Pioneer AVH & DMH Series Steering Wheel Control Issues
Problem Description
Some Pioneer AVH and DMH series radios, including models like DMH-A240BT, DMH-A340DAB, and early SPH-DA160 models, have been sold with older firmware that is incompatible with steering wheel controls (SWC). This can result in the steering wheel buttons not functioning correctly.
Troubleshooting Steps
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Check Firmware Version
To verify your radio's firmware version, navigate to the 'Settings' menu and then to the 'System Information' screen. The correct firmware version required for SWC compatibility is MCU version 1.49.
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Update Firmware
If your radio has an earlier firmware version, please contact Pioneer Support at 0208 836 3500 (select option 1) to obtain the firmware update. This update may not be available online.
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End Call Button Issue
Even after a successful firmware update, the 'end call' button on the steering wheel may still not function. There is currently no known fix for this specific issue.
Alternative Solution: Diode Modification
If updating the firmware is not possible, a diode can be added to the patch lead to enable SWC functionality. Please note that this method may not work for all vehicles, and in many cases, no steering wheel buttons will function when using this workaround.
Recommended Part: Instead of the standard 29-007 or 29-025 universal patch leads, a 29-007D patch lead with a built-in blocking diode is recommended. This is a special-order item and may require a short delay for manufacturing.
DIY Diode Installation: If you have a 29-007 or 29-025 patch lead and need an immediate solution, you can install a diode (tested with IN4002) to the red wire of the 3.5mm jack. The cathode of the diode should be positioned closest to the steering wheel control box. This connection should be made between pin 3 and the center pin of the 3.5mm jack.
The diagram shows a 3.5mm jack with three sections: Tip, Middle, and Bottom. The Tip is connected to a white wire. The Middle section is connected via a red wire to the anode of a diode labeled 'IN4002'. The cathode of the diode is connected to a black wire, which then connects to pin 3 of a connector block (pins labeled 1-12). Pin 5 of the connector block is also shown.
