Was driving along and noticed a drop in all electrical power. Lights were dimmer, stereo wouldnt push subwoofer etc. Took it to Checker to test alternator and they say it was no good. Replaced the alternator but still no change. Voltage is only around 12 when running. I have no idea what else it could be. Any ideas?

 

been away for a while so i'm not sure of your dak, year, model etc. what is the output of your alt and how much power is your sound system drawing, you may have blown the computer voltage regulation. i don't think in 30 years i've come across a battery failing that fast, they usually go down hill over a period of time. never had it happen but i've also heard of rebuilt alts not working out of the box. the last thing i can think of is a short somewhere, if your sound system was not installed properly and you have a wire that is not fused that should be you may be drawing way too much power.
there's a reason i hate electrical problems! but i hope that helps guy.

 

Its a 1990 w/3.9.Its a 90v alt. Truck has no power accesories. I'm going to take the alternator in for a bench test after I type this. I pray the new alternator is bad I really dont want to go around the merry go round with this truck and the wires again. The amp is a 500W swap meet special, of course I wired it straight with no fuse, I figure the fuse in the amp is supposed to blow if something goes wrong but I know nothing. Will post an update as soon as I get back.

 

my 89 3.9 had a 75 amp japanese model on it and cost 200 bucks rebuilt, i didn't know at the time but i could have replaced it with a 90 amp chrysler model for less money. i think you can get a 120 amp for not much more than the 90, that might be better to run the stereo system you have on.
don't worry about the installation, just fuse all the power (red) wires and you should be good. i've installed a lot of stereos over the past 30+ years and i still make mistakes. have i mentioned i hate electrical problems.
good luck guy!

 

Well the alternator is good I guess I'm totally screwed now. Any ideas would be helpful

 

fuse your amp. make sure its properly grounded. and make sure that the speaker wires off the amp arent touching, this causes the amp to short and draw more power than it needs. other than that, i have no clue, you would have to go through different electrical tests to find the short

 

I took the amp out just to eliminate it.there is a problem between the battery and alternator I guess. Time to spend countless hours figuring out the problem I guess.

 

the only thing i can think of between the batt and the alt is a few wires and the computer. check every possible connection, make sure there good, if they are then have your battery checked to be sure, although i've never heard of a batt quitting that quick there's a simple test you can do to check. turn on your lights at night then get someone to start the engine, if your headlights go out during the starting process at around 60f and it's slow to turn over you have a weak battery. if they just flicker and starts normally, then the batt and connections are are probably ok and i would look at the computer voltage regulation. a bad battery won't take a charge no matter how much voltage the alt. puts out and could read low.

 

Doesn't the 90 still have an external regulator.My 88 does,it's in the middle of the firewall.If it does check that it has a good ground to the firewall.

 

Well I havent been able to do anything with it. Connections look good and I'll do the light test at night on Monday. I ordered an external regulator should be in on Monday. Although I'm not even sure it has an external but they had the part for the year. Will post an update as soon as I get it on.(If I can get it on LOL). I'm not too sure its the battery it sure turns over and starts right up about 2nd crank. But I'll pull it and have it tested and checker anyway. I just love electrical problems phhhtttttt.