Thread: Plans to upgrade 2001 GT with Bose, but keep stock head unit.

While refurbishing the door trim panels on my new/old 2001 Grand Prix GT (see new/old post in Intro/Noob forum), I decided to replace the Bose door speakers with some Infinity speakers, and a pair of component Boston Acoustics tweeters leftover from the custom system in my old (now gone/totaled) Bonneville.

Like many who have gone before me and replaced the Bose stock speakers but retained the stock head unit and amplifier, I found the results to be predictably underwhelming. Despite being pretty low impedance, the volume level from the aftermarket speakers is considerably lower than the stock Bose speakers. That being said, it's also blaringly obvious that the aftermarket speakers are of considerably higher quality than the cheap paper Bose/stock speakers, and I believe I've got a solid plan for improving the audio experience.

Through lots of web research, I believe the quality and signal output level of the stock `01 head unit is actually quite good. So my plan is to route the front audio to an aftermarket amplifier. I have lots of leftover audio gear from my old Bonneville, including some excellent Alpine amplifiers.

Based on the wiring diagram for the stereo: https://dl.dropboxusercontent.com/u/...1/WIRING53.pdf
This is my plan:

In the trunk, where the wiring harness connects to the amp under the rear shelf panel, I plan to cut the following wires and put male/female spade terminals on the cut wires, so they can be reconnected or rerouted to the aftermarket amplifier:
Tan #511 LF+ at terminal B10
Dk Grn #1947 LF- at terminal B9
Lt Grn #512 RF+ at terminal B8
Lt Grn/Wht #1948 at terminal B7

I'll use those for the signal inputs to the aftermarket amp to drive the front speakers.

Tap pink wire #314 Radio On, and use for aftermarket amp turn-on.
I'll run separate battery power and ground wires to the amplier.

Then cut the following wires and put male/female spade terminals on the cut wires, so they can be reconnected or rerouted to the aftermarket amplifier:
Tan #201 to LF+ speaker at terminal A11
Gry #118 to LF- speaker at terminal A12
Lt Grn #200 RF+ speaker at terminal A9
Dk Grn #117 RF- speaker at terminal A10

I'll connect the aftermarket amplifier's speaker outputs to those wires going back out through the harness to the front door speakers.

At least for now, this will leave the rear speakers being driven by the stock amp under the rear shelf panel.

That's my plan. It cleverly re-uses the existing wiring harness to get the line-level signals from the head unit to the trunk, where the aftermarket amplifier will be mounted, and re-uses the existing wiring harness to get the speaker-level signals from the amplifier back to the door speakers.

There is an aftermarket device, the PAC AOEM-GM24 http://a.co/3civiab that appears to tap the line-level outputs, but I can't tell if it mates with the wiring harness connector at the under-rear-shelf amplifier, or if it mates with the wiring harness that plugs into the head unit in the dash, and it doesn't offer a tap into the wires that go to the speakers, as that device retains the existing connections between the rear-shelf stock amplifier and the speakers.

For what I'm planning, I think my plan to cut those select wires at the harness in the trunk is better, and my plan to put male/female spade terminals on the cut wires will be useful if I ever want to remove my aftermarket amplifier and re-connect the OEM amplifier.

Any opinions on this? Am I risking noises? I've gone over this pretty thoroughly, and if time and weather permits, may get started this weekend.

If the bose system amp output uses the same as every other gm ever then its

LF Speaker +/- tan - gray
RF Speaker +/- lt. green - dk. green
LR Speaker +/- brown - yellow
RR Speaker +/- dk. blue - lt. blue

You can test them with a AA battery, just run that 1.5 volts into the wires. The speakers you hit with it will make a small pop. and 1.5v wont hurt anything.

Originally Posted by 01Blackgtp

If the bose system amp output uses the same as every other gm ever then its

LF Speaker +/- tan - gray
RF Speaker +/- lt. green - dk. green
LR Speaker +/- brown - yellow
RR Speaker +/- dk. blue - lt. blue

I'm after the line signal wires from the head unit to the Bose amplifier and the amp turn-on wire as well, at the wiring harness connectors that go to the Bose amp.

So the PAC AOEM-GM24 is an interesting device, but it isn't wired properly for the 2000-2001 Grand Prix Bose amp harness.
Ordinarily, it just plugs in between the car harness and the Bose amp. All 24 wires are connected straight-through, and 8 wires are tapped off that go to a connector to the AOEM adapter. Inside that adapter there are 4 resistors, 4 isolation transformers, 4 attenuator pots, and 4 RCA female output cables for line outputs.


Unfortunately, it taps the wrong wires at the 2000-2001 Grand Prix Bose harness, so the best use for this is to use only the short wiring harness to cut any wires you need to tap, and avoid cutting into your car's harness. I've confirmed that the Bose amplifier provides amplification for all eight speakers in the car. (For some time I had suspected that the front speakers were actually amplified by the head unit and that the Bose amp merely passed-through those signals. But it doesn't do that. The Bose amplifier provides amplification for all four corners.)

To bypass the Bose amp for only the front speakers, you can do it with just the short harness from the AOEM-GM24. However, the speaker wire lines going out to the rear "sub" 6x9 speakers and the speaker wire lines going out to the *left* side trunk round speaker are located on the other 8-pin connector, which also carries +Battery power and -Ground to power the Bose amp. If you're also going to bypass the Bose amp for the rear speakers (to drive aftermarket speakers, for example), you can just run separate wires from your amp to all of the trunk speakers, since everything is in the trunk. If you really wanted to connect to the 8-pin connector, you can get that with the Metra 70-2054 harness.


That harness contains both the 24-pin and the 8-pin connectors, but it appears to be missing a number of wires and looks only good for connecting up the wires going out to the speakers. The 8-pin harness in the Metra 70-2054 is the same way, having only the connectors going out to the speakers and lacking the +Battery and -Ground connections. Even so, the Battery and ground wires in the stock harness appear to be around 12 gauge, and you really ought to run something bigger if you're going to run an aftermarket amplifier. The Metra harness also costs more than the AOEM-GM24 device, so the short bypass harness in the PAC AOEM-GM24 really appears to be the best choice for running aftermarket speakers and amplifier without running new speaker wires and without cutting into the factory harness.