P0326

DTC P0326 Knock Sensor (KS) Circuit - Range/rationality:

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 when 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 P0326 is a type "B" DTC.

DTC PO326 WILL SET WHEN
Knock sensor is not detecting vibration and the AC voltage is less than a minimum value.
^ Engine Run Time is greater than 2 min.
^ Engine Coolant Temperature (ECT) is greater than 60°C (140°F).
^ RPM is greater than 2200 RPM.
^ "Closed Loop."
^ No ECT DTCs.
^ No Throttle Position (TP) sensor DTCs.
^ TP angle is greater than 6%.
^ Knock sensor voltage less than 0.30 volts or greater than 4.98 volts for at least 5 seconds.

ACTION TAKEN (VCM-A WILL DEFAULT TO)
The VCM-A will turn "ON" the Malfunction Indicator Lamp (MIL) after 2 consecutive failures with the fault present.

DTC PO326 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. 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

NOTE: Idle must be <900 RPM for 5 seconds before diagnostic will run.