For 1990-2009 cars
Engine Controls Components
PCM MAF, IAC, Bank #1 KS, and Bank #2 KS VIN 1 and K
OBD II Symbol Description Notice
Handling ESD Sensitive Parts Notice

### Circuit Description

The knock sensors are used to detect engine detonation, allowing the PCM to retard Ignition Control (IC) spark timing based on the KS signal being received. The knock sensors produce an AC signal which rides on a 5 volts DC signal supplied by the PCM. The signal amplitude and frequency is dependent upon the amount of knock being experienced.

The PCM determines whether the knock sensors and related wiring are operating properly by monitoring the voltage level on the noise channel. The noise channel allows the PCM to diagnose the KS system by allowing the PCM to learn the amount of normal engine mechanical noise present. Normal engine noise varies depending on engine speed and load. Normal engine noise varies depending on engine speed and load. The PCM contains a replaceable Knock Sensor (KS) module. The KS module contains the circuitry that allows the PCM to diagnose the KS sensors and circuitry. If the KS module is missing or malfunctioning causing a continuous knock condition to be indicated, the PCM will set DTC P0325.

### Conditions for Setting the DTC

• | System voltage is greater than 9 volts.

• | The PCM detects a problem with the KS module circuitry that causes knock to be indicated continuously.

• | The above conditions are present for up to 2.5 seconds.

### Action Taken When the DTC Sets

• | The PCM will not illuminate the Malfunction Indicator Lamp (MIL).

• | The PCM will store conditions which were present when the DTC set as Fail Records data only. This information will not be stored as Freeze Frame data.

• | The PCM will use a calculated spark retard value to minimize knock during conditions when knock is likely to occur. The calculated value will vary based on engine speed and load.

### Conditions for Clearing the MIL/DTC

• | A History DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction.

• | The DTC can be cleared by using the scan tool Clear Info function.

### Diagnostic Aids

Check for the following conditions:

• | Poor connection at the PCM.

| Inspect the KS module connector for backed out terminals, broken locks, and improperly formed or damaged terminals.

• | Damaged or improperly installed KS module.

| Check for bent pins, deformed terminals, or the KS module not completely seated.

Reviewing the Fail Records vehicle mileage since the diagnostic test last failed may help determine how often the condition that caused the DTC to be set occurs. This may assist in diagnosing the condition.

### Test Description

Number(s) below refer to the step number(s) on the Diagnostic Table.

1. Ensures that the malfunction is present.

2. Checks for an improperly installed KS module.

3. This vehicle is equipped with a PCM which utilizes an Electrically Erasable Programmable Read Only Memory (EEPROM). When the PCM is being replaced, the new PCM must be programmed.

#### DTC P0325 - KS Module Circuit

Step | Action | Value(s) | Yes | No
--- | --- | --- | --- | ---
1 | Was the Powertrain On-Board Diagnostic (OBD) System Check performed? | -- | Go to Step 2 | Go to the 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. Refer to Engine Noise Diagnosis in Engine Mechanical.

1. Operate engine within conditions specified in diagnostic support. Refer to Conditions for Setting the DTC.
2. Using a scan tool, monitor Specific DTC info for DTC P0325 until the DTC P0325 test runs.

Note test result; does scan tool indicate DTC P0325 failed this ign?

--

Go to Step 4

Go to Step 3

3 |

1. Turn ON the ignition switch.
2. Review and record scan tool Fail Records data for DTC P0325.
3. Operate vehicle within Fail Records conditions.
4. Using a scan tool, monitor Specific DTC info for DTC P0325 until the DTC P0325 test runs.

Does scan tool indicate DTC P0325 test failed this ign?

--

Go to Step 4

Refer to Diagnostic Aids

4 |

1. Check the KS signal circuit(s) for incorrect routing near secondary wires.
2. If a problem is found, repair as necessary.

Was a problem found?

--

Go to Step 8

Go to Step 5

5 |

1. Check the KS module for not being fully seated or for incorrect installation.
2. If a problem is found, repair as necessary.

Was a problem found?

--

Go to Step 8

Go to Step 6

6 |

1. Replace the KS module.
2. Operate the engine within conditions specified in Conditions for Setting the DTC.
3. Using a scan tool, monitor Specific DTC info for DTC P0325 until the DTC P0325 test runs.

Note test result; does scan tool indicate DTC P0325 failed this ign?

--

Go to Step 7

Go to Step 8

7 | Replace the PCM. Important:: The replacement PCM must be programmed. Refer to Powertrain Control Module Replacement/Programming . Is action complete? | -- | Go to Step 8 | --
8 |

1. Review and record Fail Records data
2. Clear DTCs.
3. Operate the vehicle within Fail Records conditions.
4. Using a scan tool, monitor Specific DTC info for DTC P0325 until the DTC P0325 test runs.

Does the scan tool indicate DTC P0325 test failed this ign?

--

Go to Step 2

System OK