Circuit Description
The knock sensor (KS) system enables the powertrain control module (PCM) to control the ignition timing for the best possible performance while protecting the engine from potentially damaging levels of detonation. The KS is located at the left side of the engine block. The KS produces an AC voltage that varies depending on the vibration level during engine operation. The PCM adjusts the spark timing based on the amplitude and the frequency of the KS signal. The PCM receives the KS signal through a signal circuit. The KS ground is supplied by the engine block through the sensor housing. The PCM uses the KS signal to calculate an average voltage range value. If the system is operating normally, the PCM should monitor the KS voltage varying above and below the voltage range. If the PCM detects the KS signal voltage within the voltage range, or the KS signal is not present, this DTC will set.
Conditions for Running the DTC
| • | DTCs P0101, P0102, P0103, P0116, P0117, P0118, P0121, P0122, P0123, P0125, P0336, P0341, P0502, P0503, P1114, P1115, P1121, P1122 are not set. |
| • | The engine speed is between 1,000-5,000 RPM. |
| • | The engine has been running for a minimum of 30 seconds. |
| • | The throttle angle is more than 15 percent . |
| • | The engine load is more than 45 percent . |
| • | The engine coolant temperature (ECT) is more than 60°C (140°F). |
| • | The maximum spark retard is less than 15 degrees. |
| • | The system voltage is more than 9 volts. |
Conditions for Setting the DTC
| • | The PCM detects a KS signal voltage within the average voltage range for at least 10 seconds. |
| • | The engine run time is more than 30 seconds. |
Action Taken When the DTC Sets
| • | The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails. |
| • | The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records. |
Conditions for Clearing the MIL/DTC
| • | The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail. |
| • | A current DTC, Last Test Failed, clears when the diagnostic runs and passes. |
| • | A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic. |
| • | Clear the MIL and the DTC with a scan tool. |
Diagnostic Aids
| • | Inspect the KS for physical damage. A KS that is dropped or damaged may cause a DTC to set. |
| • | Inspect the KS for proper installation. A KS that is loose or over torqued may cause a DTC to set. The KS should be free of thread sealant. The KS mounting surface should be free of burrs, casting flash, and foreign material. |
| • | For an intermittent condition, refer to Intermittent Conditions . |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
-
A fault in the 12-volt reference circuit of the 24X CKP sensor or the CMP sensor can cause this DTC to set.
-
Tapping on the engine block will simulate an engine knock.
Step | Action | Values | Yes | No | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics Connector End View Reference: Engine Controls Connector End Views or Powertrain Control Module Connector End Views | ||||||||||||||
1 | Did you perform the Diagnostic System Check-Engine Controls? | -- | Go to Step 2 | |||||||||||
2 |
Does the scan tool display any other DTCs set? | -- | Go to Step 3 | |||||||||||
Monitor the 24X Crank Sensor parameter with the scan tool. Is the 24X Crank Sensor parameter incrementing? | -- | Go to Step 4 | Go to DTC P0336 | |||||||||||
4 |
Important: If an engine mechanical noise can be heard, repair the condition before proceeding with this diagnostic. Refer to Symptoms - Engine Mechanical in Engine Mechanical -- 3.4L.
Does the DTC fail this ignition? | -- | Go to Step 5 | Go to Diagnostic Aids | ||||||||||
5 |
Is the resistance within the specified range? | 93-107 Kohms | Go to Step 6 | Go to Step 10 | ||||||||||
Important: Do not tap on plastic engine components. Is any signal indicated on the DMM while tapping on the engine block near the KS? | -- | Go to Step 7 | Go to Step 10 | |||||||||||
7 |
Did you find and correct the condition? | -- | Go to Step 12 | Go to Step 8 | ||||||||||
8 | Test for an intermittent and for a poor connection at the KS. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 12 | Go to Step 9 | ||||||||||
9 | Test for an intermittent and for a poor connection at the PCM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 12 | Go to Step 11 | ||||||||||
10 | Replace the KS. Refer to Knock Sensor Replacement . Did you complete the replacement? | -- | Go to Step 12 | -- | ||||||||||
11 | Replace the PCM. Refer to Powertrain Control Module Replacement . Did you complete the replacement? | -- | Go to Step 12 | -- | ||||||||||
12 |
Does the DTC fail this ignition? | -- | Go to Step 2 | Go to Step 13 | ||||||||||
13 | Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? | -- | System OK | |||||||||||
