Eric Page
11-06-2020, 09:18 AM
The following post appeared yesterday on the AeroElectric-List forum, and I thought that it might help someone here. It appears that the Kitfox factory mistakenly shipped incorrect resistor values with a 912iS installation kit. Since they probably purchased the resistors in bulk, this may not be an isolated problem.
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The Rotax 912iS lane LED lights did not work in my friend's Kitfox. There was a faint flicker when the lane switches were first turned on. The lights worked fine when a 9 volt battery was connected to the pins in the HIC connector for the lights. So the problem must be in the Rotax harness or CPU or fuse box, right?
NO
After days of troubleshooting, we decided to remove the LED parallel resistor to see if that made a difference. Wow, that did it. The LED lane lights now worked. It turns out that the Kitfox supplied resistors were 1R5 (1.5 ohms), not the recommended 1K5 (1500 ohms). The purpose of those parallel resistors is to prevent the LEDs from glowing dimly when the Rotax solid state switch is off. A 9 volt battery has enough current capacity to power both a low value resistor and a LED. But the Rotax CPU must have internal resistance that limits the current.
Lesson learned: Check load resistance.
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>>>
The Rotax 912iS lane LED lights did not work in my friend's Kitfox. There was a faint flicker when the lane switches were first turned on. The lights worked fine when a 9 volt battery was connected to the pins in the HIC connector for the lights. So the problem must be in the Rotax harness or CPU or fuse box, right?
NO
After days of troubleshooting, we decided to remove the LED parallel resistor to see if that made a difference. Wow, that did it. The LED lane lights now worked. It turns out that the Kitfox supplied resistors were 1R5 (1.5 ohms), not the recommended 1K5 (1500 ohms). The purpose of those parallel resistors is to prevent the LEDs from glowing dimly when the Rotax solid state switch is off. A 9 volt battery has enough current capacity to power both a low value resistor and a LED. But the Rotax CPU must have internal resistance that limits the current.
Lesson learned: Check load resistance.
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