The ECU must be sensing too much current or seeing the directionals as an open circuit; if you have a GS-911 OBD-II tool, you can troubleshoot this fairly easy. If not equipped with a GS-911, and if you have a VOM (Volt Ohm Multi Meter); you can measure the bulbs resistance value and or measure the actual amperage draw within the circuit for each of the two different types of lights.
The GS-911 tool allows you to see live parameters as reported from the body controller; for example, you can temporarily install the original directionals back on the bike, and record the current draw (Amperage) for the lights in question via the GS-911.
Next, install the cheap ass eBay lights and note the amperage as reported within the GS-911 platform; this will give you an idea of the difference, where you might be able to add a resistor in order to match the resistance of the OEM directionals. Using Ohm's law, you can easily solve for the resistance value and come up with a resistive circuit in order to try and match what the ECU is looking for as an acceptable amperage draw (either adding a resistor in series, or perhaps a parallel circuit design).
Also, the GS-911 allows for the selection between LED (Light Emitting Diode) and Incandescent type lights, the solution might be as easy as changing the bulb type?
In short (no pun intended), try and get some measurements and report back, we can assist in walking you through it; you're going to need either of the above mentioned tools to try and troubleshoot this issue - unless someone has already figured this out...
