Audio Systems: 94 Jeep radio interference-pulses- windshield wipers, jeep grand cherokee, power distribution system

Question
My infinity gold AM/FM radio (1994 Jeep Grand Cherokee) emits a clicking,pulsing sound in sync with the windshield wipers when the wipers are on the pause/delay mode and also pulses with the turn signals occasionally. Started about two months ago. Normally this happens on the AM band only. Also the power windows or the turn signal cause the same kind of pop, sometimes on FM as well.  One Best Buy store said offhand it might be the amplifier, but it seems from some of the answers it might be something else.  What tests can I do to find it and then fix it? What is probability that it is with an engine component and not a radio component such as antenna, amp, tuner, etc. ?  I put in a new battery to replace the bad old battery, but no change in the EMI.  Thanks.  

Answer
Greg,
It sounds like some kind of noise filter in the DC power distribution system has failed. Sometimes a ground strap that bonds the car frame to the body can break and noise can travel along the body and into the stereo system. You may want to try installing a 12-14 GA wire from the stereo to the fire wall. Also make sure by using an ohm meter to be sure that the engine is grounded to the frame with a very low resistance.  Installing a good DC noise filter in the DC supply lines close to the stereo may help keep out the noise. Have you added or changed anything just before the noise started? I have seen that on the inside of some stereos they have a small noise filter circuit that stops most electrical noise from entering the amp IC', it's possible that this filter has failed.

TOM,
T&D ELECTRONICS
tdeser@zoominternet.net