Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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HOMESERVICE MANUALSCHEVROLET1990CAVALIER BASE, 4D SEDAN, AUTOMATIC, 125C/MD9REPAIR AND DIAGNOSISENGINE PERFORMANCESYSTEMENGINE CONTROLS - TESTS W/CODES - 2.2L TBIDIAGNOSTIC CODESCODE 43, ELECT SPARK CONTROL SIGNAL VOLT LOWNOTES
1990 Chevrolet Cavalier Base, 4D Sedan, Automatic, 125C/MD9
Code 43, Elect Spark Control Signal Volt Low: Notes
1990 Chevrolet Cavalier Base, 4D Sedan, Automatic, 125C/MD9SECTION Notes
- If conditions for a Code 43 exist, "Scan" tester will display "YES". There should not be a knock signal at idle unless an internal or system problem exists.
- Determines if system is functioning at this time. Usually, a knock signal can be generated by tapping on the exhaust manifold. If no knock signal is generated, try tapping on engine block closer to sensor.
- Because Code 43 sets when the signal voltage on the spark retard line remains low, this test should cause the signal on that line to go high. The 12-volt signal should be seen by the ECM as a "no knock" signal if the ECM and wiring are okay.
- This test will determine if the knock signal is being detected on the sensor-to-controller line or if the ESC module is at fault.
- If sensor line is routed too close to secondary ignition wires, the ESC module may see the interference as a knock signal.
- This checks ground circuit to module. An open ground will cause the voltage on the monitored line to be about 12 volts. This would cause the Code 43 functional test to fail.
- Contacting the sensor-to-controller wire with a test light connected to 12 volts will generate a knock signal to the controller. This will determine if the ESC controller is operating correctly.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.