Powertrain Controls - ECM/PCM

Code 43 Diagnostic Chart:

Knock Sensor Circuit Schematic:

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.

DTC 43 WILL SET WHEN
^ If there is an indication of knock for more than 4.54 seconds over a 5 second interval with the engine running.
^ If PCM terminal "BC13" does not indicate increasing Knock Sensor (KS) activity with engine speed.

ACTION TAKEN (PCM WILL DEFAULT TO)
Malfunction Indicator Lamp (MIL) illuminates.

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 being met, DTC 43 will be currently set and the MIL (Service Engine Soon) 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 35-50 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.
5. Check the knock sensor connections for loose terminals or corrosion. A faulty connection will set a DTC 43. If connections are OK, a faulty component will also set a DTC 43.

DIAGNOSTIC AIDS
^ Check CKT 496 for a potential open or short to ground. Also check for proper installation of the EPROM.
^ An "Intermittent" problem may be caused by a poor connection, rubbed through wire insulation, or a wire that is broken inside the insulation. Any circuitry, that is suspected as causing the intermittent complaint, should be thoroughly checked for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, poor terminal to wiring connections or physical damage to the wiring harness.
^ Refer to "DIAGNOSIS BY SYMPTOM/INTERMITTENTS". - Intermittent Malfunctions
^ A mechanical engine knock can cause a knock sensor signal. Abnormal engine noise must be corrected before using this chart.