The term "power antenna" can be misleading so many manufacturers call it "remote" now to avoid confusion. It gets 12 volts switched onto it when the ignition switch and radio are turned on. That will trigger a power antenna to go up and it will turn on a remote amplifier which a lot of cars have.
The fact that there was sound at first suggests there is no remote amp in your car or the "remote" wire was connected correctly. I'd start by testing for voltage at the new radio's connector. One wire must have 12 volts all the time for the memory circuit, and a different wire must have 12 volts only when the ignition switch is turned on. Also be sure there is a good ground wire either in the harness or from the body of the radio to the body of the car. If there's no ground wire, the radio will get grounded through the outer shield of the antenna cable but that is a very poor power ground. Enough current might get through to run the display but not enough to run the audio output circuit. You can often get a clue to a bad ground by observing the display dimming or flickering when you try to play a cd.
Ground your voltmeter to the car body, then measure for voltage on the metal case of the radio. If you find anything more than 0.0 volts, run an extra ground wire from the radio to the car body.
Some people also get confused when looking for a ground wire in the car's harness. There will be a wire coming from the tail light circuit to tell the original radio's display to dim when the head lights are turned on. Another wire comes from the dash lights to tell the display how much to dim. Both of those wires will read very low resistance to ground because you're reading through all the light bulbs on those circuits. If you used the dash light wire for the radio's ground, the radio might play at times depending on where the dash light rheostat is set. With the lights turned on, voltage will be on that circuit causing the radio to turn off, but it usually causes the dash light fuse to blow also. This will show up, again, by measuring and finding voltage on the case of the radio.
All radio models have their own characteristic when the 12 volt memory circuit is dead. Some don't even turn on. Some turn on and make light static in the speakers but there's no display. Some appear to work but there's no sound. Some work fine but they don't maintain your station presets, and the clock goes back to 12:00 or 10:00 each time you turn it on. Even those clues can be misleading on some models because they can use a memory capacitor, which is like a very tiny battery, to maintain the memory for short periods of time. While that holds the station presets and clock giving the impression the memory circuit is working, in fact that memory wire could still be dead. Typically a blown fuse causes the dead memory circuit but it's often labeled something else. The memory circuit is tied in with something else that is always hot such as interior lights, cigarette lighter, or horn.
Some radios have a muting circuit to kill the sound such as when you have a hands-free cell phone or talking dash board. That is different than the internal muting circuit that kills the static when you don't have a strong radio station tuned in. (That circuit wouldn't affect the sound from the cd player). If there's a wire in the harness for "mute", the installation manual should specify if that wire has to be grounded or be connected to 12 volts. If it's not connected, the voltage on it can "float" to some unknown value from other circuitry in the radio and may hit the point of triggering to turn the sound off. That circuit WILL affect the radio and the cd player.
Just about every radio out there today uses two wires for each speaker, and none of them can be grounded. They will all have close to 6.0 volts on them. Some radios detect a grounded wire and turn off the audio output circuit to protect it. Some models turn off only the affected channel, and some turn off all of them. For example, Chrysler had some low-end radios in the '90s that would turn off all the sound when a speaker wire was grounded but that short would bypass part of the protection circuitry so only the speaker with the short would play at very low volume. Made it easy to identify the problem channel. What you might have to do is measure the voltage on all 8 speaker wires with the radio turned on. Don't use anything but a digital voltmeter. A test light can load the circuit with too little resistance to ground and burn out an output I.C. Most of these detection circuits do their thing when you first turn the radio on. If there's no shorted speaker wire, they turn on the output stages, but if a speaker wire becomes grounded after that, an output I.C. May be damaged. On some models, the protection circuit will kick in after the radio is playing if that's when a short occurs.
The place to start looking is with your connections to the car's radio harness. If you twisted wires together and taped them, start over by soldering all connections, flattening any sharp points that are sticking up, then slide a piece of heat-shrink tubing over the connection to seal it. Electrical tape will unravel into a gooey mess on a hot summer day leading to all kinds of problems.
If you used an adapter harness, look at all of the terminals on both ends to see if any of them are pushed out. They were hand-assembled and sometimes a terminal doesn't get pushed in far enough to catch on the locking finger. It's not unheard of for a wire to be installed in the wrong location either although that's not real common.
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Tuesday, April 17th, 2012 AT 8:52 PM
