Have a 1979 Corvette with NO external amp. Bought the car about 3 months ago; had a Pioneer AM/FM/CD unit in it and worked well. Drove it one Saturday about 3 weeks ago, pulled it into the garage, shut off the radio, turned off the car. All was well. Went out the following weekend to drive it - started the car and turned on the radio but no audio. Unit / head powered on - showed it was working but no sound through any of the speakers for the radio or CD. Pulled the unit and since it was 16 years old I assumed just an internal failure so I bought a new Kenwood unit. Hooked this unit up in car, head comes all but still no audio through speakers. I have power to unit and it scrolls all through the menu and it DOES bench test out of the car just fine. I have directly rewired all speakers to the new Kenwood provided harness to eliminate the possibility of an external amp that I can't find or am unaware of. Any thoughts on what it could be? Old Pioneer unit that was in it worked fine but audio also stopped with it - that's why I replaced with the new Kenwood. Rewiring the speakers all directly should have eliminated any external amp if there was one but there is not. Any help would be appreciated. Again, I pull the unit and speakers out of the car, hook it to a battery and they work fine - the thing sounds great out of the car! Put it back in, everything powers up but no audio. What am I missing - what could have happened? THANKS in advance!

 

It seems like you have covered all the bases on this issue. One thing you might want to try is to connect the radio power and standby wires (usually the red and yellow) directly to the battery + with the rest of the system still in the car. Also look for any other connections other than the four speaker wires, two power wires and the ground that might be present in the car wiring and if so see what they are. My Kenwood has other connections like a mute control wire and a power control wire to turn off the Kenwood power output under certain conditions.

Redvette2

 

Thanks. I'll try "bench testing" in the car by hooking up the red / yellow and negative directly to the battery. Wired it directly into the car harness like the Pioneer was. I don't see any other wires in the car harness that I could be missing but then again... This one also has the mute, etc. however per the install manual I've not hooked them up to anything since they are NOT in use. Should be a simple swap = yellow to battery, red to the accessory lead, black to ground, then the 4 speakers. A no brainer, huh? Don't understand what has happened.

Thanks again and I'll let you know in a day or so.

 

Lets check the speakers first-

Disconnect the wires at the back of the radio-

Get a double A battery to use as a test-

For each speaker-just touch (briefly) the wires to the battery (polarity doesn't matter) and you should hear a pop. No pops at all? Then you might have a hidden amp somewhere?

If all of the(or most of them) speakers pop- then turn on the radio and try connecting one speaker at a time- a speaker that has a rubbing voice coil and grounded to the car will cause the radio to protect it self and go into a protection mode.

Let us know what you find.

 

Thanks for the info. The speakers are fine. I've tested each one outside the vehicle when doing the "bench test". As mentioned I have pulled new wire to each speaker so I would think if there was a hidden amp somewhere when I straight wired each speaker that would have taken any external amp out of the equation. Each speaker does pop / static when the radio is powered on and in the car. I have tried them collectively and individually with the same result in the car - they pop / static but no audio. Take them out of the car and connect to the head and they work fine - again both individually and collectively.

Tried your test - thanks for the suggestion, I've not heard of that one before so thanks again!!!, and each popped in the car. I'm at a loss. Seems like the thing is possessed or something! LOL!

Thanks again.

 

crahschu, you should pay particular attention to this statement by Richard454. Given the tests you've done, if the speakers are working fine out of the car, but not in the car, indicates a bad installation could be grounding out one or more of the speakers.

DC

 

Where would the ground be? I've checked with Kenwood Tech Support and they said no, if there was a ground issue the unit would not power on. That, plus the fact that I have removed and reinstalled all 4 speakers plus ran new wire to them seems to me that it would eliminate the ground potential. Thoughts on where I should look?

Thanks!

 

There are two ground so to speak. The radio has to see a DC (12V) power and ground to work... The speakers albeit AC voltage have to see power and ground too- AKA positive and negative. However if the AC (speaker output) is somehow grounded to the car -DC ground-- that's a problem.

Odd that not one speaker would play- try taking a speaker and just connecting it to the back of the radio while in the car.

let me know what happens.

OK- just another thought- at the back of the radio- using one speaker's leads- take one side of the battery and ground it to the car then touch the other side of the battery to one of the speaker leads and then the other lead. IF you hear a pop- the speaker might have a ground on the basket.

Richard

 

May have found it but I stress MAY... Might have been just a bad ground in the car harness itself if that makes sense. Took the advice of RedVette2 and connected the control head directly to the battery in the car with one speaker and it worked. Then wired the head into the power lines of the harness but left the ground wire attached to the negative battery post and the one speaker worked. Getting late and lots of other stuff to do so I'll check it out more in the next few days.

Really want to thank all that replied and offered suggestions and help. It is greatly appreciated! I normally don't listen to the radio while driving anymore but there is just something about a sunny day, tops off, and the iPod blaring that makes it special!

As far as Kenwood Tech Support, I e-mailed them and called them twice. They didn't even offer help - just that I should go to a professional installer.

Thanks again!

 

HA- one of my first real jobs was with Kenwood doing technical support...1986

 

Yahoo...progress! If the radio lights up it seems like the ground is there. Almost feels like the + power inputs are not right. Check the Red (ignition wire/switched), Yellow (direct battery wire), and the Black (ground wire) connections are acting correctly. Make sure when you turn on the car that the correct wire functions are still there and do not go away.

Redvette2

 

Thought about that too - I might have the positives switched but definitely not. Yellow is to the battery / hot and red is switched to the accessory. It's weird.

 

If you are not losing the yellow main power connection perhaps the ground wire connection is going away somehow? Try rewiring the stereo ground connection directly to the chassis. My PO(s) did so many strange things to my car that I ended up taking out about 10 ft of extra wires that went all over the car.

Redvette2

 

Most modern radio heads have a power feed to the control head AND a main power feed to the amplifier section. Sounds like the main power line is 'dead'. Check out the schematic for the radio connections and make sure that ALL 12vdc power lines going INTO the radio are actually 'live'. Problem could be as simple as a blown fuse or circuit breaker, or possibly a fried fusible link in the car's wiring (in the circuit feeding the radio's amp section).

 

Nope- not since the early 90's...and I worked for Kenwood.at the time...

The design was to have ONE power source- the yellow wire- constant battery wire. The red wire JUST triggers the radio on- and that's it. No power from either source- the radio will not light up...AND the radio has ONE fuse on the back...

The reason was to help eliminate the possibility of noise and installation issues when the radio was hooked up incorrectly (loosing memory mainly due to hooking the constant source to a switched ignition source and pulling too much power off the OEM radio wire was causing problems with the factory/OEM computers)

Using TWO different power sources - you had a greater chance to have engine noise enter the radio as often the switched ignition wire was a "dirty" source.. Also it was cheaper- as the trigger "ignition" wire no longer need to have a LC filter (noise filter using an inductor and a cap) on it...and as mentioned only one fuse instead of two

Richard

 

What if one of the power connections was low instead of missing? Some stereos spec sheets say they will stop working if the voltage goes below about 9-10V.

Redvette2

Edit Update: From the radios perspective, a poor ground connection might also make the operating voltage presented look too low. Maybe the ignition will light up the radio but not allow the power circuit to come on due to what it sees as a low voltage battery connection.

 

That's a possibly-but the antenna shield would also act as a ground as well- you could unplug the antenna and see what happens- or put a voltmeter at the radio's power wires- or best hit the power/ignition wires (yellow/red) and ground directly to the battery as you stated first.-

Try a speaker connected at the back of the radio and then try the speakers(one at a time) through the wire run in the car. Randomly trying stuff leads to a lot of wasted time. Basics first- then add on till it stops working.

Richard

 

IF the radio powers on and functions like normal just no sound, you may have had a speaker wire get chewed by a mouse or get pinched and contact a ground this will blow the internal amp in the radio. I have had this happen.

 

Yes this works great...have used it on my home and car stereos. Also you can use this technique to check the proper phasing of the speakers. If you carefully watch the speaker cone when first applying the battery it will move in one direction due to the DC current from the battery...either in or out. Both left and right speakers should match directions if you keep the battery connections the same at the amplifier (battery plus to speaker wire plus, etc.).

Redvette2

 

Another way to quickly check phasing-

Put the loudness button on (if so equipped)\and turn the bass up all the way. Turn the fader to the front - with low volume- go left to right with the balance- IF you have less bass in the center- speakers out of phase- then do the same for the rear.

Richard