Stumped Head Unit Issues

Yes, that could be the reason why there is no sound.

this is just my opinion.

a bypass would be good if your just replacing the head unit. but if your planning on running any other equipement (ie amps, eq, crossovers etc) i would run all new wiring for the sytem. you never know what your gonna get into and if you run all new wire you know what is what and know what is actually in the sytems circuit. some people get it to work with the factory wiring but have problems with factory x-overs and amps that they didn't even know where there. and then you find yourself trouble shooting for hours on end wishing you did it in the first place. if you want to tap into the factory components you might want to take it to a pro installer if your not one. another problem you might run into is this.  your purchased it used and clipped off.,but you actually don't know if the factory components are still there or in working order.

my advice-start new ;)

First off, no matter how much you look you will NEVER find rca's at the OEM amp. That gray plug at the dash is the input to the factory amp. You can use an intergration harness if you just want sound. However, if you wish to bypass it, or it doesn't work you will need to.

The "bypass" which is aka "ford amp eliminator harness" will work however if the gray plug is cut at the dash you can use one side of the bypass harness to grab all the speaker wires. Power, constant and ground will be at the dash already.

One of the eliminator plugs will have a small end and a larger end. Cut the small end off, splice 4 speakers wires to it, and run it to the dash. If you plan on adding an aftermarket amp then you will run rca's to the back.

Hope I helped clear this up for you.