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Diagnostic Aids

Perform this test only when directed by QUICK TEST. This test is intended to diagnose the following:

Knock Sensor (KS).
KS harness circuit.
PCM.

To prevent replacement of good components, be aware the following non-EEC related areas may be at fault:

Poor fuel quality.
Ignition timing.
Engine mechanical condition.

CIRCUIT PIN IDENTIFICATION

Circuit	PCM Pin No.	Wire Color
KS	63	White
GND	45	Black/Red

NOTE: Freeze frame data will not be stored in the ECM for the knock sensor. The MIL will not light for a knock sensor malfunction.

DTC P0325

DTC P0325 indicates that spark knock has occurred and knock sensor failed to detect. Possible causes for this fault are as follows:
- PCM not receiving signal.
- Open or short in harness.
- Faulty knock sensor.
- Faulty PCM.
Turn ignition off. Disconnect PCM harness connector. Disconnect KS harness connector. Measure resistance of KS signal circuit between PCM harness connector and KS harness connector. See Fig 1. See CIRCUIT PIN IDENTIFICATION table. If resistance is less than 5 ohms, go to next step. If resistance is not less than 5 ohms, repair open in circuit.

Check KS Circuit For Short To Ground

Measure resistance between GND and KS circuits at PCM harness connector. If resistance is greater than 10 k/ohms, go to next step. If resistance is not greater than 10 k/ohms, repair short in circuit.

Fig 1: Identifying Knock Sensor Circuits & Connector Terminals
Courtesy of FORD MOTOR CO.

Check KS Circuits For Short To Power

Measure resistance between KS, VPWR and KAPWR circuits at PCM harness connector. If each resistance measurement is greater than 10 k/ohms, go to next step. If each resistance measurement is not greater than 10 k/ohms, repair short in circuit.

Check Resistance Of KS

Measure resistance between ground and KS circuit at KS terminal. If resistance is 500-620 k/ohms, replace PCM. If resistance is not 500-620 k/ohms, replace KS.