Sporadic Charging Dummy Light - Loose Connection?

[jstluise]

1994 Nissan Sentra LE

A few weeks ago, my battery dummy light (and failsafe brake dummy light, since they are on the same circuit) started coming on every once in a while for a few seconds. Some days it would not do it and and others it would do it once or twice a day, for maybe a couple seconds or maybe stay on for a minute. Very sporadic. It seems to come on when the car goes over a bump, which seems to indicate a loose connection, but it also come on just driving on a smooth road. When the lights come on, there is a drop in power for sure (lights, fan, etc).

Now I am just looking for some direction on what actually can cause these dummy lights to come on. I've checked all the grounds that I can find, and all are tight and clean (I haven't taken them off, but they look don't look corroded). Battery is good and connections are good there also. I've unplugged some of the connections for the alternator while the car was running, but I couldn't get the lights to do the same thing.

I did replace the alternator maybe 8 months ago after it went out...the lights actually came on the same but stayed on, and I was able to diagnose the problem (bad alt). So I replaced the alternator and everything was good up until a few weeks ago. Could it be the alterator?

This problem is frustrating since it doesn't do it all the time...so diagnosing it is going to be a challenge until it does it more frequently or stays on. Any ideas? Maybe connections to check that would be causing this problem if they were loose? I really can't take the alternator in to test it since it doesn't do it all the time.

Any help would be appreciated! Thanks!