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

If you hear music from all of the speakers but not when faded to the front, that indicates the AP4-CH41 interface wasn’t programmed or the programming didn't take. Follow these steps to program the interface.

1. 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.
2. Dip switch four should be set in the on position. If it is not, the interface must be unplugged and dip switch four set to on.
3. Start the vehicle and wait for the radio to load up. The interface should have a solid red light indicating it is on.
4. Press and hold the programming button on the interface until the LED turns amber, then immediately let go. The radio will briefly turn off and then back on.
5. Repeat step 4.
6. Check the fader to ensure it is functioning properly.