Code 43 - Electronic Spark Control

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

1. This test checks if ECM recognizes a problem.
2. The ESC module supplies voltage to the ECM. It should always be over 6 volts unless the system is sensing engine detonation.
3. 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.
4. This test checks for grounded ECM.
5. This test checks open ignition circuit.

Fig 1: Code 43 Schematic, Electronic Spark Control (All Engines)

Fig 2: Code 43 Chart