AP4-CH41 & AP4-CH42: Fader not working in a non-amplified vehicle

If you hear music from all speakers except when faded to the front, the AP4-CH41 interface wasn’t programmed, or the programming failed. Follow these steps to program it.

Requirements

• For the AP4-CH41 only, ensure the interface has the latest firmware version. A sticker on the interface indicates the firmware. For Version 2, V16 is the latest firmware. For Version 3, 3.2.5.3 is the latest firmware as of this writing.
• DIP switch 4 should be set in the on position. If it is not, the module must be unplugged and DIP switch 4 set to on.

Programming

• Start the vehicle and wait for the radio to load up. The interface should have a solid Red light indicating it is on.
• Press and hold the programming button on the interface until the LED turns Orange, then immediately let go. The radio will briefly turn off and then back on.
• Repeat step 4.

Testing

• Check the fader to ensure it is functioning properly.