Code 43 - Electronic Spark Control

Code 43 indicates the ECM has seen low voltage at circuit 457, terminal "B7" in the ECM "AB" connector for longer than 4 seconds with the engine running. This voltage drops when the ESC module shuts off because it receives a knock signal.

1. The ESC module supplies voltage to the ECM. It should always be over 6 volts unless the system is sensing engine detonation.
2. 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.

Fig 1: Code 43, Electronic Spark Control

Fig 2: Code 43, Electronic Spark Control