Intermittent Battery light
 

Type of vehicle:
2003 Honda Civic Ex coupe Vtec Automatic
So i'm not much of a mechanic and I need your help! :facepalm: My novice head cant wrap around what the problem is. Here's the situation...I bought the car off a friend at work for $300 because it wasn't running and he just wanted to get rid of it... (now i could already hear the, "well that's why he sold it...") anyway he said right before it died battery light came on. it sat for 2 weeks in his driveway unable to turn on. Fast forward to me purchasing it and towing it to my dads house. I take off the battery and get it tested at autozone... battery is dead and no good so I buy a new one... I put the new battery in the car and it starts right up. I have one of those dewalt battery jumpers that has an alternator tester on it so I hook it up and I get an alternator error. I take off the alternator and get it replaced at autozone with a Duralast reman with warranty (more on that in a minute). So i get the new alternator installed and vuala! car turns on! I hook up the batter/alternator tester again and now it says alternator good. So I think its fixed all is good... not so fast, 2nd day after I installed the alternator battery light comes on and off on my dash... didn't think much of it because it didn't come on again that day. Day after, i'm driving to work and the light is coming on more consistently... comes off but then comes back on and off again. I was afraid I was gonna stall on the road because of what my friend had told me happened to him. I stop at Autozone to test out the battery and alternator with their tester and both pass. I get to work fine but on my way back home later that night i'm checking for a battery light and nothing comes up so I'm thinking, "ok maybe it fixed itself". Today i'm driving to work and battery light shows up again, again more consistently. I've looked on forums to no avail... only things i could think off are the following...
1. aftermarket parts especially reman duralast are sh*t for what i hear
2. alternator needs to be bolted in at 33 ft. lbs. (from what i read) I didn't have a torque wrench so wasn't able to measure the tightness of the bolts. I ordered one and will be checking it soon.
3. the wire that goes from the alternator (o ring that bolts onto the alternator) was tightened but not overtightened as I've heard it could damage it.
4. no fuses are blown... checked all fuses under hood and under steering wheel are good.
5. the alternator belt was not changed cause it looked in good condition but probably should replace it anyway.
6. probably unrelated but I thought i'd mention it anyway is that I try connecting my OBD2 scanner to the port but I get no power to my scanner. I checked pin 16 with a voltmeter and I do get power but my scanner works on my wife's car. At a loss here
7. There is a CEL that was erased when I replaced the battery so just waiting on it to reappear. Friend I bought it from says he had a CEL that had something to do with fuel mixture too rich.
8. I did notice today that the battery light came on as the car was changing gears not sure if that's consistent though. (I have an automatic)

PLEASE HELP! trying to avoid paying a mechanic to tell me what Ive already read.

*UPDATE* today friend told me he replaced the coils with cheap amazon ones... :_doh: something to worry about there. does this have anything to do with anything?

so just checked with multimeter...
voltage with car off 12.82 v
car on - 13.9 to 14.03

**UPDATE 2** I got myself a voltage reader while I’m driving and when the battery light comes on the voltage drops to below 12.5... I’m talking about right about 12.3. Bad alternator or bad ELD (battery current sensor)???

Re: Intermittent Battery light
 

Ecu is probably fried

Re: Intermittent Battery light
 

check your alternator mounting bolts are done up tight enough...torqued to proper specs,

these alternators are grounded by the bolts, if they are loose, it wont ground and cause all kinds of issues

Re: Intermittent Battery light
 

any way to check ECU without having to buy another?

Re: Intermittent Battery light
 

yes this will be my next check, i will be tightening bolts up to spec and see if the issue is fixed. Will update once its done

Re: Intermittent Battery light
 

While the engine is running and the battery light is on consistently, go out and unplug the 4 wire plug from the alternator.
If the battery shaped warning light now stays OFF then the alternator was causing it to stay on. Bad alternator.

But if the battery light stays on even though that 4 wire plug is disconnected, it's not the alternators fault.

Aftermarket alternators are sometimes just crap.
A poorly grounded alternator can ruin the PCM (that's why it's so important to get the mounting bolts tight)

Does your code reader not power up at all?
Or does it power up--- but can't communicate with the PCM?
OBD connector terminal 16 is b+ power, terminals 4 and 5 are the grounds. If your code reader won't power up, these are the 3 that need investigated.

Re: Intermittent Battery light
 

is there any way to check this if the battery light doesnt consistently stay on?
The OBD2 scanner i have is one that requires an app on your phone. It gets its power from the vehicle. It had been working fine on my wifes car before but just doesnt power up when i plug it in. I did verify pin 16 has power with my voltmeter and will be checking the grounds tonight.

Buddy i got it from did tell me he bought some cheap coils off amazon for it as well... thinking about replacing them with quality ones like NGK but would that cause any of those issues? should I check the starter connections?

Re: Intermittent Battery light
 

I'm sure I could come up with a way, if I had to.
The immediate goal was to figure out if the new alternator is causing the idiot light to turn on when it shouldn't be on.

If the idiot light was not on at the wrong times when the original alternator was installed, I'd strongly suspect the new one is causing the new problem. That's a reasonable assumption, yes?

BUT I have to test and prove, because suspicions and assumptions are not proof beyond a doubt, and warranty departments don't always like to pay claims for replacing parts that work when tested.

When you try to return it--- autozone may just throw it on a tester and try to tell you "it's charging ok so it's good."
IDK what actually happens there, but you might need to be able to tell them exactly why you think you know so much more than what they and/or their bench tester machine says about it. They might not be able to check whether or not the regulator isn't able to control the warning light correctly,

Seems like every autozone has at least one old grizzled graybeard who just rolls his eyes and mumbles 'here we go again' as he chucks your alternator over his shoulder into a tote full of starters and alternators behind him, then shuffles of to get another 12308
lol

AND if 4 more bad alternators still don't fix the light, how are you gonna know what's really going on?

Did it EVER work in this Civic? That's handy info.
If you check and DO find power/2grounds are truly present in the obd plug, you might wanna check if the terminals are worn and lost tension
If one of the grounds is missing (no continuity, no current flow) it could be a factor in other issues as multiple items and systems often share circuit ground points.

I know this shouldn't apply to you (yet) because yours doesn't power up in the first place, but I may as well say that sometimes the electronics on the market just don't play nice with a cars computers. Even at the professional level there's plenty of glitches.
What problem are you trying to solve right now?

Re: Intermittent Battery light
 

Right now the most important problem is the battery light... i dont wanna be left stalled somewhere even though i DO carry my jumper with me. Gonna tighten the alternator to spec then update on the outcome. thank you so much for yalls responses so far!

Re: Intermittent Battery light
 

I recently had this same problem except my reman alternator was from O'reilly's and it lasted 3 months before behaving like yours. In your video, it appears the light only comes on at the lower RPMs. That's exactly what was happening with mine...battery light would flicker.

I ended up replacing the O'reilly's reman alternator with a new Remy from RockAuto. It's been about a month and all seems good with no battery light.

I took the reman alternator back to O'reilly's and it tested good on their in-house tester. But I don't trust that thing. The voltage output with that alternator was jumping around all over the place when I measured. It would jump around between 12.5V and 14.3V. I assumed bad regulator. So I believe their test is crap.

I also cleaned up all my grounds and replaced the front ground strap. So if I were you, I'd replace the alternator again with either new or a used OEM. Problem should go away.

Re: Intermittent Battery light
 

As others have said you possibly missed a bolt on the alternator which is causing a grounding issue. This is the most common thing we see when a scanner will not talk to the ECU. Check the bolts; there's one on top of the alternator, another going from the mounting bracket underneath to the alternator, and a third bolt from that same bracket to the block. I believe most people miss the bracket to alternator bolt because the wingnut utilizes the bolt as well and makes it appear to be tight.

Re: Intermittent Battery light
 

This is good info. So I would say that before you try replacing the alternator as I suggested above, try cleaning the contact points for alternator case ground.

In my case, all my bolts were tight and the contact points were fairly clean after I installed the reman alternator from O'reilly's. That's why I immediately assumed the regulator was bad and replaced the alternator again.

I cleaned all the contact points with a brass bristle brush and then sprayed them with CRC Electrical cleaner. That stuff really makes a difference on corroded contacts even when they don't look that bad.

Re: Intermittent Battery light
 

hey thanks for the response... today i noticed that light comes on when i hit the gas... once I let go of the gas battery light goes away then comes back on when the RPM hits 1000. Also another thing is that its been 3 days that battery light comes on within a block from leaving my apt but doesn't come on at all at night. this one is stumping me. Ive heard that reman alternators are sh*t but they wont take it back unless their machines tests come back as failed... and they just wont accept a return if i wanted my money back... $150 down the drain? Guy at autozone said it may be something to do with resistance because its only happening during the day when its hot. idk what to think of it anymore

Re: Intermittent Battery light
 

At night, most people drive around with the headlights on. That's more amp load on the alternator, and yes that can affect the idiot light control inside the junk alternator.

sounds like you now know several conditions that cause the idiot light to come on when it shouldn't be on.
So when its to a point you KNOW the light is gonna be on, just unplug the 4 wire connector and drive it around long enough to confirm something. (you can't do this for long because the alternator can't generate electricity while it's unplugged, and you will eventually run the battery down without the alternator working)
Does the idiot light stay off? Bad alternator.
I covered this in a previous reply. You have to be armed with accurate diagnostic info.

Re: Intermittent Battery light
 

thanks, yea ive seen your responses to several people... ill unplug the alternator during the day and drive around my apartment complex and see if that fixes that happens. Thanks again

Re: Intermittent Battery light
 

hey how’s it going so today I went a replaced all the electrical tape on the alternator wire, checking it as I went, no damage. BUT!!! I unplugged the blue connector from the alternator and drove it around my apartment and the light did not come on. I made sure I had the lights off and recreate the conditions I was in when the lights came on in the first place and nothing... I’m thinking defective alternator

Re: Intermittent Battery light
 

Yeah probably. You may be able to at least swap that reman alternator for another one. You must be adamant that the first one they gave you does not work in your car. Tell them the steps you took to diagnose it. Maybe you can exchange for a new alternator??

But worst case scenario, you will have to buy a new one and lose the money for the first. That's what happened to me, but at least O'reillys exchanged the bad one for another reman. I'm keeping that one as a spare.

I currently have a new Remy installed, and it's been good for about 6 weeks. We'll see how it holds up over the next year.

Re: Intermittent Battery light
 

Sounds like you've pretty much confirmed it.

Re: Intermittent Battery light
 

I'm having almost identical symptoms but mine are in an 02 LX D17A1.
I first replaced the battery, it genuinely was bad. Then when the car shut off on me one day after turning on the a/c and radio and gauges completely stopped functioning and car wouldn't restart, I had the alternator tested...came out bad. Bought a reman unit because I couldn't find nor afford a brand new one.
Car seemed fine for about a week of daily use. Then my son and I went to the grocery store one afternoon and I noticed the gauges had stopped functioning again at a red light. When I tried to go through the intersection, the car bogged and stalled and we had to push the car to get it started.
Took the recently replaced alternator to be tested...bad again! Parts store replaced it and I installed it. Same series of events. After going back to have the 4th one replaced, they refunded my money. I found a reman factory unit with a lifetime warranty. I bought it. It worked great for about 2 months. Then randomly the gauges would stop. Then once I had drained the battery of course the car wouldn't start. I've sent 3 defective alternators back so far.
The one on the car now is starting to act up like the others did.
When it's running, it actually runs great. But since I replaced that original alternator, it's never been right again.

Re: Intermittent Battery light
 

Go get an OEM one from the junkyard if you're not going to buy a new OEM, you're just going to keep having them fail

Re: Intermittent Battery light
 

Sounds like what you'd see when the PCM is frying.....Alternator mounting bolts are not tight enough?