jerlands

is there any relationship with the stereo amplifier and the power antenna?... at this point in time the stereo unit indicates it has power and is working however there is no sound output and the power antenna no longer operates.... i replace the stereo with a Kenwood KMM-BT728HD a while back and had heard what i though was ignition noise and went through shenanigans trying to eliminate it but was never successful... i've since read that if you don't bypass the stereo amplifier, you will burn it out but this info was for a 97' i believe... i'm not familiar with stereo components so much or how to balance them but the spec on the kenwood is Maximum Output Power 50 W × 4.
any insight will be appreciated...

LeX2K

There is no direct correlation the power antenna gets a signal from the stock head unit to power on. Are you using the factory amp now? Do you care about the power antenna? On my cars I disabled the signal wire the antenna since I never listen to terrestrial radio.

jerlands

to be frank... i'm confused about my installation... i'll have to go back and review... i picked up the unit from crutchfield using their instructions which included a wiring harness... the stereo itself has a 10a fuse but i'm not certain what would happen if it blew...

jerlands

the harness does show a power output to the amplifier so i am assuming it is in use... or... was... it may be possible the 10a fuse in the stereo prevents output to the amplifier?...

LeX2K

It's difficult for me to answer your questions without knowing exactly how the stereo is wired in but start with the basics check for any blown fuses. If I had to guess I'd say the remote wire from the head unit (which is designed to turn on an external amplifier) was used to operate the antenna as well as activate the Lexus amp. Maybe the power antenna failed and fried the remote output from your head unit.

jerlands

i've seen a post about how to bypass the amplifier but im confused by them... i think all it showed was a connector diagram...

LeX2K

Bypassing the Lexus amp simply means you connect the speakers directly to your Kenwood. But you'll lose the subwoofer and in general the sound will be bad.

jerlands

ok... i haven't yet looked around for a replacement amplifier yet but since you don't think the amp and the antenna are connected i'm going to look into that 10a fuse on the radio once i get around to it... or maybe try and find a schematic for the radio...

jerlands

i can't think of a good reason for the radio to have an internal fuse except to protect itself from the amplifier which it supplies power to... so i'm also gonna jump to conclusions and say the amp itself needs replacement and so i need recommendations for that... on the cheap.. which crutchfield is probably good for...

jerlands

i called kenwood tech support and they were unable to tell me what the fuse protected...

LeX2K

You need at minimum a test light to see if the head unit is outputting power to trigger the amp.

jerlands

it appears the power supply to the power antenna and also to the amplifier come from the same circuit off the radio...

jerlands

i'm gonna bet a nickel and say the fuse blew in the radio because of the amplifier... checking the fuse is easier than pulling the seat...

jerlands

i'm just going to assume i need a different amplifier because of what i'm reading around the board about this problem. i've briefly looked into this and see that it's a little confusing if you don't know what you're doing... to begin with... i don't know if i should be looking at a 4-channel or greater than?... https://www.clublexus.com/forums/lex...l#post10795426

BMeek

Yeah, that whole write-up I did was about the subsequent ES300 generation (3ES) amp bypass…

I gather that your new head unit sounded noisy while plugged into / “integrated with” the factory amp. No surprise. Now, your Kenwood lights up but you’re no longer getting sound from the speakers. Correct? If so, your assumption about a failed factory amp makes sense (although it’s possible you simply messed up the installation while trying to eliminate the noise :-).

As for the power antenna, the 3ES didn’t have such a thing, but if your 2ES was wired in a similar way, switched and constant 12v battery power go first into the amplifier and from there on to the head unit… it makes sense that the signal from the head unit to power on the amp also activates the antenna (also makes sense that a dead amp means no antenna action).

As I understand it, your ‘95 2ES has its factory amp located under the passenger seat. Since Metra specifies the same 70-8112 harness for your 2ES as is used in the 3ES to connect an aftermarket head unit, it’s likely that the same connectors are used on the amplifier end for the wire bundle from the head unit and then out to your factory speaker wiring (making this a logical place for you to locate an aftermarket amp).

It would probably make sense to collect/discuss more details, like some images of your factory amp’s location and (female) connectors and the (male) connectors going into it, in that other thread… I’m suspecting that the 2ES is similar connector-wise and the location of the factory amp & speaker wiring is the main difference, so I would be willing to entertain further questions about amp selection and subwoofer decisions there and ultimately annotate that OP with some “2ES notes” for the next person in your position (even though 2ES and 3ES units getting stereo upgrades these days are becoming pretty unusual :-).