P0326

Diagnostic Chart:

Diagnostic Chart (cont'd):

Wiring Diagram:

CIRCUIT DESCRIPTION

The knock sensors are used to detect engine detonation, allowing the PCM to retard Ignition Control (IC) spark timing based on the Knock Sensor (KS) signal being received. The knock sensors produce an AC signal which rides on a 5 volts DC signal supplied by the PCM. The signal amplitude and frequency is dependent upon the amount of knock being experienced.

The PCM determines whether the knock sensors and related wiring are operating properly by monitoring the voltage level on the noise channel. The noise channel allows the PCM to diagnose the KS system by allowing the PCM to learn the amount of normal engine mechanical noise present. Normal engine noise varies depending on engine speed and load. When the PCM determines that an abnormally high noise channel voltage level is being experienced, a DTC P0326 will set.


CONDITIONS FOR SETTING THE DTC

- No active Throttle Position (TP) sensor, Vehicle Speed Sensor (VSS) or ECT sensor DTCs are set.

- The engine has been running for at least 10 seconds.

- The engine coolant temperature is greater than 65°C (149°F).

- Throttle angle is greater than 1.5%.

- Engine speed is between 2500 RPM and 2900 RPM.

- Noise channel voltage level is greater than 5 volts is being indicated.

ACTION TAKEN WHEN THE DTC SETS

- The PCM will not illuminate the Malfunction Indicator Lamp (MIL).

- The PCM will store conditions which were present when the DTC set as Fail Records data only. This information will not be stored as Freeze Frame data.

- The PCM will use a calculated spark retard value to minimize knock during conditions when knock is likely to occur. The calculated value will vary based on engine speed and load.


CONDITIONS FOR CLEARING THE MIL/DTC

- A history DTC will clear after 40 consecutive warm-up cycles have occurred without a fault.

- DTC can be cleared by using the scan tool Clear Info function or by disconnecting the PCM battery feed.


DIAGNOSTIC AIDS

Check for the following conditions:

- Poor connection at the PCM. Inspect knock sensor and PCM connectors for backed out terminals, broken locks, and improperly formed or damaged terminals.

- Misrouted harness. Inspect the knock sensor harness to ensure that it is not routed too close to high voltage wires such as spark plug leads.

Reviewing the Fail Records vehicle mileage since the diagnostic test last failed may help determine how often the condition that caused the DTC to be set occurs. This may assist in diagnosing the condition.


TEST DESCRIPTION

Number(s) below refer to the step number(s) on the Diagnostic Table.

2. Ensures that the fault is present.

6. Checks for a false knock signal caused by a faulty knock sensor.

7. Ensures that the knock sensors are capable of producing a correct AC signal.

13. This vehicle is equipped with a PCM which utilizes an Electrically Erasable Programmable Read Only Memory (EEPROM). When the PCM is being replaced, the new PCM must be programmed.