2004 Hummer Alternator Noise through RCAs

2004 Hummer Alternator Noise through RCAs Does anyone have a solution to the alternator noise coming through the RCAs off the $4,500 Eclipse Navigational HU? Things tested without luck: It's not the amps or power to them, its from the HU for sure - tried a bench deck and the noise was gone. Grounds are all to one place. RCAs are not it - tried running a set outside the vehicle with same problem. Put the deck on the seat, same problem. I'm thinking it's the alternator in this Hummer beast - too much curent? But the why does the factory equipment not make engine noise? Any thoughts/ideas would be much appreciated.

You can try a couple of things. Depending on the data bus interface you used, try installing 1 k ohm resistors on the negative return lines from the Eclipse head unit to the interface. The speaker lines with the black stripe in them should have them installed inline. Clean up the main battery ground from the battery to the frame at the left front corner on the bumper. It has a 10 mm bolt holding two ground cables to the front bumper and is know to be poorly grounded. Clean off the black undercoating and sand all contacts clean. Be sure to protect the connection afterwards with some sort of coating. You can also try a large polarized cap on the main underhood fuse block's power input cable. A capacitor of 40,000 microfarad or higher should do it.sparky

He posted this on CCA as well, I would still have a look at the factory radio ground wire that you are using and follow Dave's (Defro) advice on that ground wire. 60 ohms from the battery to the firewall is not a good thing no matter what.Top Secret, I can tell you but then my wife will kill me.