Code 43 - Electronic Spark Control (ESC)

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. This test will determine if the system is functioning at this time. The knock sensor should respond if exhaust manifold is tapped above sensor.
3. The ESC module supplies voltage to the ECM. It should always be over 6 volts unless the system is sensing engine detonation.
4. 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.
5. This test checks for grounded ECM.
6. This test checks for open ignition circuit.

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

Fig 2: Flow Chart, Code 43: Electronic Spark Control (All Engines)

Fig 3: Schematic, Code 43: Electronic Spark Control (All Engines)