Code 43 - Electronic Spark Control (ESC)
Code 43 indicates that the Electronic Spark Control (ESC) retard signal has been seen by the ECM for too long a period of time. When voltage at term. "L" at the ECM is low, spark is retarded. Normal voltage in non-retard mode is about 7.5 volts or more.
NOTE:
The following step numbers refer to the numbers in the accompanying flow chart(s).
- Normal voltage would be over 7.5 volts. If 7.5 volts is present at term. "L", the reason for a Code 43 is a poor connection to ECM or faulty ECM.
- Over 6 volts indicates an overly sensitive knock sensor or controller, or noise in the engine that triggers knock sensor.
- This test checks for grounded ECM.
- This test checks for an open in wire from ESC to ECM. If over 6 volts was obtained at term. "C" of the ESC, the fault is an open to term. "L" of ECM.
- This test checks for 12 volt ignition source to ESC term. "B". Reading at term. "B" should be battery voltage.
- This checks to see if spark retard is due to engine knock or a faulty knock sensor. If by disconnecting the knock sensor spark advances, fault is in engine "noise" or sensor. Normally no increase would be noted.
- This checks to see if spark retard is due to "noise" on ESC to knock sensor line or a faulty ESC controller. By removing terminal "E" from the connector, the determination can be made. If spark advances, check for improper routing of knock sensor signal wire.