Powertrain Controls - ECM/PCM

Trouble Code 43 Chart:

Knock Sensor Wiring:

CIRCUIT DESCRIPTION
The Knock Sensor (KS) is used to detect engine detonation. The Powertrain Control Module (PCM) receives the knock sensor signal and will retard Ignition Control (IC) timing until knock is not detected. The circuitry within the KS will drop approximately half of the 5 volts applied to the sensor on circuit 496. When engine detonation occurs, the sensor produces an AC signal which rides on the 2.5 volt DC signal. The voltage amplitude and frequency is dependent upon the knock level emitted from the engine combustion process.

DIAGNOSTIC TROUBLE CODE (DTC) 43 WILL SET WHEN
The PCM detects above 4.6 volts or below 0.84 volt for 10 seconds.

ACTION TAKEN (PCM) WILL DEFAULT TO
The Malfunction Indicator Lamp (MIL) will become illuminated. Knock retard will be fixed at 15° of timing retard.

DTC 43 WILL CLEAR WHEN
A current DTC 43 will clear when the PCM senses the signal voltage level between 0.85 and 4.5 volts. A History DTC 43 will clear after 50 consecutive ignition key cycles without a current DTC being stored.

TEST DESCRIPTION
Numbers below refer to circled numbers on the diagnostic chart.

1. If the conditions for DTC 43, as described above, are being met, the Tech 1 scan tool (or equivalent) will always indicate "Yes" when the knock signal position is selected. If an audible knock is heard from the engine, repair the internal engine problem, as normally no knock should be detected at idle.
2. The PCM applies a 5 volt signal to the sensor on circuit 496.

DIAGNOSTIC AIDS
Check circuit 496 for an intermittent open or short to ground. Also, check for proper installation of KS module. If the knock sensor circuit 496 is routed too close to secondary ignition wires, it may induce a voltage and cause a false knock signal.
Refer to Computers and Controls / System Diagnosis / Procedures / Diagnosis by Symptom /Detonation, Spark Knock. Detonation/Spark Knock/Pings