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Toyota Sienna Service Manual: Knock Sensor 1 Circuit Low Input

Knock Sensor 1 Circuit Low Input

DESCRIPTION

A flat type knock sensor (non-resonant type) has a structure that can detect vibrations over a wide band of frequencies: between approximately 6 kHz and 15 kHz.

Knock sensors are fitted onto the engine block to detect engine knocking.

The knock sensor contains a piezoelectric element which generates a voltage when the engine block vibrates due to knocking. Any occurrence of engine knocking can be suppressed by delaying the ignition timing.

Knock Sensor 1 Circuit Low Input

HINT:

When any of DTCs P0327, P0328, P0332 and P0333 are set, the ECM enters fail-safe mode. During failsafe mode, the ignition timing is delayed to its maximum retardation. Fail-safe mode continues until the ignition switch is turned off.

Reference: Inspection using an oscilloscope

Knock Sensor 1 Circuit Low Input

The correct waveform is as shown.

MONITOR DESCRIPTION

The knock sensor, located on the cylinder block, detects spark knock. When a spark knock occurs, the piezoelectric element of the sensor vibrates. When the ECM detects a voltage in this frequency range, it retards the ignition timing to suppress the spark knock.

The ECM also senses background engine noise with the knock sensor and uses this noise to check for faults in the sensor. If the knock sensor signal level is too low for more than 10 seconds, or if the knock sensor output voltage is outside the normal range, the ECM interprets this as a fault in the knock sensor and sets a DTC.

MONITOR STRATEGY

MONITOR STRATEGY

TYPICAL ENABLING CONDITIONS

TYPICAL ENABLING CONDITIONS

TYPICAL MALFUNCTION THRESHOLDS

TYPICAL MALFUNCTION THRESHOLDS

WIRING DIAGRAM

WIRING DIAGRAM

INSPECTION PROCEDURE

HINT:

1 READ VALUE OF DTC OUTPUT (CHECK KNOCK SENSOR CIRCUIT)

READ VALUE OF DTC OUTPUT (CHECK KNOCK SENSOR CIRCUIT)

(a) Disconnect the EA1 connector.

(b) Using lead wires, connect the connectors as follows.

(c) Warm up the engine.

(d) Run the engine at 3000 rpm for 10 seconds or more.

(e) Connect the intelligent tester to the DLC3.

(f) Turn the ignition switch to the ON position and turn the intelligent tester on.

(g) Select the items: DIAGNOSIS / ENHANCED OBD II / DTC INFO / CURRENT CODES.

(h) Read the DTCs.

Result

(i) Reconnect the EA1 connector.

2 CHECK HARNESS OR CONNECTOR (EA1 CONNECTOR - ECM)

CHECK HARNESS OR CONNECTOR (EA1 CONNECTOR - ECM)

(a) Disconnect the EA1 connector.

(b) Disconnect the E10 ECM connector.

(c) Measure the resistance according to the value(s) in the table below.

Standard resistance:

(d) Reconnect the EA1 connector.

(e) Reconnect the ECM connector.

3 INSPECT ECM

 INSPECT ECM

(a) Disconnect the E10 ECM connector.

(b) Turn the ignition switch to the ON position.

(c) Measure the voltage according to the value(s) in the table below.

Standard voltage

d) Reconnect the ECM connector.

NOTICE: Fault may be intermittent. Check the wire harness and connectors carefully and retest.

CHECK FOR INTERMITTENT PROBLEMS

4 INSPECT KNOCK SENSOR

INSPECT KNOCK SENSOR

(a) Disconnect the EA1 connector.

(b) Measure the resistance according to the value(s) in the table below.

Standard resistance

(c) Reconnect the EA1 connector.

5 CHECK HARNESS AND CONNECTOR (EA1 CONNECTOR - KNOCK SENSOR)

CHECK HARNESS AND CONNECTOR (EA1 CONNECTOR - KNOCK SENSOR)

HINT:

(a) Disconnect the EA1 connector.

(b) Disconnect the K6 and K5 knock sensor connectors.

(c) Measure the resistance according to the value(s) in the table below.

Standard resistance:

(d) Reconnect the EA1 connector.

(e) Reconnect the knock sensor connector.

REPLACE KNOCK SENSOR (See page ES-520)

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