P0330
P0330-KNOCK SENSOR 2 CIRCUIT
For complete wiring diagrams refer to Diagrams/Electrical.
Theory of Operation
Knock is the spontaneous auto-ignition of the remaining fuel/air mixture in the engine combustion chamber that occurs after normal combustion has started. It can occur under extreme vehicle operating conditions such as high engine temperature, high MAP, low humidity, and heavy loads to the engine. Knock is caused by excessive spark advance for the given engine operating conditions. Severe, continuous knock may be caused by carbon deposits, bad gasoline, and/or low octane fuel. Avoiding light audible knock is important for customer satisfaction while preventing excessive knock is important to protect engine components. The output voltage from the knock circuit represents the strength of the engine knock and is read by the engine controller. The knock system output voltage is not zero due to engine background noise, even when knock is not present. This background noise varies from engine to engine depending on the engine age, engine temperature, engine speed, engine load, and other engine operating conditions. When the engine is operated under high load conditions where knock is possible, the knock voltage is tested to decide if it exceeds the knock voltage threshold. Knock has occurred when the knock voltage is at or above this knock threshold. When knock is detected a calibrated short term knock spark retard to be subtracted from the spark advance is calculated. The amount of retarded spark advance is based off a calibrated severity of the knock event. Severity is the amount of knock voltage that is greater than the knock threshold voltage level. This retarded spark advance is used in the next ignition event to prevent further knock events. If knock continues, an additional amount of short term spark advance retard is added. The additional amount of short term spark advance retard is based off a second calibrated severity amount. When short term knock spark retard compensation continues for a calibrated length of time and exceeds a retard threshold, long term knock spark retard compensation is initiated. If knock persists, additional short term knock spark retard is used besides the long term knock spark retard. When knock stops, short term knock spark retard is eliminated, the long term knock spark retard is reduced by a calibrated amount to recover some previously retarded spark advance. This decreases spark retard to improve engine performance.
- When Monitored:
This monitor runs above 2000 rpm, under open throttle conditions. The Knock diagnostic does not run at idle or during decelerations. The high voltage test runs all the times the engine is running.
- Set Condition:
The High voltage fault will set at 4.8 volts. Two Trip Fault. Three good trips to turn off the MIL.
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding.
Diagnostic Test
1. ACTIVE DTC
Start the engine and allow it to reach normal operating temperature.
WARNING: When the engine is operating, do not stand in direct line with the fan. Do not put your hands near the pulleys, belts, or fan. Do not wear loose clothing. Failure to follow these instructions can result in personal injury or death.
NOTE: It may be necessary to test drive the vehicle within the DTC monitoring conditions in order for this DTC to reset.
With the scan tool, select View DTCs.
Is the DTC Active or Pending at this time?
Yes
- Go To 2
No
- Refer to the INTERMITTENT CONDITION Diagnostic Procedure. Intermittent Condition
2. (K242) KNOCK SENSOR NO.2 SIGNAL SHORTED TO VOLTAGE
Turn the ignition off.
Disconnect the No.2 Knock Sensor harness connector.
Disconnect the C2 PCM harness connector.
Ignition on, engine not running.
Measure the voltage on the (K242) Knock Sensor No.2 Signal circuit in the Knock Sensor harness connector.
Is there any voltage present?
Yes
- Repair the short to voltage in the (K242) Knock Sensor No.2 Signal circuit.
- Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
No
- Go To 3
3. (K242) KNOCK SENSOR NO.2 SIGNAL CIRCUIT OPEN
Turn the ignition off.
CAUTION: Do not probe the PCM harness connectors. Probing the PCM harness connectors will damage the PCM terminals resulting in poor terminal to pin connection. Install Miller Special Tool #8815 to perform diagnosis.
Measure the resistance of the (K242) Knock Sensor No.2 Signal circuit from the Knock Sensor harness connector to the appropriate terminal of special tool #8815.
Is the resistance below 5.0 ohms?
Yes
- Go To 4
No
- Repair the open in the (K242) Knock Sensor No.2 Signal circuit.
- Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
4. (K924) KNOCK SENSOR NO.2 RETURN CIRCUIT OPEN
Measure the resistance of the (K924) Knock Sensor No.2 Return circuit from the Knock Sensor harness connector to the appropriate terminal of special tool #8815.
Is the resistance below 5.0 ohms?
Yes
- Go To 5
No
- Repair the open in the (K924) Knock Sensor No.2 Return circuit.
- Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
5. (K242) KNOCK SENSOR NO.2 SIGNAL SHORTED TO THE (K924) KNOCK SENSOR NO.2 RETURN CIRCUIT
Measure the resistance between the (K242) Knock Sensor No.2 Signal circuit and the (K924) Knock Sensor No.2 Return circuit in the Knock Sensor harness connector.
Is the resistance below 100 ohms?
Yes
- Repair the short between the (K242) Knock Sensor No.2 Signal circuit and the (K924) Knock Sensor No.2 Return circuit.
- Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
No
- Go To 6
6. (K242) KNOCK SENSOR NO.2 SIGNAL SHORTED TO GROUND
Measure the resistance between ground and the (K242) Knock Sensor No.2 Signal circuit in the Knock Sensor harness connector.
Is the resistance below 100 ohms?
Yes
- Repair the short to ground in the (K242) Knock Sensor No.2 Signal circuit.
- Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
No
- Go To 7
7. KNOCK SENSOR
Replace the Knock Sensor.
Ignition on, engine not running.
With the scan tool, erase DTC.
Attempt to operate the vehicle using the information noted in the Freeze Frame.
With the scan tool, read DTCs.
Does the scan tool display the DTC that was previously erased?
Yes
-
NOTE: Before continuing, check the PCM harness connector terminals for corrosion, damage, or terminal push out. Repair as necessary. Replace and program the Powertrain Control Module.
- Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
No
- Test Complete.