Code 43, Electronic Spark Control - ESC

Code 43 indicates that the ECM has seen low voltage at circuit 457 for longer than 4 seconds with the engine running. This voltage drops when ESC module shuts off because it receives a knock signal.

NOTE: The following step numbers refer to the numbers in the accompanying flow chart(s).

This test checks if ECM recognizes a problem.
The ESC module supplies voltage to the ECM. It should always be over 6 volts unless the system is sensing engine detonation.
This test checks for intermittent ESC operation. If the voltage is now over 6 volts, it is faulty ESC terminal C connection or ESC module.
This test checks for grounded ECM.
This test checks open ignition circuit.

Fig 1: Code 43, Electronic Spark Control - ESC