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AHB-T Harley Radio Interface Harness For Amplifiers


  1. Optional Accessory Input. This optional plug should be left disconnected if you are using a DSR1. This plug connects to the bikes accessory circuit located behind the voltage gauge. This circuit gets 12 volts only when the bike is in accessory or ignition mode. When connected 12 volts is sent through the harness to the accessory output on section #1 of the harness. (See pic 1 above). DSR1 sound processors should not be connected to the bikes accessory. The DSR1 has a feature built into it called DC Detect. If the bike's accessory is connected to the DSR1 the DC Detect feature will be overridden and a nasty turn on pop will occur. This wire is Blue or Red depending on the production date.

  2. Disconnect the main harness from radio and connect this section to that radio harness. 

  3. Connect to factory radio.

  4. Speaker level RCA outputs. Connect to aftermarket DSP or amplifier inputs. If the RCA outputs are not labeled, refer to the speaker wire color codes below to identify channels (i.e. left/front, right/front, left/rear, right/rear).

  5. Power, ground, & accessory output for optional DSP. This is for low current devices (less than 2 amperes of current) only! Not intended to power amplifiers. If not using these connections, disconnect the four pin plug and do not use the male end of this harness in your installation. Note: DO NOT CONNECT FOUR PIN FEMALE PLUG TO ANY PART OF FACTORY HARLEY HARNESS!

  6. Speaker outputs. Connect to aftermarket amplifier outputs for factory speaker locations. 


Some newer versions of this wire harness will have color coded speaker wires for the factory speaker lines. 

White = Left Front +

White/Black = Left Front -

Grey = Right Front +

Grey/Black = Right Front -

Green = Left Rear +

Green/Black = Left Rear -

Violet = Right Rear +

Violet/Black = Right Rear -

This harness is designed to intercept audio signal exiting the factory radio before it is sent to the factory speaker locations or to factory amplifiers. By intercepting the signal before any optional factory amplifiers both audio signal and speaker connections become universal for all trim levels of Harley touring bikes. This includes all non amplified and amplified variations including CVO and Ultra models. 


This harness has a built in resistor network that dramatically reduces distortion from the factory radio. Audio signal at the RCAs of this harness is full voltage speaker level. There is no reduction in signal. This is not a high to low level converter and care must be taken not to short any part of the RCA to chassis ground or to each other. Doing so can cause damage to the radio. Though the load resistor network eliminates distortion, your bike will still need to be either flashed or you will need to use a DSP like a DSR1 in order to compensate for the wild and unfriendly frequency response of your factory radio. Or even better, do both. You can find both options here. 


Speaker Level at RCAs

Not compatible with amplifiers or DSP modules that have common grounded RCA shields. Be sure to verify that the device you plug the RCAs into has the ability to accept full speaker level signal on an RCA type connection. 

Four Pin Female Plug

The four pin female plug (number 5 in the pic above) is power output for an optional DSP. It should never be plugged into the rear speaker output plug of the factory radio. Doing so will damage the radio.

Factory Amplifiers

Bikes with factory amplifiers will also require additional amplifier bypass plugs in order to loop the audio input signal for factory amplifiers out to the factory speaker outputs of the factory amplifier wire harness. You can find amplifier bypass plugs here.


Uninsulated butt connectors are used on this harness. You can use these connectors in conjunction with heat shrink or tape and crimp directly to bare wire connections such as those found on Diamond and Rockford Fosgate mini amplifiers or you can use them as wire ferrules and insert them directly into the connectors on amplifiers with Allen terminals like the ones you find on Diamond Audio HXM series amplifiers. 

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AHB-T Harley Radio Interface Harness for Amplifiers

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