System Diagnosis - Knock Sensor (KS)

Knock Sensor (KS) Chart:

Knock Sensor (KS) Circuit:

CIRCUIT DESCRIPTION:
The Knock Sensor (KS) system consist of two knock sensors with one wire that goes directly to the PCM. The PCM check consists of monitoring CKT 496 for a voltage that is more than 0.63 volt and less than 3.1 volts.
If the voltage is either too high or too low for 16 or more seconds, DTC 43 will set.

CHART TEST DESCRIPTION:
Number(s) below refer to circled number(s) on the diagnostic chart.
1. The first test is to determine if the system is functioning at the present time.
2. Test two determines the state of the 5 volt reference voltage applied to the knock sensor circuit.
3. This diagnosis CKT 496 and the knock sensor.

DIAGNOSTIC AIDS:
The PCM applies 5 volts to CKT 496. A 8200 ohm resistor in the knock sensors reduces the voltage to about 2.5 volts. When knock occurs, the knock sensor produces a small AC voltage that rides on top of the 2.5 volts already applied. An AC voltage monitor, in the PCM, is able to read this signal as knock and incrementally retard spark.
If the KS system checks OK, but detonation is the complaint, refer to Diagnosis By Symptom/Detonation/Spark Knock. Detonation/Spark Knock/Pings