pingdashf

I have had issues keeping a battery charged in my vette since I bought it a few years ago. I've replaced the alternator once based on the local GM shop's findings. I've added the MSD 6a to the car as well, so I guess its possible I messed up some wiring there, but the short version of the story is that last night I got stuck driving home at night with no headlights/tailights. Fortunately I live in a mostly lighted area and traffic was light, but the car has gotten to the point that I can't drive it due to its electrical problems. Nothing electrical in the car will work after 15 minutes of driving including blinkers, radio, windows, etc...

So, now I begin my summer project. I need to learn anything and everything there is to know about 1974 Corvette Electronics. I haven't started research so I'm sure there are some good posts here and on corvettefaq, but I just couldn't wait to whine. Anyone got any clue how I track down electrical problems? I don't really even know how to use a voltmeter :)

wcsinx

:confused: Is the car still running after 15 minutes of driving? Is the battery dead after 15 minutes of driving?

You should be able to start the car, and pull the battery and have everything still work running off the alternator. (Unless there's something kooky I don't know about C3 electronics) :confused: :confused: :confused:

multifast1

If you're serious about tracking this down yourself and fixing, I'd suggest getting a shop manual for that year.. I just bought a used one and haven't gotten soooo much out of it already. I've seen some great posts here already on how to track down electrical drains in the system using a "process of elimination" type method. Use the search function to find more info.

Using a multimeter is cake. You can even doa google search if you want and find some good detailed info on how to use it for checking continuity, voltage, and current draw. You don't need anything fancy either.

Unless you plan on doing tons of research and spending many frustrating hours... I'd suggest taking it to an "expert". The $ you'll pay for the service may be worth saving the headaches. The problem with that is finding the right place to take it. Good luck.

stpman

:iagree:
If you want to learn all there is about you 74 then get a shop manual, it contains all of the wiring diagrams for your car. Most of the supporting vendors cary them.

oh yea I have the 74 manual and a wall size wiring diagram if you have any questions you can IM or e-mail me

Steve :steering:

pingdashf

Then maybe my alternator is what is bad. Or it could be the wiring to the alternator, I dunno. I need to figure all that out. I have to jump the car to start it, and when I do, all electronics will work great for 15-30 minutes of driving, but after that nothing works.

pingdashf

Shop manual has been ordered...

Boofers

You can pick up a cheap voltmeter for a few bucks. To check if your alternator is working:
1) Set your voltmeter on volts DC.
2) Connect the black lead of your voltmeter to the ground terminal of your battery.
3) Connect the red lead to the battery positive terminal.
4) With the car off you should have between 11 to 13 volts DC.
5) Start the car and rev it up to around 2500 RPM a few times then let it idle.
6) With the car running you should see this voltage increase by about 2 volts for a reading of between 13 and 15 volts DC (basically to charge a 12 volt battery you have to give it more than 12 volts).
*If the voltage does not increase with the engine running then your alternator is not charging your battery. :cheers:

Z-man

My first guess is a bad (or going bad) alternator. Once it's running, your alternator should have enough oomph (technical term) to run everything electrical AND keep charging the battery...

It could also be a loose belt on the alternator which is making it spin too slowly - same symptoms.

Good luck... :)

wcsinx

I'm gonna say your alternator is bad. I bet if you pulled your battery after jumping, nothing electrical would work and your engine would either die or start running like shiz.

mike229

Carson,

Im having the same problem after a new battery and alternator - since I also am a novice mechanic, I am "taking it in" to get fixed - Ill let you know what the problem was if you are interested...

Something is drawing the battery down while the car is off and I just cant find it...

marshrat99

I've had the same problem with my 79 for the last two years. The battery discharges after about a week of non-use. I took the simple (maybe bubba) approach and installed a battery disconnect. :cheers:

GATOR454

I sent you a 74 wiring diagram.

There is a circuit that runs from the alternator to the junction block on the drivers side fender wall then to the starter solenoid.

The junction block also feeds the fuse panel (courtesy light, lighter, clock, tail light, hazzard and stop lights) and after a junction to the horn relay, steering column ignition switch, and light switch. It also feeds the ammeter through a different route.

The other fuses in the fuse panel (A/C, Dir Sig, TCS Solenoid, Wiper and Radio) are fed from the ignition switch.

The only apparent connection to the battery is through the starter solenoid.

The connection to the ignition system is from the ignition switch. This circuit also feeds the gauges fuse.

O.K. with all that said. Since the car still runs when you loose power then I would suspect the wire from the wire junction on the inside of the car (not the junction block) to the fuse panel, or a problem with the fuse panel itself.

When the car is running the alternator and battery are as one. If you loose the alternator then the car would run on battery power until the battery ran dead, but everything would work until then.



[Modified by GATOR454, 5:28 PM 5/12/2004]

brooksman9

[QUOTE]I sent you a 74 wiring diagram.[QUOTE]

Now that is service :yesnod: