my 90 corvette shows discharge at traffic lights , stop signs or when the turn signals are on , dash lights will dim and signals will slow down !

I am on my third rebuilt altinator , I have added extra grown wires and still have not solved the problem , thinking of trying a 200 amp altinator , only other thing I can think of is a smaller pully but have no idea where I would get one ,

Any ideas all the altinator shops have closed up in our area !!

 

Most 20 plus year old wiring has tons of resistance that it didn't have when it left the Factory.

The CS130 Alternator generates about 25 to 30 amps at idle (at least that's what one member saw when they checked it with a clampon meter). The a/c is hogging most (if not all) of that so running on battery at idle is normal (in fact. GM chastised their Dealers years ago for replacing good alternators just because the lights happened to dim with extended idles. Their Service Bulletin went so far as to say that Dealers would not be reimbursed for replacing anything that tested ok when it got back to the Factory). You're not after higher cruise output, so when shopping, check idle output.

Heat is the enemy of the C4 alternator. Mounted close to the header and hood, it's difficult to improve anything. Vette Magazine or Covette Fever covered a few inventions back in '90's (yep, owners were having to frequently replace them even then) including a trio of fans mounted in the inner fender to help keep the alternator alive. I never tried it because I doubted that the puny idle output could handle an additional load (and I quit counting replacement alternators after the first dozen or so).

I found a .5 mm smaller pulley at a rebuild shop - didn't do much.

You might want to check grounds as the blinking may be just a poor one - but I'd guess the extra draw is simply overloading an already overtaxed system. You might also want to check connectors for voltage drop which is indicated by discolored wiring (a crappy connection heats it up). The HVAC blower motor - because it can draw up to 25 amps on MAX - is a good place to check. Ditto the cooling fans. Connectors are only crimped so if you find anything that looks burnt, take the weatherpak apart and put a dab of solder on the crimp.

Your dash Display might be as much as .5 to a full volt off. Feed is through the ignition switch and there's quite of bit of resistance between the contacts which you can clean up with some electrical cleaner. Drop the steering column for easy access to the switch.

www.alternatorparts.com has more info. Advertises higher idle output replacements. A member did try an "iceberg" model and burned it up within a week.

 

Well I am sorry to say this is what I was afraid of , so no easy fix , just a lot of checking connections , cleaning and soldering and looking for voltage draw.
At least you did not tell me to throw a lot of money at it just time and time I have so Thank you for that , will get busy !!

 

When our cars were new, the adage was carry a spare - especially if the trip was over 100 miles. That seemingly continued with the C5. Car & Driver had one of the first ones to test. The alternator blew somewhere in the Boonies (Tennessee if I remember right) and they were stranded for allmost a week as there were no rebuilds and anything GM had was being slapped on new production.

 

Joe, it's not exactly around the corner from you, but there is an excellent alternator shop in Starke, FL. Douglas Battery is the name. Probably about an hour and a half or so, up Rte 301.

 

Check the lug on the "Bat" terminal at the alt. It needs to be clean. Carefully inspect the lug to wire connection. Discoloration on the wire insulation at the lug indicates high resistance which = heat. Replacing the original lug & removing the first one inch of wire to get to clean wire is a suggested option.

Clean the "bat" terminal on the alt & insure the mount nut is tight. This is the nut that holds the insulator etc.

An additional 10 gauge wire from the alt "Bat" terminal to the junction block behind the battery will help.

For custom installs I use 8ga or double 10ga wire for alts with +100 amps.

FYI: My 90 has a sensitive volt gauge & it will flicker when the turn signals are in use.

GL

 

I have started cleaning up connectors , have battery out , need a few feet of vacum line looks like rotten from age and heat goes to the cruise control still works but good time to replace it .
Will keep looking and cleaning we did have the car parked on Daytona Beach for 5 years , I think my bones have rust damage !
Thanks for the tip Starke is just a nice cruise !

 

Well have not finished yet but this did really help

An additional 10 gauge wire from the alt "Bat" terminal to the junction block behind the battery will help.

Thanks for the tip