CamaroZ28.Com Message Board - 4th Gen wiper motor rattles- vibration

I have a 1995 Z28, all stock with just over 86k original miles. The pulsemodule went out and I replaced it. The wiper motor itself is original andseemingly works fine. However -- thewiper motor vibrates / rattles; but, only when the engine is running. It is anelectrical induced rattle. I traced this down one afternoon. At first I thoughtit was the linkage or spring around the top of the motor where the linkage ballsnaps over. I had the car idling and as soon as I plugged in the electricalconnector, there was a slight vibration felt in my finger tips. The wiper arms don’tmove. Unplug the connector - novibration. If the engine is 'off' and the key in the run position, novibration. If I pull the fuse, no vibration with the engine running or not.Nothing can be heard outside of the car but inside it sounds like a like a tin canwith rocks type of rattle. With the engine running, and with the wipers ‘on’ orin ‘delay’ mode; thus, any position where the wipers are not 'parked', there isn’ta rattle noise.

I am wondering if there could be a bad ground with the distributor, fuelpump, or injectors.

Has anyone experienced this before? Ihave been searching but have not found anything this unusual.

Thanks in advance.