P0325

DTC P0325 Knock Sensor (KS) Circuit Short Or Open:

Knock Sensor (KS) Circuit:

CIRCUIT DESCRIPTION
The Knock Sensor (KS) circuit consists of two knock sensors connected in parallel and a single wire to the Vehicle Control Module-A (VCM-A). Each knock sensor has a resistance value of about 8200 ohms. The VCM-A supplies a 5 volt reference to the sensors where because of the sensor resistance, it is cut in half to about 2.5 volts. When a knock occurs, a small Alternating Current (AC) voltage is generated by the knock sensors riding on top of the existing 2.5 volts. An AC voltage monitor in the VCM-A will detect this AC voltage and provide a signal to begin retarding spark until the knock diminishes. DTC P0325 is a type "B" DTC.

DTC P0325 WILL SET WHEN
DTC P0325 will set when knock sensor circuit voltage is less than 0.62V or greater than 3.18V for a period greater than 16 seconds.

ACTION TAKEN (VCM-A WILL DEFAULT TO)
When a DTC P0325 is set, the VCM-A will illuminate the Malfunction Indicator Lamp (MIL) after 2 consecutive faults.

DTC PO325 WILL CLEAR WHEN
The VCM-A will turn the MIL "OFF" after three consecutive trips without a fault condition present. A history DTC will be cleared if no fault conditions have been detected for forty warm-up cycles [coolant temperature has risen 22°C (40°F) from start-up coolant temperature and engine coolant temperature exceeds 71°C (160°F) that same ignition cycle] or the Tech 1 clearing feature has been used.

DTC CHART TEST DESCRIPTION
Number(s) below refer to circled number(s) on the diagnostic chart.
1. The VCM-A 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-A.
3. This step calls out the the knock sensor to be faulty.

DIAGNOSTIC AIDS
Check CKT 496 for a potential ground. 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