Hardware:
This GM / Siemens Fuel Composition Sensor(FCS) current: GM12570260 EOL sensor: 12570250 or Continental SE1004S
Hard to find connector available here: [HU Webshop Ethanol Sensor Connector]
or: [US Webshop Ethanol Sensor Connector]
And a how-to on setting up display in VemsTune is available: [VemsTune FlexFuel Setup Guide]
Sensor reads in Hz.
Basic sensor testing:
- Freq stability check:
- Freq. vs input voltage changes:
- 5.5 VDC power supply, Freq. = 69.99 Hz raised up the power supply voltage in 1 volt steps to 16.0 VDC power supply, Freq. = 69.99 Hz
Note, sensor stops operating below 5.5 VDC. 16 VDC was the upper end of testing.
- Current draw at power supply voltages from 5.5 VDC to 16 VDC:
- 25.7 ma to 25.9 ma or .026 amps!
- Connections on sensor:
- Black is GROUND (Ohm to chassis to prove).
- Pink is 12VDC. (car battery, switched with ignition)
- White is the output signal. (A pull up resistor is needed here because the output is an open collector transistor inside the sensor so any voltage interface will work)
| Hz | gasoline | Ethanol | Wheel Speed Reading km/h |
| 50 | 100 | 0 | 50 |
| 55 | 95 | 5 | 55 |
| 60 - E10 | 90 | 10 | 60 |
| 65 | 85 | 15 | 65 |
| 70 | 80 | 20 | 70 |
| 75 | 75 | 25 | 75 |
| 80 | 70 | 30 | 80 |
| 85 | 65 | 35 | 85 |
| 90 | 60 | 40 | 90 |
| 95 | 55 | 45 | 95 |
| 100 | 50 | 50 | 100 |
| 105 | 45 | 55 | 105 |
| 110 | 40 | 60 | 110 |
| 115 | 35 | 65 | 115 |
| 120 | 30 | 70 | 120 |
| 125 | 25 | 75 | 125 |
| 130 | 20 | 80 | 130 |
| 135 - E85 | 15 | 85 | 135 |
| 140 | 10 | 90 | 140 |
| 145 - E95 | 05 | 95 | 145 |
| 150 | 00 | 100 | 150 |
- 50hz is 0.5v, 150hz is 4.5v 0-100% ethanol
- and the pulsewidth of the input is the temperature of the fuel.
- temp formula is ?C = (41.25 * pulsewidth_in_ms) - 81.25
170Hz is error output (self diagnostics built into sensor)