• | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. |
• | Review Strategy Based Diagnosis for an overview of the diagnostic approach. |
• | Diagnostic Procedure Instructions provides an overview of each diagnostic category. |
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
---|---|---|---|---|
Knock Sensor Signal | P0327, P0328, P0332, P0333 | P0325, P0330 | P0327, P0332 | P0326 |
The knock sensor (KS) system enables the engine control module (ECM) to control the ignition timing for the best possible performance while protecting the engine from potentially damaging levels of detonation. The ECM monitors 2 separate KS, one on each side of the engine block. Each KS produces an AC voltage that varies, depending on the vibration levels detected during engine operation. The ECM receives the KS signal through 2 isolated signal circuits for each KS. The ECM adjusts the spark timing based on the amplitude and frequency of each KS signal.
This DTC runs continuously when the engine speed is greater than or equal to 1,500 RPM and the engine load is greater than a calibrated amount.
This DTC runs continuously when:
• | The engine speed is greater than or equal to 500 RPM. |
• | The MAP is greater than 55 kPa. |
• | DTCs P0120, P0121, P0122, or P0123 are not set. |
The DTCs run continuously when:
• | The engine coolant temperature (ECT) is greater than -40°C (-40°F). |
• | The engine run time is greater than 1 second. |
• | The power take-off (PTO) is not active. |
The ECM has detected an internal circuitry fault.
The KS signal circuits are open or shorted together for 5 seconds.
• | The KS signal indicates an engine knock is present. |
• | The ECM has commanded the spark retard to a value, which is more than the calibrated value, for a specific engine load and speed. |
• | The above conditions exist for more than 5 seconds. |
The KS signal circuits are shorted to voltage or ground.
• | DTCs P0324, P0325, P0326, P0327, P0328, P0330, P0332, and P0333 are Type B codes. |
• | The ignition timing is retarded to reduce the potential of engine damaging spark knock. |
DTCs P0324, P0325, P0326, P0327, P0328, P0330, P0332, and P0333 are Type B codes.
• | 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 mounting surface should be free of burs, casting flash, and foreign material. |
Electronic Ignition (EI) System Description
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Control Module References for scan tool information
J 35616 GM Approved Terminal Test Kit
Important: If DTC P0325, P0326, P0327, P0328, P0330, P0332, or P0333 are also set, diagnostics those DTCs first.
DTC P0324 indicates an internal control module circuitry failure. Replace the ECM.
• | The KS signal circuit, terminal A |
• | The KS signal circuit, terminal B |
⇒ | If less than the specified range, test the circuits for a short to ground or an open/high resistance. If the circuits test normal, replace the ECM. |
⇒ | If greater than the specified range, test the circuits for a short to voltage. If the circuits test normal, replace the ECM. |
Important: If DTC P0325, P0327, P0328, P0330, P0333, P0335, or P0336 are also set, diagnostics those DTCs first. |
• | Inspect for a loose or broken engine mount, engine mounted accessory, or accessory mounting bracket. |
• | Inspect for excessive engine mechanical noise. Refer to Symptoms - Engine Mechanical . |
Important: DO NOT tap on plastic engine components.
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.