Code 43 - Electronic Spark Control (ESC)

Code 43 will set if: ECM has seen low voltage at circuit 485, terminal "B7" in the ECM AB connector, for more than 6 seconds with the engine running.

1. Checks to see if ECM recognizes a problem in circuit 485.
2. Determines if the system is functioning at this time. The knock sensor should respond if the exhaust manifold is tapped above the sensor.
3. The ESC module supplies voltage to the ECM. Voltage should always be above 6 volts unless system is sensing engine detonation.
4. Checks for an intermittent ESC operation. If the voltage reading is now over 6 volts, it's a faulty ESC terminal "C" connection or ESC module.
5. Checks for grounded ECM.
6. Checks for open ignition circuit.

Fig 1: Code 43 Flow Chart, Electronic Spark Control

Fig 2: Code 43 Flow Chart, Electronic Spark Control

Fig 3: Code 43 Schematic, Electronic Spark Control