Maybe it's taking some time for some Caps to discharge and that's where your 4 sec. are coming from???
While awaiting my screen repair, I installed a Clarion FM modulator in my car so that I can listen to my music over my radio. I'm stealing the power from the radio to power the FM modulator. I did this by inserting clips on the (+) and ground wires coming from the back of the radio. One thing I noticed since I installed the FM modulator is when i turn my car off, my radio stays on for about 4 seconds. This didn't happen before. The FM Modulator has an on/off switch, so i tried turning the modulator on and then turning the car off, but this time, the radio shut off right away. Does it make sense that the modulator is storing power and powering the radio after i turn the car off for those 3-4 seconds? Also, does anyone know if it's "safe" to keep the modulator in the on position all the time? Thanks.