Circuit Description
The knock sensor (KS) system monitors the KS in order to determine if pre-detonation is present. If the KS system determines that excessive knock or pre-detonation is present, the powertrain control module (PCM) retards the spark timing based on the signals from the KS system. When knock is present, the KS system voltage input signal to the PCM goes low. The PCM then retards timing until no knock is present. When the KS system is malfunctioning, the KS circuit voltage going to the PCM goes low. The PCM interprets this low signal as spark knock.
Conditions for Running the DTC
| • | The engine speed is between 1,500 RPM and 3,000 RPM. |
| • | The engine coolant temperature is more than 60°C (135°F). |
| • | The throttle angle is more than 0.5 percent. |
| • | The engine run time is more than 20 seconds. |
Conditions for Setting the DTC
| • | A malfunction with the KS system or circuits within the PCM are faulty. |
| • | All above conditions are present for 3.0 seconds. |
Action Taken When the DTC Sets
| • | The powertrain control module (PCM) stores the DTC information into memory when the diagnostic runs and fails. |
| • | The malfunction indicator lamp (MIL) will not illuminate. |
| • | The PCM records the operating conditions at the time the diagnostic fails. The PCM stores this information in the Failure Records. |
Conditions for Clearing the DTC
| • | A last test failed, or current DTC, clears when the diagnostic runs and does not fail. |
| • | A history DTC will clear after 40 consecutive warm-up cycles, if no failures are reported by this or any other non-emission related diagnostic. |
| • | Use a scan tool in order to clear the DTC. |
Diagnostic Aids
Important:
• Remove any debris from the PCM connector surfaces before servicing
the PCM. Inspect the PCM connector gaskets when diagnosing or replacing the
PCM. Ensure that the gaskets are installed correctly. The gaskets prevent
contaminant intrusion into the PCM. • For any test that requires probing the PCM or component
harness connectors, use the J 35616
connector test adapter kit. Using this kit prevents
any damage to the harness connector terminals. Refer to
Using Connector Test Adapters
in
Wiring Systems for procedures.
| • | If the diagnostic test does not run, review the Conditions for Running the DTC. |
| • | For an intermittent condition, refer to Symptoms . |
Test Description
The number below refers to the step number on the diagnostic table.
Step | Action | Values | Yes | No |
|---|---|---|---|---|
1 | Did you perform the Powertrain On-Board Diagnostic (OBD) System Check? | -- | ||
|
Important:: The replacement PCM must be programmed. Replace the PCM. Refer to Powertrain Control Module Replacement/Programming . Is the action complete? | -- | -- | ||
3 |
Does the scan tool indicate that this test ran and passed? | -- | ||
4 | Select the Capture Info option and the Review Info option using the scan tool. Does the scan tool display any DTCs that you have not diagnosed? | -- | Go to the applicable DTC table | System OK |
