Engine and battery light keep comming on

mccurdy · 06-28-2008, 01:41 PM

I'll be driving down the freeway, and the brake light and battery terminal light keep going on, then off and random times. Like, the 2 lights will be off, then ill shift, and suddenly they come on. I look back 5 minutes later and they're off again.

I have to drive 4 hours next weekend so im a little concerned. Any ideas guys?
I don't see any leaks and my rear pads are getting a little low, but shouldn't throw a brake light or a battery light. Both lights come on simultaneously.

is going on with my car?

Sorry, i didn't mean ''engine'' light in the thread title, i meant brake light.

EagleTSIawd · 06-28-2008, 01:48 PM

check to see if your alternator is working properly. turn on the car then unhook one of the battery terminals while the engine is still running. the car should stay on, if it doesn't then you have a bad alternator.

turboglenn · 06-28-2008, 04:05 PM

Yea, that's what happens when the alternator stops putting out voltage, or the belt breaks. Being that yours is random, i would look for loose or corroded terminals, a loose wire at the starter, and otehr faults in the connections. You can test by doing teh battery removal test, but i'm not sure that works on our cars (certain newer cars need the battery to complete a circuit, not so much for it's voltage and will die even if the alt is good..)

I tried it once on my car when the alt was only getting weak and the car wouldn't stay running without teh battery hooked up.. But there was something wrong with the alternator that time. It was only putting out about 11.7 volts with the accessories turned on, and only about 13.2 with nothing on, so i can't base anything off that test. But, i wasn't getting any lights from the alt messing up that time. I would just notice teh tach jump around at night with the lights and heater adn turn signal on, the tach would jump with every click of the signal relay.

mccurdy · 06-28-2008, 08:40 PM

i notice if I gas it, the 2 lights will turn off.

I did just recently swap out my spark plugs. Someone else said it could be spark related, but i wasn't sure.

My battery i know is crap too. How do i remove the terminal while its running w/out it shocking the crap outta me?? Also, which terminal do i disconnect to test this?

kanderson · 06-28-2008, 08:44 PM

I'd disconnect the negative side so that if it touches part of the body/frame/engine it won't arc. Will someone confirm this?

Also, its only 12 volts, it won't hurt too bad. I mean, it'll wake you up if you're falling asleep... : )

turboglenn · 06-28-2008, 10:16 PM

Just undo the negative terminal and as long as you don't purposely touch a positive terminal or wire you will not get shocked. But if you pull the positive terminal and are touching it and touch any part of the car that has bare metal you will feel the shock a little (it's honestly not bad from a DC car battery if you get shocked in the hand..not sure about other areas though :P )

EagleTSIawd · 06-28-2008, 10:28 PM

I always undo the positive because its the easiest to unbolt for me, and because i like to see the cool spark haha...

you could also read the volts on the battery with a voltmeter, i would do this with the car off, it should read 12+ volts anything less could indicate a bad battery.

mccurdy · 06-28-2008, 10:40 PM

well my SAFCII reads anywhere between 11.9 volts and like 13.6 or something when driving. When i gas it, the volt readings go up, but when the RPM's drop, they volts drop down to like 11.9.

I've never seen 14.4 or anything like other people claim.

turboglenn · 06-28-2008, 10:50 PM

Quote:

Originally Posted by mccurdy

well my SAFCII reads anywhere between 11.9 volts and like 13.6 or something when driving. When i gas it, the volt readings go up, but when the RPM's drop, they volts drop down to like 11.9.

I've never seen 14.4 or anything like other people claim.

Yep, your alternator is shot...replace it and you shall be a happy man again, or at least able to move on to the next DSM related issue in your life

mccurdy · 06-28-2008, 11:37 PM

i heard a crap alternator can rob you of serious power. This true?

Like, if people switch out pulleys for aluminum lighter weight ones, then it stands to reason an alternator not providing enough power can limit your power applications.

EagleTSIawd · 06-29-2008, 12:03 AM

running on battery would only give you a while of good solid current (if the battery was fully charged) then as it keeps loosing life you would probably feel the loss of power.

i would never put one of those aluminum pulleys anywhere except on the crackpulley. when i was in highschool i had this integra and i installed all the AEM pulleys including the crank. That was a bad idea because it made my alternator and power steering spin real slow

Defiant · 06-29-2008, 05:34 AM

Your alternator's shot.
Don't disconnect the battery of a running car if it was built after 1973.

phunny · 06-29-2008, 06:50 AM

Quote:

Originally Posted by Defiant

Your alternator's shot.
Don't disconnect the battery of a running car if it was built after 1973.

Why not?

turboglenn · 06-29-2008, 10:13 AM

Quote:

Originally Posted by phunny

Why not?

I'm sure Defiant has a much more technical or accurate explantion, but i've been told that on some cars you can actually fry the internal regulator in the alternator by pulling the battery termnal with it running. That's why in an earlier post i had mentioned that some cars need the battery to run even if the alt is good because the battery completes a circuit when connected.

mccurdy · 06-29-2008, 10:55 AM

how the hell do i test it then w/out dropping it?

if the alternator is dying, its still driveable for now right? will it eventually fully die? if so, will jumping the car still make it start up?

turboglenn · 06-29-2008, 11:08 AM

By looking at the voltage at the battery terminals with the motor running.. Put a voltmeter on the battery terminals with the car running and see what your "baseline voltage" is (the volts with car running all lights and stuff OFF ) then turn accessories on all at once, lights, heater, wipers, radio etc.. if the voltage doesn't rise back up to your baseline after a few seconds for the regulator to adjust then your alternator is bad.

I.E. your car puts out 13.5 at idle with no lights on. You turn lights on and the voltage will drop down at first, if it doesn't rise back up to 13.5...say it stays at 12.2 or something, then the alt is bad...since our regulators are internal on our alternators you must replace them as an assembly or rebuild it.. replacing is easier and most of the time they have warranties when new.

mccurdy · 07-02-2008, 11:18 AM

Alright.

So driving home from work my alternator completely died. I had my roommate come jump me TWICE to get my car back home just as it died. I didn't wanna change it so i checked all terminals (fine) then went and got a new battery (which i did need already) and a new alternator. Swapped them and now im noticing the following:

When ignition is on but engine is off, SAFCII reads volts at a consistant 12.4-12.6 with nothing on but dome lights, SAFCII and Radar detector.

When engine is on, I get a consistant 13.7 - 13.8 volts with the same eletrical equipment on.

Do these figures look standard? is 13.7-.8 reasonable or shall i investigate further. I hear people getting 14.2-14.6 in some cases.

Also to note, i have a 255 walbro powered in the background which im guessing sucks up a lot of juice too?.. as it whines..ALOT

The alternator wires running to it seemed a little stiff but the terminals looked fine, as did the plug.
My belts also squeel for a good 5 minutes upon startup.

Defiant · 07-03-2008, 01:03 AM

Quote:

Originally Posted by mccurdy

When engine is on, I get a consistant 13.7 - 13.8 volts

Your rebuilt isn't putting out full power. Typical. Make sure it's over 14V at 2500 RPM.

Quote:

My belts also squeel for a good 5 minutes upon startup.

Suspect the harmonic balancer.
I changed my harmonic dampener just in time *Pics & Video*