88 charging issue? not sure if alternator bad or something else?
 

Hello I have a 1988 convertible. I am having a charging issue. When I let the car sit for a while and go to start it the starter sounds sluggish and sometimes makes the clicking sound and eventually starts. when driving the volt gauge sometimes shoots up to like 14 or 16v! And when I press on the brakes at night with the headlights on the volts drop down very low to like 10 And my lights dim very much. The alternator also feels like ridiculously hot to the touch. This morning I went to start the car and it was dead so I jumped it with another car and I got it started. I checked the battery and alternator with a meter and it's reading 13v. I just want to make sure my problem is definitely the alternator and not something else. What do u guys think it could be? I have been reading other threads on here about btn fuse and L wire (which I'm not sure what that is) but I'm feeling a little confused.

If you've not done the 4-state test in the Second Gen FAQ, do so and it will tell you everything you need to know. At the battery terminals, check the voltage with the key OFF (12.6v is normal for full charge), Key ON (12.5-12.6),cranking the engine (10.0+) and with the engine running (13.5-15.0).

By your description, it sounds like the alternator has crapped out (under 13.5 when running) and cooked the voltage regulator (spikes to over 15.0v). Now would be a good time to upgrade, my recommendation is to go for a 130A Taurus Alternator. They're common, easy to find in a junkyard and I've never seen one fail from being overworked yet. The only time I have personally seen one fail was when the voltage regulator gave out after 20+ years and they are rather easy/cheap to replace. When that happens, it pulls a Jeremy Clarkson [POWAAAA!!!] and can pop a 150A breaker through 20ft of 4 gauge cable without breaking a sweat.

Plus, it'll feed absolutely ANY E-fan you want too :nod:

Thank u for the reply that was very informative. I am not able to find that 4 state test. I did look at the electrical section of the FAQ not sure if that's what u meant. And ok the Taurus alternator seems like the best choice but if I were to just replace it with a 70a FC alternator would that go bad quickly or last me another couple years? I ask because I see that with the Taurus alternator ther is some custom work that needs to be done and I am sure my mechanic can do it since he has owned a turbo2 but Idk if I want to order extra parts like the pully adapter and have him make a custom bracket. I'd rather him just take off the bad alternator and pop in a working one.

So I just went to try to start it and its dead again just making clicking sound. So its safe to say my alternator is done correct?

Edit: I just checked the amps with the key on and off and Its reading 9v

The alternator charges the battery but does nothing for the battery when it is just parked.

Do u think my problem could be the battery? Sorry I'm not very mechanically inclined so I am a little lost at the moment.

If you charge the battery and it dies just while the car is inactive then you either have a problematic battery or an amperage drain.

Ok that makes sense but the fact that my battery volt gauge spikes up and drops down leads me to believe my alternator is bad would u agree? Or could a faulty battery also cause that?

Well the obvious is the obvious as the gauge should not spike but it could be the gauge and not actually the alternator. The gauge runs off of the meter fuse so if the voltage from this fuse stays steady when the gauge spikes that would indicate that the gauge is problematic and not the alternator.

Sounds like the voltage regulator. I had a similar thing happen and the high voltage ended up destroying the battery (split the case, acid everywhere)!

In looking back at things, an alternator can drain the battery while the car is not being used. If the battery were fully charged and an amperage drain test was conducted and it showed evidence of a sizeable drain, with the voltage output cable to the alternator then disconnected, if the amperage drain stopped then the alternator would be the cause.

Thank u all for the help. The alternator is being rplaced and hopefully the issue is solved.

So I had the alternator and battery replaced and it has been starting and running fine..but as of recently when the car idles I hear a low pitch buzzing/rattle noise and my idiot lights all come on! Its kind of like when u stall the car and the engine cuts off and all the lights come on except my car keeps running. When I rev the engine or start driving the noise and lights go away. I have been reading that all the lights coming on means the alternator is going bad...but this is a replacement alternator that I just bought I dnt think it is failing already?! During all this my voltage gauge seems to be reading correct volts no dropping or spiking up like before. What could be the problem guys?

If the idle speed drops too low that could possibly cause the lights to come on or the alternator warning light relay in the CPU might be problematic. Does the sound you hear come from the lower dash area or from the engine bay?

Thanks for replying. And the sound comes from the lower dash area. it hasn't really done this in the last two days. So Idk what's going on. I've noticed that this car does that a lot, something is acting up and then kinda fixes it self for a while lol

Sounds like the relay in the CPU. The relay tells the idiot lights to come on. The relay is triggered by the White/Black (not Black/White but White/Black) wire coming from the alternator's two wire plug. W/key to on and the engine off this wire has a ground signal on it which activates the relay and causes the lights to come on. The W/B wire also has a ground signal when there is a problem w/the alternator or otherwise the W/B wire has voltage to it w/the engine running. Just because the alternator has been replaced does not guarantee the unit is good as many fail right out of the box. There is a possibility that the W/B wire is briefly grounding out when it comes in contact w/metal if the casing on the wire has worn away. Other than that, you could take a multimeter set to DC voltage and connect it to the W/B wire (Red lead) and the Black meter lead goes to the Black wire in the same CPU plug (this would be the largest plug at the CPU) and see what the voltage reads. With the car running and everything okay the meter should read close to 12 volts. When things go wonky the voltage on the meter will drop close to a few volts or lower.

Thank u for that response I will check that out. I also have another question. today I drove the car to work and started fine and then after work also started fine i stopped and grabbed something to eat at Wendy's and after that I went to start the car and it wouldn't start I had to put my foot on the gas and it was able to start then I stopped at the bank for about 20-30min and again the same thing except this time I had to pump the gas pedal to get it started. I drove home and waited about an hour to see if it would do the same thing but this time it started right up. So it seems like it was flooded the previous times correct? Does this mean I need a rebuild? My car has 127,000 its my daily.