GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2006 🢒 Colorado Pickup - 2WD 🢒 Brakes 🢒 Park Brake 🢒 DTC P0326

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 PCM monitors two sensors. Each sensor is located on the intake side of the engine block. KS 1 is located at the front of the engine. The sensors produce an AC voltage signal that varies at all engine speeds and loads. 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 PCM through a low reference circuit. The PCM uses the KS signal to calculate the average voltage and then assigns a voltage range value. The PCM should monitor a normal KS signal within the noise channel. When the PCM detects a KS signal that varies outside of the noise channel, the PCM will retard the spark timing until the knock goes away. If the PCM is operating on large amounts of spark retard and is unable to eliminate the knock, this DTC will set.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC P0326 Knock Sensor (KS) Performance

Conditions for Running the DTC
    • The engine speed is more than 1,800 RPM.
    • The manifold absolute pressure (MAP) is more than 55 kPa.
    • DTC P0326 runs continuously when the above conditions are met.

Conditions for Setting the DTC
    • The KS signal indicates an engine knock is present.
    • The PCM commanded spark retard at a given engine load and speed is more than the calibrated value for 8 seconds.

Action Taken When the DTC Sets
    • The control module stores the DTC information into memory when the diagnostic runs and fails.
    • The malfunction indicator lamp (MIL) will not illuminate.
    • The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Failure Records.
    • The driver information center, if equipped, may display a message.

Conditions for Clearing the DTC
    • 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 non-emission related diagnostic.
    • Clear the DTC with a scan tool.

Step

Action

Yes

No

Schematic Reference: Engine Controls Schematics

Connector End View Reference: Powertrain Control Module Connector End Views or Engine Controls Connector End Views

1

Did you perform the Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle

2
  1. Inspect for a loose or broken vehicle accessory and/or accessory bracket.
  2. If a condition is found, repair as necessary.

Did you find and correct the condition?

Go to Step 4

Go to Step 3

3
  1. Start the engine.
  2. Inspect for excessive engine mechanical noise. Refer to Symptoms - Engine Mechanical in Engine Mechanical - 3.5L (L52).
  3. If a condition is found, repair as necessary.

Did you find and correct the condition?

Go to Step 4

Go to Detonation/Spark Knock

4
  1. Clear the DTCs with a scan tool.
  2. Turn OFF the ignition for 30 seconds.
  3. Start the engine.
  4. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records.

Does the DTC fail this ignition?

Go to Step 2

Go to Step 5

5

Observe the Capture Info with a scan tool.

Are there any DTCs that have not been diagnosed?

Go to Diagnostic Trouble Code (DTC) List - Vehicle

System OK