GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 1996 🢒 Caprice 🢒 Engine 🢒 Engine Controls - 4.3L (Caprice Only) and 5.7L 🢒 DTC P0325 Knock Sensor Module Performance

Circuit Description

A removable Knock Sensor (KS) module is located in the PCM. The KS module monitors both knock sensors to determine if detonation is present. If the KS module determines that excessive knock (detonation) is present, the PCM will retard the spark timing based on the signals from the KS module. When knock is present, the KS module voltage input signal to the PCM goes low. The PCM will then retard timing until no knock is present. When the KS module is missing or malfunctioning, the KS circuit voltage going to the PCM will go low. The PCM interprets this low signal as spark knock.

Conditions for Setting the DTC
    • The PCM detects that the KS module is missing
    • A malfunction with the KS module or circuits to the module are faulty.

Action Taken When the DTC Sets
    • The DTC will be stored in the PCM memory when the diagnostic runs and fails.
    • The Malfunction Indicator Lamp (MIL) will not illuminate.
    • The PCM will record operating conditions at the time the diagnostic fails. This information will be stored in Failure Records.

Conditions for Clearing the MIL/DTC
    • 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.
    • A last test failed (Current DTC) will clear when the diagnostic runs and does not fail.
    • PCM battery voltage is interrupted.
    • Using a scan tool.

Diagnostic Aids
    • If the diagnostic test does not run, review Conditions for Setting the DTC criteria.
    • Check the KS module terminals for corrosion. If corrosion is found, inspect KS Module access cover seal for cuts and nicks.

For intermittents, refer to Symptoms .

Test Description

Number(s) below refer to step numbers on the diagnostic table.

  1. Check the KS module terminals for corrosion. If corrosion is found, replace the PCM and the KS module.

    2.

  2. If the PCM is at fault, the original KS module must be installed in the new PCM.

Step

Action

Value(s)

Yes

No

1

Was the Powertrain On-Board Diagnostic (OBD) System Check performed?

--

Go to Step 2

Go to Powertrain On Board Diagnostic (OBD) System Check

2

Important: If an engine knock can be heard, repair the engine mechanical problem before proceeding with this diagnostic.

  1. Start and idle the engine for 2 minutes.
  2. Using the scan tool, select DTC, Specific, then enter the DTC number which was set.

Does the scan tool indicate that this diagnostic failed this ignition?

--

Go to Step 3

Go to Diagnostic Aids

3

  1. Turn the ignition OFF.
  2. Check the PCM for a missing module, for the module not being fully seated or for incorrect installation.

Was a problem found and corrected?

--

Go to Step 6

Go to Step 4

4
  1. Replace the KS module. Refer to Knock Sensor Module Replacement .
  2. Start and idle the engine for 2 minutes.
  3. Using the scan tool, select DTC, Specific, then enter the DTC number which was set.

Does the scan tool indicate that this diagnostic failed this ignition?

--

Go to Step 5

Go to Step 6

5

Important:: Replacement PCM must be programmed. Refer to Powertrain Control Module Replacement/Programming .

Replace the PCM.

Is the action complete?

--

Go to Step 6

--

6
  1. Using the scan tool, select DTC, Clear Info.
  2. Start the engine and idle at normal operating temperature.
  3. Select DTC, Specific, then enter the DTC number which was set.
  4. Operate the vehicle within the conditions for setting this DTC as specified in the supporting text, if applicable.

Does the scan tool indicate that this test ran and passed?

--

Go to Step 7

Go to Step 2

7

Using the scan tool, select Capture Info, Review Info.

Are any DTCs displayed that have not been diagnosed?

--

Go to the applicable DTC table

System OK