A CD changer can be great for a long road trip because you can put as many as six CDs in the player. However, the changer has many working parts that wear out in time or get out of whack. Here's an overview on how to fix the problems.
Check the fuse box to see that fuses are good if the CD player is dead. The owner's manual will have the fuse chart. Then check the wires for proper connection.
First unhook one of the car battery terminals for a few minutes. If the CD player turns on but the CD doesn't eject or will not play or accept CDs, this will reset the changer and may make the changer work again.
Determine the location of the CD changer. The changer will be mounted in the dashboard with your radio, in the glovebox or in the boot.
Try running a CD lens cleaner through the changer. Often, error messages or CD rejection occurs because the lens isn't clean. Running a lens cleaner through the player will help this.
Confirm that gears connecting the motor to the piece that grabs the CD are actually connected. To do this, open the unit (steps vary with the device). If not, adjust with appropriate tools. Once this is done, close the unit and reinstall into the car.
Unhook the changer from the mounting brackets. Mark the wires so you'll know where to plug them correctly into the new changer, then unplug from the old changer.
Plug the wires into the new changer. Remount the unit to the mounting brackets. Test the unit to make sure it works. If your unit is dash-mounted, test the unit to make sure it works before putting the dash back in.
Use a container to keep track of any bolts or nuts unhooked so you can reuse them.
Disconnect the battery cable before any disassembly to avoid risk of shock. Take note of the wiring's polarity, because you can mess up the electronics if the polarity is reversed