DTC 43

Chart - Code 43 Electronic Spark Control Circuit:

Wiring Diagram for Electronic Spark Control.:

CODE 43 - ELECTRONIC SPARK CONTROL (ESC) CIRCUIT



Circuit Description:

The knock sensor is used to detect engine detonation and the electronic control module (ECM) will retard the electronic spark timing based on the signal being received. The circuitry within the knock sensor causes the ECM 5 volts 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. If CKT 496 becomes open or shorted to ground, the voltage will either go above 3.5 volts or below 1.5 volts. If either of these conditions are met for about 5 seconds a Code 43 will be stored.


Test Description: Numbers below refer to circled numbers on the diagnostic chart.
1. If the conditions for testing are being met a code 43 will be set and the "SERVICE ENGINE SOON" light will be on.
2. The ECM has a 5 volt signal throgh a pull up resistor and should be present at the knock sensor terminal.
3. Checks the internal resistance of the knock sensor.



Diagnostic Aids:
Check CKT 496 for a potential open or short to ground.
Check for proper installation of Mem-Cal.
Refer to "DIAGNOSIS BY SYMPTOMS - TROUBLE CODE STORED".
Mechanical engine problems can cause knock sensor signal and must be repaired before using this chart.