Code 43, Electronic Spark Control (5.0L & 5.7L)

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

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

Fig 1: Code 43, Electronic Spark Control (5.0L & 5.7L)

Fig 2: Code 43 Schematic, (5.0L & 5.7L)