Car Stereos: 1999 lexus gs300, car stereo wiring, lexus gs300

Question
Hi Scott,
On my gs300 I have replaced an after market head unit to listen to mp3 files. I had it done professionally and the guy by-passed the factory amplifier. But the factory sub stops working...it sounds terrible without bass...and my question is: Is it possible to hook up the aftermarket head unit and still be able to use the the factory amplifier and sub?? and If so, which wire directly behind the factory head unit is the AMP-TURN on wire?....thank you so much Scott!!

Answer
Jane,

That is terrible.  Talk about a step backwards.  Usually, they make wiring adapters that help in the installation process, but some vehicles have very technical wiring.  Yours is one of these cases.  Unfortunately, I do not know the exact wiring for your car.  I hate to tell you to take it to a professional, because yours did not know what he was doing.  If the system amp has been bypassed via a jumper adapter, then there are two possible fixes.  First, unbypass the amp, and custom connect the wires how they are supposed to be connected.  Second, leave the bypass, but add a sub amp and wire to subwoofer.  Either way, the installation will require some specific model knowledge, and some custom wiring knowledge.  Most installers will not let a such a mistake pass.  I would find another installer and ask them if they can make it right.  They will either suggest custom wiring (my pick) or adding a sub amp.  If not, then ask them exactly what the plan is, and make sure they are understanding the problem correctly.  I am sorry I could not be more specific for you, but even so, it would require some pretty technical knowledge of car stereo wiring.  Let me know if noone can help you.  Hope this helps, Scott