AEM 30-71XX Infinity Stand-Alone Programmable Engine Mangement System Full Manual - Manual (Page 244)

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© 2014 AEM Performance Electronics
Infinity User Manual
Flex Fuel FCS Plumbing
The FCS should be plumbed into the system, preferably before the fuel injectors. It consists of
5/16" and 3/8" quick disconnect fittings. The internal microprocessor of the FCS outputs a
varying digital square wave frequency and pulse width. The AEM Infinity decodes this input and
displays a flex fuel content percentage and fuel temperature.
Flex Fuel FCS Wiring
There are 3 wiring terminals on the GM FCS. Pin A is Ground and should be connected to a
clean chassis ground. Pin B is +12V and should be connected to a 12V ignition switch source.
Pin C is the digital output signal and should be wired to AEM Infinity Pin C1-26 (Digital_In_5).
Flex Fuel FCS Output
The frequency of the signal indicates the ethanol percentage. The output frequency is linear with
respect to the percentage of ethanol content in the fuel. The fuel composition sensor normally
operates between 50-150Hz, where 50Hz represents 0% ethanol and 150Hz represents 100%
ethanol. If the output frequency goes up to 170Hz, the sensor has gone into a fail safe mode as it
has indicated a fuel contamination such as methanol, water, salt, etc. The pulse width indicates
the fuel temperature and normally operates between 1-5mS where 1mS indicates -40°C (-40°F)
and 5mS indicates 125°C (257°F).
Infinity Tuner Flex Fuel Tables
FlexContent