

^ A history DTC will clear it no fault conditions have been detected for 40 warm-up cycles (coolant temperature has risen 22°C (40°F) from the startup coolant temperature and the engine coolant temperature exceeds 70°C (160°F) during the same ignition cycle).

^ Use the scan tool Clear Information function.

^ Disconnect the VCM battery feed for 30 seconds.

DIAGNOSTIC AIDS

Check for the following conditions:

^ A poor connection at the VCM. Inspect the KS module connector for the following conditions:

- Backed out terminals

- Broken locks

- Improperly formed or damaged terminals

^ A damaged or improperly installed KS module. Check for the following items:

- Bent pins

- Deformed terminals

- KS module not completely seated

^ Improper Knock Sensor torque specification. Torque the Knock sensor to 19 N.m (14 lb ft). Refer to Fastener Notice.

Review the Fail Records vehicle mileage since the diagnostic test last failed in order to help determine how often the conditions that caused the DTC to set occur. This may assist in diagnosing the condition.

TEST DESCRIPTION

The numbers below refer to the step numbers on the diagnostic table.

2. This step ensures that the fault is present.

5. This step checks for an improperly installed KS module.