The steering wheel controls (or stalks) for E12 Corolla are quite confusing. There was a generation shift around 2004-2005, where they changed from a serial bus-based interface to a resistor network interface. I don't know the exact reason for the change, but common sense tells me that it simplifies the circuit, thus avoiding possible faults through the chain of events. Resistor networks has also been a automotive standard for many years, so Toyota might have realized that they had to walk the s