2004 Civic Battery light on
 

I have a 2004 civic that has a battery light stuck on now. It starts no problem. But if I leave it idle, it will run and die at random. I've taken the alternator 4 pin out while it was running light stays on. If I drive it and give it power the car will shut off then restart. Sometimes the battery light will shut off and it will change to a check engine. I was driving it on the highway when it first happened and the "Drive" green light shutoff and so did my temp gauge. I'd throw it back in neutral while driving and restart it. When the drive green light shut off and temp gauge shutoff I have no power. Charged battery and still the same issue. If I rev the car in park, at high rpm the engine will bounce back and forth. At first I thought it was my oil since I have an oil leak and oil will lock out vtech, but I fixed the oil and same issue.

Re: 2004 Civic Battery light on
 

Can anyone give me some type of idea? It's the weirdest thing because the car starts no problem. At low idle it dies pretty easy but will start right now. I still have power but it will randomly shut off to the point that it jerks you back and then restarts. Could it be ELD? MICU? PCM? Is it just a stupid ground? My grounds are shit for sure but wouldn't that affect the car starting? I need some idea because I have a 7 hour drive I need to do and don't want to pay for a rental. The battery fuse looks fine too although I broke the cap off the top awhile ago and put a piece of ducttape on top. I literally have no idea as to why the battery light is on and the car dies at random. I even put all my accessories on like rear defrost, radio, heat, high beams, etc. Looked like there was no change in rpm or anything although I guess I should have a volt meter.

Re: 2004 Civic Battery light on
 

Loose bolts on the alternator bracket are common. The bracket is the ground for the alternator. If left like this it will ruin the PCM.


What is the code for the CEL?

Re: 2004 Civic Battery light on
 

I'll check the bolts, I don't get to pull the CEL Because the light shuts off. It ends up coming on for a bit and then switches over to battery light.

Re: 2004 Civic Battery light on
 

OK new info I think I did the alternator 4 plug pull thing wrong. So I turn the ignition to on. The Battery, CEL, and Oil light stay on. The park light on the dash is on. But my drive light is flashing.

I left the car alone for awhile to see what it would do and then the battery light went off. I started the car and the rpm wasn't working. I turned it off and then put it back to on and it was the same as before (The 3 lights, Park, with Drive flashing).

So this time I unplug the 4 prong. The Battery light and oil light stayed on. CEL went off, and the green drive light was not intermediately flashing.

I plug the alternator plug back in and the battery light goes off.

Is it the bottom bolt to the alternator that is the ground? Anyone have a 2004 EX Alternator diagram?

Re: 2004 Civic Battery light on
 

So I forgot to mention after I unplugged and replugged in the alternator with the battery life off, I heard clicking near the TCC but I don't have a manual so that solenoid is a shift lock solenoid maybe? Would it cause the flashing D and or battery light?

Re: 2004 Civic Battery light on
 

I had a guy at napa test the alternator and battery when running. He said the battery was fine and that the alternator was a little low. The alternator I believe tested at like 13.3 and he said you wanted it above 14. He used a cheap computer to see if there were any CEL codes but none. He did say there were codes he didn't see with his cheap computer and that I would need someone with a better computer that could simulate the car running while off to see them. I do have a maintenance light on.

What I don't get is like what it could be? When I'm driving and the car shuts off or goes to die it just jerks you back and mostly restarts. I've never had it fully shut off when I was driving other than on the highway when it first happened and I still was moving but had like no power to move. I'm gonna tear everything down again and check to see what the issue could be.

Any ideas? Thanks.

Re: 2004 Civic Battery light on
 

I tightened alternator belt and tightened down the bolts. Car just kept wanting to die when I tried to drive it distance today. The battery light went off, CEL came on, the Speedo and the thermostat gauge died. I stopped at napa.with CEL on and car just running like shit and noticed a burning smell in the cabin. He said he could only pull the code if the car is off. So we shut off the car, the CEL went away and back to a battery. He ran it anyways and no codes.

So is it not giving me codes because the PCM? The burning smell is coming from the engine bay fuse box. If I pull a fuse and smell where the fuse goes it smells burnt. Throughout the whole board not specifically to a certain fuse.

Re: 2004 Civic Battery light on
 

So the alternator bolts were loose?
Probably fried the pcm

Re: 2004 Civic Battery light on
 

Nah the alternator was tight. Everything seemed to be legit with it, I just tightened the spindle thing and adjusted the tension. If anything I think I may over over tightened the bolts/belt. The belt feels very tight now.

If it's the ELD, say I smell that the ELD burnt out or something. Would it affect the PCM? The ECU has a fuse specifically to it, wouldn't that fuse go before the ECU does?

My battery fuse looks cracked a little on the side with the middle piece still intact.

Is there an ECU test? I wonder if the reason why the codes aren't showing is because the ECU is fried. I just had it inspected before all this started through OBD2 and no codes.

Re: 2004 Civic Battery light on
 

Re: 2004 Civic Battery light on
 

Agree. If the top bolt is properly tightened, you won't be able to move the alternator to tighten the belt without a whole bunch of effort. OP beware, no codes is not the same as no communication. No communication is bad, very bad.

Re: 2004 Civic Battery light on
 

Bolt mounting bolts we're tightened down tight but the tensioner wasn't. But the tension IMO was at a good tension. I have no movement in the alternator but it's possible it wasn't grounded.

The NAPA guy can get maintenance codes but when whatever dies when I'm driving it turns off Batttery light and goes to CEL. Can't pull the CEL because when you turn the car off and restart the CEL is gone.

Lets say it was ECU and I can't communicate, Wouldn't I still show CEL if there were CEL issues? Wouldn't it show up in my inspection? Although the battery light showed up after.

Re: 2004 Civic Battery light on
 

Yeah I know, When the car goes from battery light to CEL I go into limp mode. Star the car up and it kinda runs crappy but I get powerband back and communication, but it's risky that it will shutoff and change over to CEL.

Re: 2004 Civic Battery light on
 

Tighten the alternator bolts correctly before you completely ruin the PCM.

Re: 2004 Civic Battery light on
 

To be really clear you mean losing it to spec because a lot of the issues happened after I tightened it a little. There should be a little slack? Also do you think I fried the ELD at this point from what I smelled in the cabin and when I start it runs like crap?

Re: 2004 Civic Battery light on
 

Here's your torque specs:
https://cimg1.ibsrv.net/gimg/www.civ...85fdd3c1d2.gif

The mounting base for the alt (attached to the block) needs to be clean and tight too.

How about ground cables to the engine and trans?

The PCM gets fried when the alternator loses it's grounding. If the engine and trans lose their ground cables, that's the same effect as the alternator losing its ground from someone leaving the bolts loose.

Re: 2004 Civic Battery light on
 

My ground from my chasis to the block looks bad. I try to clean it but still looks bad. I'll work on changing the grounds this week, changing the ELD, and putting in a new alternator.

I did hear clicking noise underneath the glove box when the car would cut out every other minute or so.

Re: 2004 Civic Battery light on
 

Why? Is it bad?





Stop driving the damn car until you get the root of the problem fixed. Right now the PCM may still be saveable, but if you continue driving it this way it WILL ruin the PCM

Re: 2004 Civic Battery light on
 

Can the alternator ground out inside the coils? I drove it today and weirdly it was acting normal again aside from 1-2 small intermediate shutoffs for seconds.

Ezone when the car goes to "die" I've noticed it's when the car is downshifting or I am breaking. It's like when you are in high (3500) rpm band and the car shifts down (auto) to change to the next gear. It doesn't always happen but when it does there's a click under passenger side near glove box and then right back on.

Re: 2004 Civic Battery light on
 

The PCM is freaking out from runaway voltage, and that can cause a myriad of symptoms including relays clicking, various warning lights on the dash, PCM operating in backup or limp mode, immobi light flashing, trans not shifting correctly, gauges stop working or become erratic, loss of scanner communication, and more.



Lack of ground for the alternator is not a fault of the alternator at all, and all this will still happen with a perfectly good alternator if it's not properly grounded.


What part of "stop driving the damn car" wasn't perfectly clear? How much will a PCM cost when it finally becomes permanently ruined? (plus programming)

Re: 2004 Civic Battery light on
 

Too much, and I have no problem not driving it but I need to understand why it's doing what it's doing. By driving it I get it, more problems more money. But you explained to me why it's doing it (Runaway voltage) So I'm gonna go through it all and report back. Thanks

Re: 2004 Civic Battery light on
 

Re: 2004 Civic Battery light on
 

I've cleaned the terminals, did new grounds, changed the alternator because when I tightened down the bolts I stripped one in the old one, and changed the ELD which is what smelled burnt when the car went into limp mode driving.

The car starts, idles, dies and restarts (click under the passenger side). The car drives, there's power, vtech engages, etc.

The battery light is still on, The car randomly stalls out. Sometimes it's when I push the breaks, sometimes it's just random. I've wiggled the key to see if it was the ignition.

Anymore ideas? I don't have money to get it diagnosed. I'm gonna try and see if I can run the MCU troubleshoot. I read in another post that someone changed the ELD and MCU and it went away.

I really don't think it's the PCM because the car isn't in limp mode. It only goes into limp mode if I'm driving and it hard stalls and restarts. Then I restart it and the car is out of limp mode.

Re: 2004 Civic Battery light on
 

DTC Code 2 and DTC Code 5. The dome light flashed twice and then five times.

Attachment 113307

The troubleshoot says that if 2 and 5 are simultaneous that there is an "open in communication wire" Open YEL wire in the under fuse dash/relay box E10/E24.

So what exactly does that mean? Is it related to the Battery light/car intermediately dying?

Should I change the MCU Like the other person that said it fixed the problem? Why is the MCU randomly shutting off the car/restarting it?

Re: 2004 Civic Battery light on
 

Consider this: If the PCM lost its ability to communicate with the micu, would the micu set that code?
I'm not sure the micu has that ability.

Re: 2004 Civic Battery light on
 

The only thing is the car drives normal aside from the battery light and the intermediate shutting off for a split second. When it shuts off it's a hard shutoff and the main relay clicks like it's priming the fuel pump.

I suppose there really is no way to test the MCU and the ECM? Can I do anything with the yellow wire at E10/E25 to test it?

I think my approach now will be what I saw on this website about changing everything out one by one starting with the dash, MCU, ECM. The question is would the gauge assembly cause this type of issue? DTC 5?

Does the ECM go through the gauge assembly first and then into the MCU? I don't understand what it's recommending with that yellow wire.

Re: 2004 Civic Battery light on
 

Simple continuity test, making sure that wire in question is a complete circuit between the two connectors mentioned, and a terminal tension test.





I'll also suggest you search this forum using the term "loose alternator bolts", and you can read about countless ruined PCMs

Re: 2004 Civic Battery light on
 

If I get a PCM that comes with key and tumbler/ignition and pcm do I have to have it programmed?

Also which PCM's can I use with a 2004 civic ex auto?

Thanks

Re: 2004 Civic Battery light on
 

Sorry this is late, I forgot about itThey would be a matched (married) set, as long as you install all of the items together it should run. Except you'll now have a different key for the ignition that won't fit the doors
04 and 05, must have same engine (VTEC) and same transmission