DTC P0325 Knock Sensor (KS) Circuit. GMC Truck Sonoma Pickup

For 1990-2009 cars only

Makes 🢒 GMC_Truck 🢒 2000 🢒 Sonoma Pickup - 2WD 🢒 DTC 🢒 DTC P0325 Knock Sensor (KS) Circuit

Engine Controls Components
Ignition Controls
OBD II Symbol Description Notice
Powertrain Control Module Connector End Views
Handling ESD Sensitive Parts Notice

Circuit Description

The knock sensor (KS) system detects for an engine detonation. The knock sensor produces an AC voltage signal. The amplitude and the frequency of the AC voltage signal is dependent upon the knock level being detected. This signal then travels to the KS module that is an internal part of the powertrain control module (PCM). If knock is detected, the PCM will retard the spark timing based on the signal from the KS.

Conditions for Running the DTC

•	Engine run time is more than 20 seconds.

•	The engine coolant temperature (ECT) is more than 56°C (131°F).

•	Engine speed is above 1600 RPM.

•	The manifold absolute pressure (MAP) is more than 35 kPa.

•	DTCs P0122, P0123 are not set.

•	Engine vacuum is less than 45 kPa.

Conditions for Setting the DTC

•	The KS voltage and variation is not within normally expected ranges.

•	The above conditions are present for more than 15 seconds.

Action Taken When the DTC Sets

•	The malfunction indicator lamp (MIL) will illuminate.

•	The PCM will record operating conditions at the time the diagnostic fails. The Freeze Frame and Failure Records buffers will store this information.

•	A history DTC is stored.

•	The PCM will default to a more conservative spark timing.

Conditions for Clearing the MIL/DTC

•	The MIL will turn OFF after 3 consecutive ignition cycles in which the diagnostic runs without a fault.

•	A history DTC will clear after 40 consecutive warm up cycles without a fault.

•	A scan tool can clear the DTCs.

Diagnostic Aids

•	Check and correct any abnormal engine noise before using the diagnostic table.

•	Thoroughly check any suspected circuitry for the following conditions:

-	Backed out terminals

-	Improper mating

-	Broken locks

-	Improperly formed connectors

-	Damaged terminals

-	Poor terminal to wiring connections

-	Physical damage to the wiring harness

Step

Action

Values

Yes

Did you perform the Powertrain On-Board Diagnostic (OBD) System Check?

Go to Step 2

Go to

Powertrain On Board Diagnostic (OBD) System Check

Start the engine.
Listen to the engine while raising and lowering the engine speed.
Turn ON the A/C.

Is a knock or audible noise present?

Go to Step 3

Go to Step 4

Turn OFF the ignition.
Check and repair the following conditions:

•	Mechanical engine problem

•	Loose bracket

•

Component

Is the action complete?

Go to Step 12

Turn OFF the ignition.
Disconnect the KS electrical connector.
Connect a DMM to ground.
Measure the resistance of the KS.

Is the resistance within the specified value?

90K-110Kohms

Go to Step 5

Go to Step 10

Disconnect the PCM connector.
Check the resistance from the KS connector to the PCM connector with a DMM set to ohms scale.

Is the resistance within the specified value?

0-5ohms

Go to Step 6

Go to Step 9

Connect the DMM to ground.
Probe the signal circuit with the DMM set to ohms scale.

Does the DMM display the specified value?

Go to Step 7

Go to Step 9

Turn ON the ignition.
Measure the voltage of the signal circuit with a DMM connected to ground.

Is the voltage above the specified value?

0-.5 V

Go to Step 9

Go to Step 8

Check the knock sensor (KS) electrical connector for poor terminal contact.
Repair the electrical connection as necessary. Refer to Wiring Repairs in Wiring Systems.

Was a repair necessary?

Go to Step 12

Go to Step 11

Repair the open, short to voltage or short to ground in the KS signal circuit.

Is the action complete?

Go to Step 12

Replace the knock sensor (KS). Refer to Knock Sensor Replacement .

Is the action complete?

Go to Step 12

Important: The replacement PCM must be programmed.

Replace the PCM. Refer to Powertrain Control Module Replacement/Programming .

Is the action complete?

Go to Step 12

Clear the DTCs with the scan tool.
Start the engine.
Idle the engine at the normal operating temperature.
Operate the vehicle within the Conditions for Setting this DTC as specified in the supporting text.

Does the scan tool indicate that this diagnostic has Ran and Passed?

Go to Step 13

Go to Step 2

Check to see if any DTCs are set.

Does the scan tool display any DTCs that you have not diagnosed?

Go to applicable DTC table

System OK