AP4-CH42 Advanced Amplifier Interface

Introduction and Features

The AP4-CH42 provides a 6-channel pre-amp output for use with aftermarket audio equipment. Using the full range, fixed level head unit output, in conjunction with CAN messages, the AP4-CH42 delivers a variable 5v RMS pre-amp output with fading, balance, equalization, and level control capabilities. The module also retains all audio from other vehicle features such as factory navigation prompts, Bluetooth, uConnect, and parking sensor chimes. A data controlled remote amplifier turn on wire is also provided by the AP4-CH42. When used in conjunction with the APA-TOS1 (sold separately), the module can provide a variable 2-channel fiber optic digital audio output (TOSLINK).

Important Notes

1. Compatible with both amplified and non-amplified factory systems.
   • Amplified Vehicles: Compatible with all data-bus controlled amplified systems, regardless of screen size (including 12" screen). Identify these systems by looking for logos on door speakers, tweeters, dash speakers, or the subwoofer to confirm if the vehicle has an amplified system (e.g., Alpine & Harmon Kardon). Some vehicles may not always have branded systems. Unbranded amplified systems are generally identified by locating a center channel speaker or subwoofer.
   • Non-Amplified Vehicles:
     • Jeep Wrangler: Compatible with all screen sizes (5", 7" and 8.4").
     • All other models: Only compatible in vehicles equipped with the 7" or 8.4" screen. Vehicles equipped with the 5" screen are not compatible.
   • If you are installing the AmpPRO in a vehicle not equipped with a factory amplifier, you must add an amplifier to the vehicle's speakers, as the factory radio will no longer have a 4-channel variable output after reconfiguration by the AmpPRO. For example, you cannot add only a subwoofer to a non-amplified vehicle, as the radio will no longer power the cabin speakers properly.
   • Non-amplified vehicles equipped with an Active Noise Cancellation (ANC) system require the ANC module to be bypassed. This can be done manually or with the ANC bypass harness ANC-CH01. See page 2, Step 6d for re-configuring the factory radio.
   • If a factory amplifier is present, it must remain connected and in the vehicle after the AmpPRO has been installed.
   • The remote output is rated at 2A of current. If more current is needed, an external relay must be used.
   • Channels 5 and 6 are non-fading outputs. The output level of channels 5 and 6 can be controlled using the supplied level control knob.
   • The chime volume and minimum volume levels are set to 0 dB by default. If you are satisfied with these levels, no additional adjustment is required. Please refer to the Setup and Configuration section on page 2 for more details.
   • The level control knob must be connected to manually adjust the chime volume and minimum volume settings.
   • The factory radio's speed-controlled volume and surround sound mode are not supported by the AP4 outputs.
   • When using the TOSLINK output (APA-TOS1 sold separately), DIP switch 1 must be ON for all warning chimes to be heard through the sound system (see page 2, Step 6a for details).
   • No adjustments can be made manually using the programming button or the factory SWC when the module is connected to a PC.

Module Layout

The AP4-CH42 module features the following connections and indicators:

• Interface Connector 1: Connects to the vehicle's factory harness.
• Expansion Port: For future expansion modules.
• Programming Button: Used for configuration and reset procedures.
• USB Connection: For connecting to a PC for app and firmware updates.
• Feature Select DIP switches: Used to configure various module functions.
• Non-Fading Level Control Knob Connection: Connects the included knob for manual level adjustment.
• TOSLINK Output: Optional fiber optic digital audio output (requires APA-TOS1, sold separately).
• LED 1 & LED 2: Status indicator lights.
• Front Output: RCA outputs for Channels 1 (Left) and 2 (Right).
• Rear Output: RCA outputs for Channels 3 (Left) and 4 (Right).
• Non-Fading Output: RCA outputs for Channels 5 (Left) and 6 (Right).

Installation

Follow these steps to install the AP4-CH42 module:

DIP Switch Configuration:

Set DIP switches to the ON position to activate corresponding features. Set DIP switches to the OFF position for features not desired.

1. Remove the factory radio.
2. Disconnect the main 32 & 12-Pin factory harness from the radio.
3. Connect the AmpPRO harness to the vehicle harness.
4. Connect the AmpPRO harness to the factory radio.
5. If using the AmpPRO in a vehicle with a factory amplifier, leave the "Factory Speaker Connection Point" connectors plugged into each other. If the vehicle has no factory amplifier, connect the aftermarket amplifier's speaker outputs to the provided "Factory Speaker Connection Harness" and connect to the "Factory Speaker Connection Point."
6. Set any feature DIP switches that apply to your installation.
7. If you are using the APA-TOS1 (sold separately), refer to the instructions included with that product for its installation.
8. Connect the AmpPRO harness to the module.
9. Connect the level control knob to the module and install in an accessible location.
10. Connect the signal cables and remote input from the aftermarket amplifier.
11. Complete the "Radio Reset Procedure." (See page 5 for more information)
    • Make sure the radio is fully booted and LED 1 is ON. Press and hold the "Programming Button" until the LEDs alternate flashing amber, then release.
    • The LEDs will start alternating flashing green, and the radio will visibly restart.
12. Turn the vehicle off, close the doors, and let the vehicle sit for 5 minutes.

Setup and Configuration

1. Turn the ignition ON. LED 1 on the interface will turn ON, and the +12v remote output will turn ON.
2. Set the amp gain(s) to the desired level. It is recommended to use an oscilloscope and test tones for this process. Refer to the MECP Advanced study guide (p. 360) if unfamiliar.
3. Check volume, balance, fade, and EQ settings.
4. If you wish to adjust the chime volume or minimum volume, use one of the methods outlined below. If you are satisfied with the default levels, no adjustments are necessary.
   NOTE: The level control knob must be connected to the module for Minimum Volume or Chime adjustments.

Manually Setting the Chime Volume

You can manually set the factory chime level using either the programming button on the interface or the factory SWC. For AmpPRO PC app adjustment, proceed to that section.

Setting the chime volume using the programming button:

1. Start with the level control knob turned all the way down (counter-clockwise).
2. Press the programming button on the side of the interface.
3. LED 1 will turn green, and the chimes will begin continuously sounding.
4. Turn the level control knob clockwise until the desired chime level is reached.
5. You can now either press the programming button twice or wait ten seconds to exit the settings.

Setting the chime volume using the factory SWC:

1. Start with the level control knob turned all the way down.
2. Press and hold the track down button on the factory SWC (back left of steering wheel) for approximately ten seconds.
   NOTE: The radio will respond to SWC commands during this process; this is normal and has no effect on AP4 operation.
3. LED 1 will turn green, and the chimes will begin continuously sounding.
4. Turn the level control knob clockwise until the desired chime level is reached.
5. You can now either press the programming button twice or wait ten seconds to exit the settings.

Manually Setting the Minimum Volume

If the minimum volume of the radio (factory radio volume level 1) is too loud, you can manually set the minimum volume level using either the programming button or the factory SWC. For AmpPRO PC app adjustment, proceed to that section.

Setting the minimum volume using the programming button:

1. Start with the level control knob turned all the way down (counter-clockwise).
2. Set the amp gains to the desired level.
3. Set the volume on the factory radio to 1.
4. Press the programming button on the side of the interface twice.
5. LED 1 will turn amber, and the chimes will begin sounding every five seconds.
6. Turn the level control knob clockwise until the desired minimum volume level is reached.
7. You can now either press the programming button once or wait ten seconds to exit the settings.

Setting the minimum volume using the factory SWC:

1. Start with the level control knob turned all the way down (counter-clockwise).
2. Set the amp gains to the desired level.
3. Set the volume on the factory radio to 1.
4. Press and hold the track up button on the factory SWC (back left of steering wheel) for approximately ten seconds.
   NOTE: The radio will respond to SWC commands during this process; this is normal and has no effect on AP4 operation.
5. LED 1 will turn amber, and the chimes will begin sounding every five seconds.
6. Turn the level control knob clockwise until the desired minimum volume level is reached.
7. You can now either press the programming button once or wait ten seconds to exit the settings.

AmpPRO PC App

Use of the AmpPRO PC App allows you to:

• Configure User Interface Options such as:
  • Minimum Volume Level
  • Chime Volume Level
  • Enable / Disable AP4 Chimes
  • Enable / Disable factory EQ
  • Set Bass / Mid / Treble center frequencies and Q factor
• Update Product Firmware.
• Read Firmware / Hardware Versions.

You can download the AmpPRO app at: https://pac-audio.com/app-downloads/

NOTE: These settings can be adjusted with the module installed in the vehicle or on a bench. However, it is recommended to make adjustments with the module installed and the factory radio ON, so that the changes can be heard.

Setting Explanations:

• Minimum Volume Level: Allows you to set the minimum volume level of the factory radio (factory radio volume level 1).
• Chime Volume Level: Allows you to set the volume of the AP4 chimes (e.g., park sensors).
• Front / Rear Chimes Enabled: Allows you to enable / disable AP4 chimes (e.g., park sensors). This is used when mixing factory and aftermarket speakers.
• 3 Band EQ Enabled: Allows you to enable / disable the 3-band factory EQ.
• Bass / Mid / Treble Freq / Q Factor: Allows you to set the center frequency that will be adjusted when setting the 3-band factory EQ, as well as the Q Factor for each frequency. The Q Factor determines how many of the adjacent frequencies will be affected when adjusting the selected frequency. The lower the Q Factor, the more frequencies will be affected.

Available Frequencies and Q Factors

Firmware Updates

The AmpPRO app allows you to update the interface with new firmware as it becomes available. Please visit www.pac-audio.com or contact tech support to see if there is a firmware update for your interface.

Update Process:

1. Connect the interface to your PC and select "Firmware", then "Update Firmware".
2. Now select "Select File".
3. Finally, browse to the place where you saved the file and select it. This will begin the updating process.
4. Once finished, disconnect the interface from the PC and resume normal operation.

Radio Reset Procedure

The Radio Reset Procedure is used to speed up the installation process when re-configuring the radio for non-amplified vehicles or when OEM features are lost after installation. It is recommended to perform this procedure during the AmpPRO installation.

1. With the radio ON (LED 1 red), press and hold the programming button until the LEDs are alternating flashing amber.
2. Release the programming button (you have 5 seconds before it moves to the next function).
3. The LEDs will start alternating flashing green, and the radio will visibly restart.

Note: In vehicles that do not support this reset, the LEDs will not flash amber. You will instead need to complete the "Sleep Cycle Procedure" outlined below.

Sleep Cycle Procedure

The Sleep Cycle Procedure is used if the "Radio Reset Procedure" is unsuccessful in re-configuring a non-amplified system, restoring lost OEM radio features or graphics, or restoring the factory system after AmpPRO removal.

1. Turn the vehicle ignition OFF.
2. Exit the vehicle and close all doors, trunk, and/or tailgate.
3. Lock the vehicle with the keyfob and move the keyfob at least 25 feet away from the vehicle.
4. Let it sit for 10 minutes.
5. Unlock the doors, turn the ignition ON, and wait for the radio to boot up.
6. Repeat steps 1-5 for the second sleep cycle.

Restoring Factory Settings

Interface Reset

You can restore the interface to factory default settings by pressing and holding the programming button on the side of the module until the status LEDs start blinking red. Once the LEDs start blinking red, release the button.

This reset will restore the following settings to their factory defaults:

• Chime volume level
• Enable / Disable Factory Chimes
• Minimum volume level
• Enable / Disable factory EQ
• Factory EQ frequency
• Factory EQ Q factor

Restore Radio to Non-Amplified

If the AP4-CH42 was installed to a factory non-amplified vehicle, the radio was programmed to output a pre-amplified audio signal to the AP4. To restore the radio back to non-amplified programming, follow the steps below.

1. Remove the AP4-CH42 module and harness and re-connect the OEM radio connections back to factory.
2. Do 2 full sleep cycles (See page 5, "Sleep Cycle Procedure").
3. Test the radio to verify the vehicle was successfully restored:
   • Test that you have audio signals coming through both the front and rear channels.
   • Test that the audio is variable with the radio's volume knob.
   • If the audio is still only on the rear channels and does not change with the volume knob, repeat the sleep cycle process.

Troubleshooting

• Hiss at high amp gain: Set feature DIP switch 2 to the ON (down) position to lower the output voltage of the AP4 to 4v. If you still hear the hiss, lower your amp gains until the hiss is gone.
• Cannot hear uConnect or nav voice: Use the volume knob while either of these voice prompts are active to adjust voice volume.
• Cannot hear chimes: Set chime volume using the process outlined in Setup and Configuration, or using the AmpPRO app. If you still do not hear chimes, be sure that you are using the remote output from the AP4 to turn on your aftermarket amplifier.
• Low volume setting on radio is too loud: Set minimum volume using the process outlined in Setup and Configuration, or using the AmpPRO PC app.
• Module becomes unresponsive or will not power up: Turn the key to the ignition position, then press and hold the Volume Down button on the factory SWC for 12 seconds until a tone is heard.
• LED 1 is lit up red, but there is no audio: You have installed the AmpPRO into a non-amplified vehicle. You must have DIP switch 4 ON for this scenario.
• Audio is only playing out of the rear speakers and the volume knob does not work: You have re-configured the radio in a non-amplified vehicle and still have the cabin speakers connected to the factory radio. Aftermarket amplification on the cabin speakers must be used in this scenario.

LED Legend