GM 3.3L 204 CI V6 VIN: N Information Database






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		*OBD I Fault Code Detail*

	*Code 42* *Electronic Spark Timing (EST) Circuit*

	The C3I module sends a reference signal to the ECM when the engine is cranking. Under 400 rpm, the C3I module controls ignition timing. When the engine speed exceeds 400 rpm, the ECM sends a 5 volt signal on the bypass circuit to switch timing to ECM control. In an open or ground occurs while the engine is running in EST mode, the engine will stall and set a Code 42. If the bypass circuit is open or grounded while the engine is cranking, the engine will start and remain in backup. To set a code 42, the following conditions must be met: - Engine speed is greater than 600 rpm with no EST pulse for more than 200 microseconds or - ECM commanding bypass mode



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