SES light

check engine light is on and wont turn off, about a week and a half ago i had to replace my coil pack, all is good, light shut off without a problem, about two days ago it turned back on, i checked under the hood and see no problems, all the connections are tight, the only thing i see is that the plug wires dont seem to be sealing well to the valve cover, i dont think that is the problem though, cause now when i turn my lights on or use my turn signal, the radio shuts off for a second and turns back on, i also checked all my fuses, the only thing i can think of is its not getting a good connection from the battery or the plug wires, (had to get new ones, they are oem), dont carry enough charge to keep everything running properly, but i dont see how that could be the problem as they have nothing to do with my lights or stereo......... any ideas????????

You're on the right track, something isn't grounded properly or the system is gorunding out somewhere. Check all connections, clean all corrosion and oxidation, make sure your battery is in good order. Cold weather leads to electrical problems stemming from a bad battery. But you know all this, right

yea, i figured it has something to do with the battery somewhere, im off tomorrow so i think ill spend a little quality time under the hood tomorrow.... i think i know what it is now........ thanks for the input spydergs........