AUX in Jack for my Car

I have a cool little CD player that I picked up at Goodwill for $3.00. I’ve been using it with a small FM transmitter, to listen to CDs in my car. There was always a bit of static, the CDs sounded flat and recently, a station in my area began transmitting on multiple frequencies, making the FM transmitter almost unusable.

I wanted to be able to plug my CD player directly into my car radio so I stopped into RadioShack and picked up a 1/8inch stereo plug to 1/8inch stereo plug patch cable and a 1/8 inch stereo jack.


I thought the hard part was going to be getting the radio out. Once I popped the trim off there were three screws to remove and the radio slid right out. I had to work the radio around the trim, but was able to get it out enough to remove the top and bottom covers.


Next, I had to find the signal from the radio frequency module to the amplifier portion (I actually did this step in he car and later took this photo on the work bench).

I plugged the cable that I purchased into the headphone jack of the CD player, connected a ground wire from the plug on the cable to the ground of the car and began trying the tip on various connections in the radio. I eventually found the left and right signals. I used my Black & Decker “Wizard” (like a Dremel) to cut the traces.


Next, I cut the circuit board on the face plate of the radio and drilled a hole for the jack. The jack was small enough to fit under the circuit board, but there weren’t any traces on the circuit board where the jack was going so I just got it out of the way.


I soldered wires so that when the patch cable was removed from the jack, the traces were reconnected. When the plug was inserted, the signal from the CD player was connected to the amp side.

When I put it back together and tested it, it didn’t work. The radio played when the patch cord was removed, but the CD wouldn’t play. After some trial and error I found out that radio cut out when the traces were cut. I had to short them together.

When the CD plays, it cuts out the radio, when it’s off, the radio plays and it sounds great. I almost can’t wait to go to work tomorrow, so I can listen to CDs on the way in.

This project was on a 99 Alero with the stock Delco radio.

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