You should bench-test a car stereo before it is installed, especially if it is a used unit. This will save you from trying to troubleshoot it after it is installed in the cramped quarter of the vehicle’s dash. Bench-testing a car stereo is a straightforward process as speaker wiring is paired into colors that are standard across the industry. You can quickly bench-test a car stereo with a few test leads, a spare speaker and a power source. Tips Warnings
