electrical woes

[Blackened302]

i'm unsure, but i think my alternator is going out--is there a way to tell for sure, aside from taking it off and having it tested?

the problem: anytime i have the headlights + fogs, radio blasting (stock mach460 system, no amp, sub, etc), or the a/c on driving around town, the car will die out.

at first i suspected the battery, but this happens when the car is running, so i figure it's more to do w/ the alternator.

ideas? thanks, gents.

 

[bill302]

have them test your charging system at a local autoparts store...oriellys does a good job they diagnosed a bad voltage regulator in mine which fixed my charging problem.they can test it while its in the car...

 

[HISSIN50]

Paul, Bill's idea is a good one. A dropped diode can show similar symptoms and a good dynamic test will check for this.

Otherwise, more info please. We'd need to know exact battery voltage with no load at 1500 RPM, and loaded at 1500 RPM.

When does it try to crap out? Only at idle or even while RPM's are up?

In general, even if your alternator shut off, the battery should handle the load for a little bit.

Good luck bud.

 

[Blackened302]

thanks, guys. a bit more info:

it'll only crap out at idle. only time i can run the headlights, fogs, a/c, etc is when i'm on the highway (which isn't very often anymore). otherwise, if i don't hold the revs by pushing the throttle a little, the car will sputter and die.

it never did this before (after the engine swap), as i could run my a/c and all lights at the same time while at a stop light.

 

[The Green GT]

Mine did that when i had my UD pulleys on.

Charging problems.

 

[HISSIN50]

Paul, Eric has the right idea. I went through a bit of this when I got the 94. I had my idle set to 635 RPM and with a full load at idle, the alt didnt like this. The clock and radio would shut off and then at about 10 volts, the battery light came on.

Revving it up t about 800-900 RPM fixed it. I simply reset my idle and that took care of it. Otherwise, you could also overdrive your alt. Just keep the Alt under 15000 RPM.

If the alt does ok at RPM, this is where I'd start.

Good luck bud.

 

[Blackened302]

hmm.. i wonder...

i don't have the Mac u/d pullies in yet (waiting on the radiator to install them all at once), and my idle is at 888rpm right now.

i'd think that's high enough of an idle speed, and it was set at 750 for a few weeks after the engine swap when everything was working fine. <--yet another thing that leads me to think the alternator is failing.

is there a way i can test my voltage regulator?

also, by overdriving my alt, that means i SHOULD install the smaller pulley the kit comes with, correct?

 

[HISSIN50]

Paul, if holding the RPM's a little higher than 888 helps, the Overdriven pulley might work for you. Not knowing how small it is, I wouldnt say to install it for sure (for overrev concerns).

I'd go back to Bill's idea because we know something has changed with your alt and that something is failing. The regulator is tested in part by a dynamic alternator test. Otherwise, I just have to run down the flowchart of diagnostics (voltage and resistance checks).

 

[Blackened302]

alright, i'll try and have it tested over the weekend.

thanks a lot, gents.

 

[mo_dingo]

You may also want to check your connections at the battery, engine/motor mount grounds, and your main alternator connections.

A DC amp clamp on the alternator's positive wire going to the battery terminal will tell you how many amps the alt. is putting out. You may also want to check your current draw to the system at idle to see if the alternator is keeping up.

Finally a specific gravity test on the batteries cells will tell you if the battery is any good (has to be fully charged for this test to be accurate).
Scott

 

[drakesdad]

have them test your charging system at a local autoparts store...oriellys does a good job they diagnosed a bad voltage regulator in mine which fixed my charging problem.they can test it while its in the car...

Paul
I stopped by Auto zone just today....took the fam to dinner...and when I started it up the batt light was on and the volt was all the way down...
went over to AZ and they wheeled out the tester and I watched it come on the screen.."dead battery" ....changed the batt and the light stayed on.....went home and pulled the alt......and it failed before the test was complete.......
guy at AZ didnt approve of my UD.....but I still made him switch the pulley over to the new one......I got the lifetime warranty....so I'll keep my UD's on and replace the alt as needed....
good luck brother

 

[earleys94gt]

When my alternator went out, my battery/charging light came on and stayed on. Once I put on the new alt. it was all good. One thing to think about, if you have an stereo system, you may need a better alt. than stock.

 

[Blackened302]

thanks for the comments/suggestions, guys.

scott--i'm assuming you can get a DC clamp at the parts store? i have a multi-meter, if that'll do. i'll also double-check the engine grounds and connections at the alternator, battery.

mr. drake's dad--i'm worried because i have yet to put on the u/d pulleys. i want to take care of this before i do so i don't wind up making the problem worse.

earley--funny you mentioned the battery light. noticed mine on today w/ the key in the "run" position. also, the only aftermarket piece in my sound system is a pioneer head unit. other than that, i'm stock mach460.

i stopped by Advance today to make sure they tested the electrical system while it's inside the car, though i was in my fiance's scion and didn't have a chance to go back in my car. good thing it's right across the street from our apartment. gonna try and get it done tomorrow.

thanks again for all the help, gents.

 

[HISSIN50]

FWIW, the battery light should come on for a prove-out with the key in the run position. 12 volts is sent from the ignition switch to the light and then to the I terminal of the regulator. When the alt is over or under charging, the regulator grounds the circuit, illuminating the battery light. When things are copacetic, the regulator ungrounds the circuit and the light goes out.

 

[Blackened302]

thanks for mentioning that, JT. i have noticed that when the car dies out at a stoplight, the battery light does come on then, too.

guess that's a hint that something is in fact not good.