Factory Amplifier Bypass
A number of owners have been dissatisfied with the sound quality of the factory radio system installed in the Impala. A proposed solution was to bypass the amplifier installed in the trunk and drive the rear speakers with the head unit alone. I am pretty happy with the sound in my car so I have never attempted a bypass. Truth be told, if I wanted to do an upgrade, I would replace the amp with an aftermarket one and upgrade the speakers. One person has done this and you can see the whole operation on his web site My Loud Car. See the links page.
You can find all this info by reading the Impala Radio forum on Edmund's Town Hall. I am posting it here because it is difficult to find anything since they changed the software.
1) I did not come up with any of this. Credit should be given to the members from Edmund's Impala Radio Town Hall. Duraflex, who's post I have included below. Smithy101, who posted a photo of the bypass. Jreimann, who posted a copy of the plug outputs. Humahuma, for finding the amp plug diagram. If I forgot anyone, please let me know.
2) I have not done this bypass so I can't say how well it works or how it will affect your radio. You CAN burn out the internal amplifier circuit in the head unit if you attempt to push it too hard. I have done this on a few other radios. =P
The following is a quoatation from the Impala Radio forum on the Edmunds Town Hall.
#201 of 353 TO bypassers-to-be PLEASE READ THIS by duraflex Jun 16, 2000 (01:06 pm)
Duraflex here. (Turned out long, but here goes)
The poster above was trying to be helpful but did NOT quote my post #180 in its entirety.
Aside from omitting important details, he also left out this caveat:
If you do the trunk amp bypass, IT IS COMPLETELY AT YOUR OWN RISK.
This is merely a makeshift "fix" for something GM/Chevrolet should have gotten right in the first place. Although it sounds much better, especially at low to moderate listening levels, I still have reservations about it. I still think GM should do a recall and fix it properly and assure us of its safety.
I did not arrive at this "solution" alone - although I may have helped push the issue and lead the way.
Jmahler - a guy who's been reading prints for 40 years - came up with the wiring combo.
Humahuma first planted the notion that a trunk amp bypass was possible.
Smithy101 - another neat guy over here who participates in car audio competitions posted my composite picture of just how simple it is.
To see it, click on this link: http://www.myloudcar.com/2000impala/bypass/Bypass1d.jpg
(Look at what he's doing while you're at it!)
Also, bypassers-to-be should at least read all the subsequent posts (after 180) to get a full picture of what this is all about BEFORE deciding to do it.
Finally let me add this:
This bypass will give you a LOT MORE BASS - potentially TOO MUCH BASS if you're not careful - you COULD literally blow the speakers!!!
SOOOOOOOOOO When you're finally ready to try this and are just about to do it, Re-read this:
(Please, PRINT THIS or WRITE IT DOWN.)
The radio is a push-on/push-off design, so some precautions are required to avoid post bypass overload!
Turn the radio on.
Turn the VOLUME DOWN VERY LOW.
Put the tone on MANUAL.
Turn the BASS DOWN - at least two notches left of center.
Next, push off the radio power.
Take the key out.
Refer to POST#180.
You're likely to love the new sound.
When it's all said and done, DO NOT play it TOO loud or with too much BASS. I repeat - IF you do, YOU can and YOU will blow your speakers!!!
And for safety's sake, please remember you're still DRIVING a car!
Be careful and Good Luck. "Duraflex"
I don't know what post #180 is. Unfortunately, it looks like Edmunds renumbered the posts or something because post #180 does not really add to Duraflex's post. However, this is what I found:
#162 of 353 Ref; Post 167 BY_PASSING AMP-duraflexuraflex by mahler1 Jun 09, 2000 (07:09 pm)
I have a copy of the Amp. Plug wiring diagram and suggest you use these strappins for an 8-speaker system with amp.
Left spkr Right spkr
B1-to-B9 (LF-) A1-to-A9 (RF-)
B2 to B10 (LF+) A2 to A10 (RF-+)
B3 to B11 (LR-) A3 to A11 (RR-)
B4 to B12 (LR+) A4 to A12 (RR+)
My recommendation is to read the whole message board before you attempt anything. You can go there by clicking on THIS LINK.