Vehicle: 2003 Ford Explorer Sport with stock radio/tape/cd player. Went to Mossey Ford and they said radio was working within specs. (Yeah right). On weaker am stations found radio almost unusable because of ingnition noise that followed the engine rpm but almost went away at idle. Pulled antenna mast and cleaned with steel wool. Did not help. Pulled radio and put a 1 microfarad cap across 12 volt to ground leads into radio. Also pulled all connectors and reseated. Also tried a filter cap across the 12 volt to ground on the alternator. Nothing helped.

 

did you put a noise filter on the power lead? is the factory one still in place?

 

There is no external factory filter, only the one internal to the radio which I thought might have been bad. That is the reason I put the 1 microfarad capacitor (filter) across the power leads into the radio and that did not help.

 

I pulled the factory radio forward using the Ford factory tool and then removed the antenna connector from rear of radio. The connector was very secure, not loose at all. Using ohmmeter I checked the inner conductor to antenna and found continuity normal. I then checked the outer connector (shield) and found no continuity to vehicle frame. I removed the antenna base plastic cap and checked continuity between the antenna base and the frame and found no continuity, meaning the antenna itself was not being shielded by the steel body from the ignition system, nor was the steel body acting as a ground plane for the antenna. I replaced the pan-head sheet metal screws with screws that were one size larger and again measured continuity to frame. Continuity was restored. Reconnected the antenna to radio and found a huge improvement in reduced ignition noise and am sensitivity. Though there was still a little ignition noise on the weakest out of town stations it is now definitely usable.