There is probably a wiring problem.
Turn up the volume.
Doyou mean LS400 lexus? The amplifier is integrated with the radio that power the speakers. Be aware that removing the radio on a LEXUS it may not work afterward because of a memory code installed into the radio to make inpossible to steal it.
lincoln has a standard radio which has a booster amplifier mounted in truck behind carpet of rear seat. there are no power amps like bose in each speaker it just boosts stock radio output from amp to speakers
yes
According to http://www.installdr.com/Harnesses/GM-Wiring.pdf the connector for the rear speakers is separate from the front speakers. If the connector for the rear speakers is loose or disconnected, the rear speakers would not work while the front ones will. The amp in the head unit (dashboard radio) powers the front door speakers. The rear door speakers and roof (pillar) speakers in the rear are powered by a second amp under the drivers seat. Either this amp is bad or is not hooked up.
some do have rear speakers but you will have to check it
The back seat has to come out and the seat back and the package tray has to also come out and then you can get to the bolts that hold the speakers in at the back, as far as the door speakers you have to take the inside door panels off and then you can get to the bolts to the door speakers.
buy and install an FM modulator. it works off of the FM radio.
You can get aftermarket car seat heaters installed at most local mechanics. You can also install your own car seat heaters if you follow instructions provided by websites such as heat Your Seat and Heated Seat Kits.
Remove the stereo and check that all the circuitry is fine in the disfunctioning radio. You should also check the fuses located under the hood/dash/near drivers seat in panel. Test fuses using a jumper wire, test light or ohmmeter. If you have a faulty fuse, replace it with the correct value. It sounds like the premuim sound system is installed. If this is the case, look under the dash and/or the driver's seat. There will be a small silver colored aluminum box. This is the power amp for the middle speakers (at the passenger doors). The pink wire is the activation wire. Once activated, all your speakers should work.
A rear seat could be installed in a cargo van with the right hardware. Seatbelts will also need to be installed to make this type of seat legal when passengers are present.
When transporting a baby in a car one must always have a current model car seat. It is recommended that your car seat be installed by professionals at your local dealership. A child seat must never be installed in the front seat. If your car has rear airbags the seat should be installed in the middle of the vehicle seat to avoid injury in case of an accident.