ford amplified system turn on pop

Hey guys,I am coming to you looking for help on two vehicles i have recently worked on.They are both suffering from the same problem.The first is a 2007 F-150 with the subwoofer amplifier and the second is a 2006 Mustang with the Shaker1000 system.I have installed Kenwood DNX5120 nav systems in both vehicles.The issue I am having is when the unit's power up I am getting a turn on thump.I am also getting a pop when the voice guidance finishes speaking.I have tried resistors,ground loop isolators all of the usual band aid's with no luck.I am using Metra 70-5521 amp integartion harnesses in both cases and have searched for missing amp grounds which are either not there or missing.Has anyone ever run across this situation and have a solution or fix for this problem.The biggest issue is that both of these systems are for the same customer.Thanks in advance for any help.

I am not familiar with the 70-5521 harness, but if you can tell me what from the radio connects to it, I can probably help you.

The harness is a 70-5520(new ford) with a separate amp harness,it includes a pair of RCA's as well as two amp trigger wires.I think I have found the answer to my problem though,apparently in my career in the mobile electronics business i have encountered my first two 5 volt amp turn on Fords.

you can use a voltage regulator from radio shack 7805 I believe is the part number. It drops 12v - 14.4v down to 5v.The wire I'm test'n isn't doin' what it's supposed to be doin'... I am so glad I printed that tech sheet, with the wrong info.

Do it right the first time... or I might have to fix it for ya

OK this is how i fixed the issue in an 05 mustang with the shaker system.......... get 2 identical resistors, put one end of each resistor towards the factory amp turn on, and the other 2 ends one going to ground and one going to the amp turn on off of the unit. that worked for me when i came across this problem on an 05 mustang. hopefully what i said made sense it worked for me, and for reference it was a mustang with a "shaker" system.A DMM is a beautiful thing.

MECP Advanced Installer Certified.