Electronic Control System Gas Plus Engines – 019-392   Knock Sensor Circuit

NOTE: The sensor does
not have any testable limits for resistance. If you suspect a bad sensor, exchange the positions of the two knock sensors and check to see if the fault has “followed” the sensor.

Disconnect engine harness ECM connector 2 from the ECM. Disconnect the knock sensor from the engine harness. Set the multimeter to measure resistance.

Measure the resistance from the knock (+) pin in engine harness ECM connector 2 to the corresponding pin in the engine harness sensor connector.

The multimeter
must show a closed circuit (10 ohms or less).

If the circuit is
not closed, there is an open circuit in the signal wire.

Repair or replace the engine harness. Refer to Procedure
019-214,
019-204, or
019-043.

Measure the resistance from the knock (-) return pin in engine harness ECM connector 2 to the corresponding pin in the engine harness sensor connector.

The multimeter
must show a closed circuit (10 ohms or less).

If the circuit is
not closed, there is an open circuit in the return wire. Repair or replace the engine harness. Refer to Procedure
019-214,
019-204, or
019-043.

Disconnect engine harness ECM connector 2 from the ECM. Disconnect the knock sensor from the engine harness. Set the multimeter to measure resistance.

Measure the resistance from the knock (-) pin in engine harness ECM connector 2 to engine block ground.

The multimeter
must show an open circuit (100k ohms or more).

If the circuit is
not open, there is a short circuit to ground in the return wire.

Repair or replace the engine harness. Refer to Procedure
019-204, or
019-043.

Measure the resistance from the knock (+) pin in engine harness ECM connector 2 to engine block ground.

The multimeter
must show an open circuit (100k ohms or more).

If the circuit is
not open, there is a short circuit to ground in the signal wire. Repair or replace the engine harness. Refer to Procedure
019-204, or
019-043.

Disconnect engine harness ECM connector 1 and connector 2 from the ECM. Disconnect the knock sensor from the engine harness. Set the multimeter to measure resistance.

Measure the resistance from the knock (+) pin in engine harness ECM connector 2 to all other pins in the connector and to all pins in engine harness ECM connector 1.

The multimeter
must show an open circuit at all pins.

If any pin-to-pin check does
not show an open circuit, there is a short circuit between the applicable pins.

Repair or replace the engine harness. Refer to Procedure
019-204, or
019-043.