DTC 43

Code 43 Chart:

Knock Sensor Circuit:

CIRCUIT DESCRIPTION
The knock sensor is used to detect engine detonation and the PCM will retard the electronic spark timing based on the signal being received. The circuitry within the knock sensor causes the PCM's supplied 5 volt signal to be pulled down, so that under a no knock condition CKT 496 would measure about 2.5 volts.

The knock sensor produces an AC signal which rides on the 2.5 volts DC voltage. The amplitude and signal frequency is dependent upon the knock level.

Code 43 will set if:
^ CKT 496 voltage will go above 3.5 volts (open or shorted to ground)
OR
^ CKT 496 voltage will go below 1.5 volts. (shorted to ground)
^ Either of the above conditions are met for 20 seconds.


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


1. If a Code 43 is detected, the PCM will retard spark timing by 10 degrees. If an audible knock is heard from the engine, repair the internal engine problem. Normally no knock should be detected at idle.

2. The PCM applies 5 volts to CKT 496, which should be present at the knock sensor terminal.

3. This test determines if the knock sensor is faulty or if the knock sensor portion of the PROM is faulty.


DIAGNOSTIC AIDS:
Check CKT 496 for a intermittent open or short to ground. Also check for proper installation of PROM. If knock sensor circuit 496 is routed to close to secondary ignition wires, it may induce a voltage and cause a false knock signal.