Powertrain Controls - ECM/PCM

DTC 43 Knock Sensor (KS) Circuit:

Knock Sensor (KS) Circuit:

CIRCUIT DESCRIPTION
The knock sensor (KS) detects engine detonation and the Powertrain Control Module (PCM) retards the electronic spark timing based on the signal being received. The knock sensor produces an AC signal which is used for knock detection. The amplitude and signal frequency are dependent upon the knock level.

DIAGNOSTIC TROUBLE CODE (DTC) 43 WILL SET WHEN
^ Engine Coolant Temperature (ECT) is above 56° C (133° F).
^ Throttle Position (TP) angle is above 4.7%.
^ Engine speed is between 2200 and 6375 RPM.
^ There is an indication of knock for more than 4 seconds over a 6 second interval.
^ Knock sensor activity does not increase with engine speed.

ACTION TAKEN (PCM WILL DEFAULT TO)
The Malfunction Indicator Lamp (MIL) will illuminate, ignition timing will default to 3.95 degrees BTC, and the cooling fan will enable.

DTC CHART TEST DESCRIPTION
Number(s) below refer to circled number(s) on the diagnostic chart.

1. If the conditions for the test as described above are met, DTC 43 will set and the MIL (Check Engine) will be illuminated.
2. If the engines has an internal problem which is creating a knock, the knock sensor may be responding to the mechanical noise.
3. The Tech 1 scan tool displays knock sensor activity in counts, approximately 50 at idle. The counts should rise when engine speed increases or fall when engine speed decreases. This step checks knock sensor activity
4. This step checks that the internal resistance of knock sensor is within an acceptable range. Use breakout box overlay I 39700-112.Refer to PCM terminal end view.
5. Check the knock sensor connection for loose terminal or corrosion. A faulty connection will set a DTC 43.

DIAGNOSTIC AIDS
^ An intermittent problem may be caused by a poor connection, rubbed through wire insulation, or a wire that is broken inside the insulation.
^ Any circuit that is suspected of causing the intermittent complaint should be thoroughly checked for improper mating, broken locks, improperly formed or damaged terminals, poor wiring connections or physical damage to the wiring harness.
^ Mechanical engine knock can also cause a knock sensor signal. Abnormal engine noise must be corrected before using this chart.
^ Refer to "Intermittents," in Diagnosis by Symptom. - Intermittent Malfunctions