Circuit Description
The knock sensor produces an AC voltage at all engine speeds and loads. The PCM then adjusts the spark timing based on the amplitude and frequency of the KS signal. The PCM uses the KS signal to calculate the average voltage. The PCM then assigns a voltage value. The PCM checks the knock sensor and the related wiring by comparing the actual knock signal to the assigned voltage range. A normal KS signal should remain within the assigned voltage range. This DTC will set if the KS signal is outside the assigned voltage range or is not present.
Conditions for Running the DTC
| • | DTCs P0117, P0118, P0121, P0122, P0123, P0125, P1114, P1115, P1121, and P1122 are not set. |
| • | The engine coolant temperature (ECT) is more than 60°C (140°F). |
| • | The engine run time is more than 10 seconds. |
| • | The manifold absolute pressure (MAP) is less than 44 kPa. |
| • | The engine speed is between 2,000 and 3,000 RPM. |
| • | The system voltage is more than 10 volts.. |
Conditions for Setting the DTC
The knock sensor signal is outside the assigned range or not present.
Action Taken When the DTC Sets
| • | The engine power is reduced due to spark retard while the DTC is current. |
| • | The PCM illuminates the malfunction indicator lamp (MIL) during the second consecutive trip in which the diagnostic test has run and failed . |
| • | The PCM stores the conditions which were present when the DTC set as Freeze Frame/Failure Records data. |
Conditions for Clearing the MIL/DTC
| • | The PCM turns OFF the MIL during the third consecutive trip in which the diagnostic has run and passed. |
| • | A history DTC clears after 40 consecutive warm-up cycles have occurred without a malfunction. |
| • | The DTCs can be cleared with a scan tool. |
Diagnostic Aids
| • | The knock sensor must be correctly tightened to 25N·m (19 lb ft). |
| • | The mounting between the sensor and the engine must be free of burrs, casting flash, and foreign material. |
| • | The knock sensor head must be clear from hoses, brackets, and engine wiring. |
| • | If an intermittent is suspected, refer to Intermittent Conditions . |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
-
This step verifies the malfunction is present.
-
This step verifies that the knock sensor is capable of detecting detonation and checks the wiring to the PCM. Striking the lift bracket with a non-metallic object should produce a signal that the knock sensor detects.
Step | Action | Values | Yes | No |
|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics | ||||
1 | Did you perform the Diagnostic System Check-Engine Controls? | -- | Go to Step 2 | |
Important: If an engine knock can be heard, repair the engine mechanical condition before proceeding with this diagnostic. Does the DTC fail this ignition? | -- | Go to Step 3 | Go to Intermittent Conditions | |
Does the DMM display a fluctuating frequency while tapping on the block? | -- | Go to Step 6 | Go to Step 4 | |
4 |
Did you find and correct the condition? | -- | Go to Step 11 | Go to Step 5 |
5 | Inspect for a poor connection at the knock sensor harness connector. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 11 | Go to Step 9 |
6 | Test for a short to ground and for a short to voltage in the KS signal circuit. Refer to Testing for Short to Ground and Testing for a Short to Voltage in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 11 | Go to Step 7 |
7 | Test for a short to ground and a short to voltage in the KS low reference circuit. Refer to Testing for Short to Ground and Testing for a Short to Voltage in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 11 | Go to Step 8 |
8 | Inspect for a poor connection at the harness connector of the PCM. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 11 | Go to Step 10 |
9 | Replace the knock sensor. Refer to Knock Sensor Replacement . Did you complete the replacement? | -- | Go to Step 11 | -- |
10 | Replace the PCM. Refer to Powertrain Control Module Replacement . Did you complete the replacement? | -- | Go to Step 11 | -- |
11 |
Does the diagnostic test run and pass? | -- | Go to Step 12 | Go to Step 2 |
12 | Use a scan tool in order to observe the Stored Information, Capture Info. Does the scan tool display any DTCs that you have not diagnosed? | -- | System OK | |
