There are a few models that develop this problem but two have a 100 percent failure rate. One is the cd / radio and one is the cassette / radio. What fails is the microprocessor IC that was made by North American Philips, (NAP), the same people who make the really crappy Sylvania / Magnavox / Philips tvs. I have the equipment to replace them but then the software has to be "burned in". They will never sell me the equipment to do that!
This pertains to the round-face radios with three lighted tone controls. They are built by Chrysler and have "supplier code 7910" on the model number sticker. There are nearly identical models built by Mitsubishi that look the same, mount the same, and run the same remote cd changers if you have one. I sell a lot of these for replacements. Used car dealers all over the nation hunt for them too for their used cars.
A lot of mechanics unfairly get the blame for damaging these radios because the problem usually shows up right after they worked on the car. What happens is the "reset" circuit fails but you will never know it until the battery is disconnected. When power is reapplied to the memory wire, that circuit "resets" all of the millions of transistors in the microprocessor to their starting point. That circuit functions only one time for a fraction of a second each time power is reapplied to the memory circuit, not through the ignition switch, so it could potentially operate only a dozen times in the life of the vehicle. Every microprocessor has that circuit. As long as power remains applied, meaning the battery is not disconnected and no fuses are blown or removed, the microprocessor will continue to work. It's when the battery is disconnected, as specified in the service manual for many other repairs, that the problem shows up.
This problem is similar to a failed starter motor. You will never know it failed until you stop the engine and try to restart it. Until then, the engine will continue to run just fine.
Tuesday, January 18th, 2011 AT 3:16 PM