P0328

DTC P0328 Knock Sensor (KS) Circuit Open:

Knock Sensor (KS) Circuit Open:

Circuit Description
The Knock Sensor (KS) circuit consists of two knock sensors connected in parallel and a single wire to the VCM. Each knock sensor has a resistance value of about 8600 ohms. The VCM supplies a 5 volt reference to the sensors when because of the sensor resistance, it is cut in half to about 2.5 volts. When a knock occurs, a small AC voltage is generated by the knock sensors riding on top of the existing 2.5 volts. An AC voltage monitor in the VCM will detect this AC voltage and provide a signal to begin retarding spark until the knock diminishes.

DTC P0328 Will Set When
DTC P0328 will set when knock sensor circuit is greater than 3.1 volts for a period greater than 16 seconds.

Action Taken (VCM will default to)
No action taken.

DTC PO328 Will Clear When
Conditions for fault are no longer present and Tech 1 clear DTCs function is used or 50 ignition switch keycycles have passed with no further faults or ignition switch is turned "OFF" and Fuse #9 (ECM B) fuse is removed for 10 seconds.

DTC Chart Test Description
Number(s) below refer to circled number(s) on the diagnostic chart.

1. The VCM applies 5 volts on CKT 496 which should be present at the knock sensor connectors when the sensors are disconnected.

2. By verifying that knock sensor resistance is within specifications, it can be determined that the problem lies with the connector, sensor installation or VCM.

3. An improperly installed knock sensor can prevent the knock sensor from grounding to the block.

Diagnostic Aids
Check CKT 496 for a potential open.

Check knock sensor connections for proper fit. A connector that is fatigued may not fit correctly as the underhood temperature increases.

Also, check for proper installation of PROM (MEM-CAL). Refer to "Intermittents". - Intermittent Malfunctions