Understanding the wiring diagram for steering wheel control keys, specifically Key 1 and Key 2 wires, is crucial for troubleshooting common issues with aftermarket head units. This article addresses a specific problem with a Joying/Funrover head unit installed in a 2012 Ford Focus Titanium, where steering wheel control buttons register incorrect resistance values.
The issue stems from a mismatch between the resistance values expected by the head unit and those sent by the steering wheel control module. The Joying head unit’s built-in steering wheel control app shows default resistance values around 30 ohms. When a button is pressed, this value only changes slightly to around 16 or 20 ohms. However, the head unit manual indicates significantly higher base resistance values, starting at 256 ohms. This discrepancy prevents the head unit from correctly interpreting button presses.
Direct measurements of the car’s steering wheel control wires using a multimeter confirm that the car is sending the correct resistance signals, ranging from 250 to 1500 ohms. This eliminates the car’s wiring as the source of the problem.
Further attempts to troubleshoot the issue involved simulating the steering wheel buttons using an Arduino with resistors. Even with this controlled setup, it was impossible to get the head unit to register resistance values above 30 ohms, regardless of whether Key 1 or Key 2 wire was used. Additionally, an external SWC interface designed to amplify resistance signals did not resolve the problem.
Changing the car model settings within the head unit’s menu to different manufacturers like RZX or VW had some impact, suggesting a potential configuration issue. However, achieving the expected base resistance level of 256 ohms remains elusive. The initial resistance of 30 ohms persists even without the Key and Ground wires connected.
The core problem appears to lie in a fundamental impedance mismatch between the Joying head unit and the Ford Focus steering wheel control system. A potential solution may involve modifying the head unit’s input impedance, but this requires further investigation. This case highlights the complexities of integrating aftermarket head units with factory steering wheel controls and underscores the importance of understanding the “Diagram Steering Wheel Control Key 1 Key 2 Wires” for successful installation and troubleshooting. The search continues for a solution to this impedance mismatch, focusing on potential modifications to the head unit or alternative interface solutions.
