996 Bose Subwoofer Retention for '01 - '02 Only
'01 - '02 996 vehicles that are bose equipped have a factory subwoofer that is powered by a secondary amplifier. This secondary amplifier is mounted to the primary amplifier in the trunk. When adding an aftermarket radio to these vehicles and keeping the factory speakers and amplifiers in place, the subwoofer volume can tend to be too high in relation to the other speakers in the car. There is an easy way to remedy this and gain full independent subwoofer level control through the controls on your new radio. There are two signal wires that run from the primary amplifier to the secondary subwoofer amplifier that can be intercepted and ran to the aftermarket radio.
The subwoofer signal wire colors are violet (signal +) and violet/brown (signal -). These two circuits simply jump from the larger primary amplifier to the smaller subwoofer amplifier that is piggybacked on the primary amplifier. Cut the two wires away from the primary amplifier and insulate the primary amplifier side. The two remaining wires attached to the subwoofer amplifier are your signal positive and negative inputs.
Amplifier SIgnal Input
Violet = Signal Positive
Violet/Brown = Signal Negative
The subwoofer retention harness has RCA connectors on one end and bare wire on the other. Connect the brown wire from the retention harness to the violet/brown signal input wire on the Bose subwoofer amplifier. Connect the red wire from the retention harness to the violet signal input wire on the Bose amplifier.
Connect the two RCAs to the subwoofer output at the radio.
Running the RCAs
Unbolt the 13 mm battery hold down on the passenger's side of the battery. Unbolt the negative battery ground point from the body of the car in the battery compartment. The battery can now be slid over to the passenger's side of the battery tray. This will give you easy access to the large rubber grommet located behind the battery on the driver's side of the firewall. this grommet is generally unpopulated and can be pushed back into the passenger compartment. There will be fuzzy sound deadener on the passenger compartment side of the grommet. The sound deadener has been perforated at the factory and will easily tear out. The grommet is located directly above the gas pedal inside the car. retrieve the grommet and pierce a hole in it large enough to push the RCAs through but small enough to keep a decent seal. The grommet can now be reinserted from the battery compartment side of the firewall.
Once inside the passenger compartment, run the RCAs to the radio location. Be sure to avoid the large black battery cable that runs along the heater duct on the left hand side of the radio. Cross the battery cable at a 90 degree angle and do not run parallel to it. This battery cable can cause electrical noise problems in the audio system if the RCA cable is in too close proximity.
Secure all cabling with zip ties so that they can not interfere with operation of the clutch, brake, or gas pedals.
Slide the battery back into place and re-secure with the hold down bolt. Reconnect the battery negative ground point.
From the radio make sure that the subwoofer output feature is turned on. Adjust the subwoofer level to your desire.