Electronic Spark Control (ESC) System Check

Electronic Spark Control system Check:

Wiring Diagram For Electronic Spark Control system Check:

ELECTRONIC SPARK CONTROL SYSTEM CHECK

CIRCUIT DESCRIPTION:

The code 43 circuit consist of a knock sensor with one wire that goes directly to the PCM. There are two code 43 checks performed by the PCM. One check consist of monitoring CKT 496 for a voltage that is more than .04 volt and less than 4.6 volts.

If voltage is either too high or too low for 16 seconds or more, code 43 will set. Once engine temperature reaches 87.5~C or more but not over 104~C, and MAP is 81 kPa and engine speed is 3200 rpm respectively, the PCM will perform a self check by advancing the timing incrementally while anticipating a knock sensor signal. If no knock signal is received during two consecutive test, code 43 will set.



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

1. The first test is to determine if the system is functioning at the present time.

2. Test two determines the state of the 5 volt reference voltage applied to the knock sensor circuit.


DIAGNOSTIC AIDS:

^ The PCM applies 5 volts to CKT 496. A 3500 ohm resistor in the knock sensor reduces the voltage to about 2.5 volts. When knock occurs, the knock sensors produces a small AC voltage that rides on top of the 2.5 volts already applied. An AC voltage monitor in the PCM, is able to read this signal as a knock and incrementally retards spark.