Very often, we get tech inquiries about problems that arise after an AmpPRO is installed. However, 99% of the time, the AmpPRO isn't the problem at all. Realistically, an AmpPRO is a very simple device that does not interfere with the vehicle's infotainment data bus at all. To break it down a bit further, the AmpPRO does these things.
- It takes the fixed level, two-channel audio signal that goes from the factory radio to the factory amplifier, sends it through a DSP chip to clean it up, and then provides a variable Front, Rear, and Non-Fading output to easily feed aftermarket amps.
- Alternatively, you can also use the APA-TOS1 to acquire a purely digital TOSLINK output, or as most call it, "Fiber Optic". When using this type of output, the AmpPRO's DSP chip converts the analog audio signal to digital. The digital audio signal coming out is 48khz 24-bit.
- It "listens" to the vehicle's infotainment data bus for the following commands:
- Volume +/- adjustments
- Bass/Mid/Treble audio adjustments
- Balance/Fader adjustments
That's it! Of course, there are a couple of exceptions I will detail below, but as you can see, the AmpPRO is not intrusive at all to the vehicle's infotainment system.
- AP4-FD31 - Instead of tapping into a two-channel fixed-level audio signal, these AmpPROs extract the audio from the data bus. These AmpPROs come equipped with an APA-TOS1, as the audio signal it is tapped into is already digital.
- AP4-CH41 - When used in vehicles that are not equipped with a factory amplifier, and DIP switch 4 is set to the On (down) position, the AmpPRO "tricks" the radio into thinking that there is a factory amplifier present, therefore making it behave as such. This AmpPRO is the only one that actually does any filtering of the vehicle's infotainment bus. That does not imply, however, that this AmpPRO is any more complex or intrusive than the others. It simply transits one small ID to the radio to make the flip.
AmpPRO information
- When designing the AmpPRO, we try to retain the factory amplifier, but this is not always possible. In applications where the factory amplifier can be retained, both the aftermarket amplifier and the factory amplifier can be used. Take note that the aftermarket amplifier will be slightly delayed compared to the factory amplifier. For this reason, it is not recommended to mix and match front speakers with aftermarket and factory, nor to use a processor with time alignment. The AmpPRO amp bypass harness, the APH line, is designed with this in mind and includes connectors for both the factory amp and factory speakers.
- Applications where the factory amplifier cannot be retained:
- AP4-FD31
- Due to the factory amplifier being removed, this AmpPRO includes an amplifier bypass harness.
AmpPRO DIP Switch information
- DIP Switch 1 – This DIP Switch enables 2-channel audio for chime signals. It redirects the rear chimes to the front channels. This is useful for applications that are using the optical output, or just a front-stage system.
- DIP Switch 2 – This dip switch drops the audio signal output voltage down to 4V. This is useful for aftermarket amplifiers that cannot handle a 5V audio signal.
- DIP Switch 3 – This dip switch is product-specific. Refer to the instruction manual for more details.
- DIP Switch 4 – This dip switch is product-specific. Refer to the instruction manual for more details.
AmpPRO Known Issues and Troubleshooting
Known Issue
As of the date this article was written, there is only ONE "known issue" with the AmpPRO line.
- The pins, which are located in the white harness that connects to the AmpPRO interface module, sometimes become dislodged and back out. How to tell if you are having this issue is outlined in detail in this article.
Troubleshooting
If you feel you are having an issue with your factory system that is attributed to the AmpPRO, here are a few things you can do to eliminate the AmpPRO as the source of the problem.
All AmpPRO's
- Is the vehicle factory amplified? The AmpPROs only work with factory-amplified vehicles, aside from the AP4-CH41.
- Is the factory amplifier compatible with the AmpPRO? Refer to the AmpPRO's product page under Compatibility Notes (PAC-Audio website only).
- Is the vehicle on the Fitment Guide? Only vehicles validated by PAC should be used.
- Does the LED on the AmpPRO flicker when you roll the volume knob on the radio? If not, the AmpPRO is not communicating with the factory amplifier.
- Is the factory amplifier plugged in? In all AmpPRO applications aside from the AP4-FD31, the factory amplifier must be plugged in.
- Does the factory amplifier work? If the factory amplifier is not working, the AmpPRO will not work either. The AmpPRO is not a factory amplifier replacement aside from the AP4-FD31 application.
- Is the LED on the AmpPRO off with the key cycled on?
- Is the fuse blown?
- Are any of the pins backed out? Refer to Known Issues for more information.
- Was the ground for the aftermarket amplifier removed (or loose) while the AmpPro was connected and powered up? If so, the AmpPRO may be damaged due to a ground surge through the AmpPRO.
AP4-CH41
- Is the factory radio turning on?
- If yes, proceed to the next step.
- If not, please refer to this article about the loose pins.
- Does the red LED on the AmpPRO blink rapidly when you roll the volume knob on the factory radio?
- If yes, then further troubleshooting with assistance from our tech department may be needed.
- If not, is the vehicle factory amplified, and is the factory amp still in the vehicle and connected?
- If using the AP4-CH41 in a non-amplified vehicle, did you program the AmpPRO interface as outlined in the instruction manual?
- If yes, try a second or third time, with the vehicle running.
- If no, please do so.
- This article explains how to program the AP4-CH41.
AP4-FD31 - No audio.
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Does the radio display No Audio? Is the volume indicator on the radio not working? This indicates the radio isn't communicating with the AmpPRO. Inspect the blue A2B connector to ensure it is seated all the way in.
Note: With the factory amplifier removed, the radio will default to show Surround On. However, the surround sound feature will not be on.
If you’ve completed this troubleshooting and still have issues, please contact our technical support team and be ready to run some tests.
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