Yesterday, my roommate (who's truck it is) tried to replace the stock solid-state radio in his '88 F250 with a questionable CD player/radio that was ripped out of a Mazda (aftermarket). We searched around, eventually found a wiring diagram, and spliced in the new player. Turns out it was dead. Fair enough, we thought it might be.

BUT. Then we went to splice the stock radio back in, and something ain't right...
We get white noise through both speakers, balance (bass/treble), and r/l fader are working, so there is power to the unit. However, actual stations won't come in and the clock won't come on.

Also, he has always had some sort of loud, annoying buzzer that goes off for a few seconds whenever he starts the truck, this is now interfering and coming through the speakers.

What the hell could we have done? Did we fry something? All nine wires and the antennae are connected exactly as they were prior to removing the radio. He refuses to get a manual for the damn thing too, are there any links online to good wiring diagrams?

Any help would be awesome, thanks guys.

 

There is a radio noise capacitor mounted to the coil on the driver's side valve cover.

 

Thats what that cap is for ? How does that choke RFI ? I get how ferrite works but not a cap...

 

I'm not sure how it works, but I think I read you only need it for the stock radio. Maybe it got damaged somehow.

 

Is it just a Ferrite bead? I dunno how we could have damaged it, but electromagnetism is ridiculously strange... Anyway, if we removed the filter and stuck in a working aftermarket unit it would then supposedly work. Assuming we somehow mussed it all up.