Why does my radio cut in and out while the car is running?

• Voltage to the radio in not consistent. Using a multi meter be sure both red and yellow wires show at least 12 volts while the car is running and never goes higher than 14.9 volts. Also, be sure the ground (black wire) is connected to a clean metal point not sharing other electronic such as tach or gauges.
• If running an electronic tach be sure the tach input wire is not routed over the radio area.
• Some HEI distributors can send out interference. Be sure there is proper shielding on your firewall between the radio and the HEI distributor. In some extreme cases it may be necessary to relocate the radio body (motor) away from the firewall. (this is for vehicle with performance type of tuning)