I drive a 98 Z28. The head lights and interior lights dim when I apply the brakes. I can see the voltage drop on the gauge in the cluster. The lights also dim when I first start the Z and the weather is cool enough that the A.I.R. pump (pumps air into exhaust in cool weather to reduce pollution, read it on this site) will come on for short periods of time (less than 1 sec) at five second intervals for a couple of minutes. Lights will also dim and check gauges light will come on (less than 1 sec.) when cruising down the street or highway without applying the gas. Again the voltage meter shows a quick drop and recovery. First, is it normal for that A.I.R. pump to come on and off at short intervals after running at initial startup? Second why do the brakes cause such a drop in voltage? Is this as simple as a battery or alternator? Your expertise is much appreciated.

 

id say alternator, if it was the battery then the alternator would be charging high to make up for it. as for the airpump, i dont know, mines in the trash, lol.

 

If you have a volt meter with the car running; at the battery it should read around 13.8-14.2 volts if atl is working properly...

 

Just about any auto parts store will check alternators and batteries both in and out of a car to see if they're bad.

 

You may want to read this, because replacing my alternator and battery did little to help this issue for me. I'm *still* looking for a reason.

http://web.camaross.com/forums/showt...hreadid=219558