I have a red signal light that keeps blinking in gp328 any ideas?

A blinking red light can be a sign of the radio picking up radio frequency waves (RF) on your same frequency or a nearby frequency. There may something transmitting in your area which is causing the blinking light, or you may have another radio which could be stuck in transmit. One way to check this is to take the radio to a different location and see if the blinking still occurs.

Next, the question would be, does the radio function otherwise correctly? If so, continue to use the radio and do not concern yourself with the light. If the radio does not function properly, they you should send it to a qualified radio repair center for service.

Best regards.