I'm a new Corvette owner. I have a 90 Roadster Convertible which I'm going through replacing a few neglected issues as well as a detailed cleaning right down to using q tips. The interior is near mint after spending alot of time on the sport seats and a very decent exterior. Today I changed the battery. Seemed like the old one wasn't holding a charge although I kept it on a trickle charger. After installing the new factory replacement battery I just had to take it for a spin to break the winter blues. It was dark out and I noticed that the head lights as well as the dash lights seem to fade. Even seems to happen when I stepped on the brakes. When I gave it throttle the lights seemed to get brighter. The voltage gauge hovered around 16 volts while driving but seem to adjust according to the throttle action. I brought it back and put it on charge. The new battery indicates that it is 95% charged. I did notice the fading on the dash lights prior to the new battery and thought that the replacement might take care of it. So... not sure where to go from here. The car seems to be an education but I'm so glad that I'm finally a Vet owner. Wonder if I have an alternator problem, not sure what to check. I did notice on another posting that I should check between the (+) and (-) posts and the draw should only be no more than 50 ma. Any help for the newbie ??? Please.......... Thanks

 

sounds like the alt. Most auto parts stores can test it for free on and off the car. Check to see if the belt is slipping also.

 

Hi

I had that problem on another car, not my vette. It turned out to be the alternator. I had the charging system checked by my mechanic and he said the alternator was not charging the battery and the battery was taking the load from the lights. So, in a nut shell, my lights were killing the charge on the battery. If your not mechanically inclined, take it to your mechanic and tell him what you just told us. If you are, check the output on the alternator. Could be the alternator or it also could be a voltage regulator. You don't want to replace an alternator only to have it be the voltage regulator. Good luck. Let us know what it was.

 

OK I had my alternator checked today and all is well. I did notice that when I pulled it that the alternator that the connector for the bat wasnt the best but it was still a connection. Any thoughts on where to look next? Could I be having puter issues. Thought I would have corrected this with either the battery or the altenator. HELP!!!

 

Ok, well.... hmmm, I wonder if it could be a short somewhere else in the charging system. These are sometimes hard to find. A short would kill your battery if the car sat and there was a draw somewhere. but the dimming of the lights sounds like the alternator. Wiring and charging systems are one of my weak points. I don't know if these cars have a voltage regulator. Ok, I just called my mechanic. He says that two things could be wrong. I know you said that you had the alt checked. he says there is no remote voltage regulator on these cars. It's in the alternator. So if that's bad, your lights would brighten and dim. He also said that you could have a ground strap loose. there are these ground straps that go to the frame. Don't know where they are. Those are your two possibles. If you are possitive that the alt is good and that this voltage regulator inside the alternator are good, you need to look in a book to see where these ground straps to the frame are. I know this is confusing but it's confusing for me too. As i said, wiring and charging are one of my many weak spots.
Let us know what you find out. I am as curious as you are.

 

Clayton, Thanks. I've been talking to some guys at the station and they are leaning towrds a ground issue. The altenator does have the voltage regulator built in to it. New battery, good altenator, sounds like something not connected well. I also going to look into the connection on the altenator and see if I can get a better connection on it. Anyone with thoughts on the location of the grounding strap or straps? Thanks

 

on my 86, there is a bolt in which several grounds connect; its on the driver side, kinda by the oil filter. you can only get to it from underneath. just follow the negative battery cable to wear it connects to the chassis.

 

If your battery is truly charging 16V, that is to much. When you had your alternator checked, did the load check it or just voltage check? A good load check, around 200 amps, will really reveal the health of the alternator. Again, 16 volts may be misleading, because the either the internal regulator is bad, which case you will eventually burn up your battery, or as stated before, bad connections. A good alternator should not drop to more than around 10v under a 200 amp load. Good luck [8D]

 

sometimes when any electrical unit is exposed to the elements, the contacts on the molex connectors become oxidized, causing all kinds of weird problems. try spraying the molded connector with a contact spray one of the best is called de-ox-ide and i believe you can get it on-line at any major electronics distributor

 

Mech259 is right. 16 volts is high. It's possable that the regulater is putting out too much and the dimming is when it comes into the "normal range" of operation. Say 12.5 to 14.5 volts.A prolonged reading of 12.5 on the lowside and anything over 14.5 is abnormal.

But we all know that the gauges are not allways acuate. Maybe check your voltage with a multimeter to be sure of the dash reading.