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Cliff8928 · 10-04-2013, 04:40 AM

2 crank sensors and one cam sensor....

The 7x (3x) is mounted through the rear of the block to a reluctor wheel on the crank itself. This sensor only provides a signal to the Ignition Control Module, the ICM communicates with the PCM. The 24x sensor is mounted behind the harmonic balancer and provides a higher resolution signal to the PCM. The cam sensor is under the power steering pump and is connected to the PCM. The combination of the 24x and cam sensor are what enable the "SFI" to work. The older MFI engines (before 1994) only had the 7x sensor for everything.

I don't recall if the PCM will have a fail-safe if the 24x sensor fails. If the 7x sensor fails, I'm 99.9% sure it's not going to run.

They all can affect driveability.

10-04-2013, 04:40 AM	#5
Cliff8928 Moderator Join Date: Nov 2004 Location: Long Grove, IL Posts: 5,002	2 crank sensors and one cam sensor.... The 7x (3x) is mounted through the rear of the block to a reluctor wheel on the crank itself. This sensor only provides a signal to the Ignition Control Module, the ICM communicates with the PCM. The 24x sensor is mounted behind the harmonic balancer and provides a higher resolution signal to the PCM. The cam sensor is under the power steering pump and is connected to the PCM. The combination of the 24x and cam sensor are what enable the "SFI" to work. The older MFI engines (before 1994) only had the 7x sensor for everything. I don't recall if the PCM will have a fail-safe if the 24x sensor fails. If the 7x sensor fails, I'm 99.9% sure it's not going to run. They all can affect driveability. __________________ Cliff Scott 2004 Alero GX w/sport pkg - Sold, living somewhere in WI now. 2011 Saab 9-5 Turbo4 M6 2004 Corvette Convertible M6 1994 Chevy Beretta - Quad4/M5