MN C5
April 22nd, 2006, 09:45 AM
From the GMTech site
Flexible Fuel
Sensor
To measure the true ethanol alcohol percent-age and fuel temperature needed for proper engine operation, the L43 engine uses a flexi-ble fuel sensor. It's located on the top of the right side frame rail, behind the right front upper control arm. All fuel delivered to the engine passes through the flex fuel sensor forethanol measurement.Here's how the sensor determines alco-hol percentage and fuel temperature. Thesensor generates a digital signal that varies infrequency, based on ethanol percentage. By
measuring the frequency of the signal, thePCM can determine the ethanol percentage.A 50 Hz signal equals a zero percentage of ethanol. If a true E100 ethanol fuel (100 per-cent ethanol) was available, it would equal150 Hz. So an E85 fuel containing 85 percent ethanol should be about 135 Hz.The sensor controls the width of the digital signal (pulsewidth) to indicate fuel temperature. The sensor causes its output signal pulsewidth to be between 1 millisecond(equals a fuel temperature of -40 degrees
Celsius) to 5 milliseconds (equals a fuel temperature of 125 degrees Celsius).The flex fuel sensor has its own internal circuit diagnostic capabilities. If an internal sensor fault is detected, the output will be forced to 170 Hz if the fault is with the percentage-measuring circuits. Output will be forced to 0.5 millisecond pulsewidth and 170Hz if the fault is with the temperature-measuring circuits.
Flexible Fuel
Sensor
To measure the true ethanol alcohol percent-age and fuel temperature needed for proper engine operation, the L43 engine uses a flexi-ble fuel sensor. It's located on the top of the right side frame rail, behind the right front upper control arm. All fuel delivered to the engine passes through the flex fuel sensor forethanol measurement.Here's how the sensor determines alco-hol percentage and fuel temperature. Thesensor generates a digital signal that varies infrequency, based on ethanol percentage. By
measuring the frequency of the signal, thePCM can determine the ethanol percentage.A 50 Hz signal equals a zero percentage of ethanol. If a true E100 ethanol fuel (100 per-cent ethanol) was available, it would equal150 Hz. So an E85 fuel containing 85 percent ethanol should be about 135 Hz.The sensor controls the width of the digital signal (pulsewidth) to indicate fuel temperature. The sensor causes its output signal pulsewidth to be between 1 millisecond(equals a fuel temperature of -40 degrees
Celsius) to 5 milliseconds (equals a fuel temperature of 125 degrees Celsius).The flex fuel sensor has its own internal circuit diagnostic capabilities. If an internal sensor fault is detected, the output will be forced to 170 Hz if the fault is with the percentage-measuring circuits. Output will be forced to 0.5 millisecond pulsewidth and 170Hz if the fault is with the temperature-measuring circuits.