Battery Light Is On
 

Basically, in my 2002 Civic EX 2Dr coupe my battery light is on. My brother in law is a mechanic and he and I spent all day trying to investigate all the obvious things. I just replaced the battery and today we replaced the alternator hoping that would solve the problem. Obviously that didn't do the trick. We used and OEM alternator to replace it. We didn't have access to a code scan tool but we checked all the fuses and like I said all the obvious things with no success. Anyone have any ideas where to look in the meantime?

RE: Battery Light Is On
 

I have always read and heard that if the battery light is on, it means one of two things,
A. the Alternator is not charging
B. the Battery may be defective.

I see you have already investigated the obvious so your on the right track.

Have you used a tester to verify that the alternator wiring is not defective in some way, running from the alternator to your battery, or maybe a loose or bad ground?

Have you contacted a dealer over the phone with similar questions?

These are the only 2 questions that come to mind, I haven't had alot of electrical issues over the past few years, but I know loose wires often cause a painstaking problem. You might try a tester and check the wiring to and from the alternator, and perhaps monitor the battery over the course of a day or so, see if the sitting voltage drops alot for no reason, you might have something grounding or a faulty switch somewhere causing the light to be on.

RE: Battery Light Is On
 

i would start checking the wires. maybe something is grounding out that shouldnt be or something

RE: Battery Light Is On
 

Start the engine and then look at the battery voltage. The alternator onthe 2001-2004 Civic will take the battery voltage up to 14.5 Volts when it is working properly. A battery voltage of 12.7 or less will mean the alternator output is not up to snuff. On the 2001-2004 Civic there is an 80Amp fuse between the alternator output and the battery + terminal, assume this has been checked. Also, on the 2001-2004, there is a 10Amp fuse under the dash for an alternatorIGN input.

RE: Battery Light Is On
 

There are 5 wires to the alternator plus chassis ground, they are:
1. Terminal B, BLK to Fuse 19, 80Amps and then to the Battery +
2. Terminal C, WHT/GRN to ALTERNATOR CNTRL SIGNALin the ECM/PCM
3. Terminal FR, WHT/RED to ALTERNATOR FR SIGNALin the ECM/PCM
4. Terminal L, WHT/BLU to ALTERNATOR L SIGNAL in the ECM/PCM.
5. Terminal IG, BLK/YEL to Fuse 4, 10Amps HOT (+12V)in IGN ON or IGN START.

RE: Battery Light Is On
 

I have checked the battery voltage and it maintains a steady 14.5-14.8volts even when all other systems are running. I looked at the harness and checked all the fuses as well. I can't see anything that is obvious put I haven't done any point to point wire checks to see if there is a break in the wiring. It just seems very odd to me that the system is still charging like normal but that light continues to stay on. Has anyone ever had something in the dash itself go bad causing the light to malfunction?

RE: Battery Light Is On
 

I tried all of the obvious things that everyone has stated and thanks for the help by the way. I just can't figure out why when the system appears to be charging at normal (14.5-14.8) when all the systems are running and the battery light remains on. I have a chilton's manual and have tried to trace through the wiring to see if there is anything there but everything seems functional. Does anyone know of any glitches that the ECM may cause?

RE: Battery Light Is On
 

Have you tried forcing a "Maintenance RequiredIndicator" Reset procedure: To do this,TURN the IGNITION OFF, push and hold the Odometer TripReset Buttonand HOLD IN.Turn on the IGNITION, wait 10 seconds and then release the Reset Button. The procedure is in the manual if I did not do a good job of describing. Just a hunch, because the "Charging System Indicator" is controlled by the same Guage CPU as the "Maintenance Required Indicator" and the signal from the ECMto this Guage CPU comes in the form of a communications link (SEFMJ) which carries a lot of other information that we know is working.

RE: Battery Light Is On
 

I tried that and it let the battery light turn off but as soon as I started the engine the light came back on. I am beginning to wonder if I don't have a module or ELD going bad. I am guessing it's not the ELD because the alternator is charging but who knows. Is there any way to diagnose the ELD elctrically to see if it's intermittent or something.

RE: Battery Light Is On
 

If all else fails, and the car works correctly every time you start and drive it, a small strip of electrical tape over that light works wonders :-)

I used to drive a car that had like 5 lights on all the time, dealers said it was normal ?? Ok mr. dealer guy.

RE: Battery Light Is On
 

I am waiting to get a code reader and see if that can tell me anything. I am just worried about have to get the thing towed again. Not that big of a deal I know but just don't want to have the hassle. I am hoping to locate a wiring diagram and go through and check all the system grounds and make sure nothing is loose and then go from there. I'll try and keep everyone posted

RE: Battery Light Is On
 

Does anyone know if I should be able to read directly across the ELD.
By that I mean when I do a continuity check with the Fluk meter I have I can read directly from the 80A battery fuse to the 40A fuse on the other side of the ELD. From what I have gathered so far the ELD is not a fuse buta current transformer and typically I don't think you should be able to read directly across it. Any knowledge from anyone on whether or not my thinking is correct.

RE: Battery Light Is On
 

So it looks like your Gauge CPU and Driver Circuits are all OK! Is there anything else electrical not working properly on your vehicle,maybe something not related could be causing electrical noise which upsets CPUs and disturbs communications etc. For example, do you have Daytime Running Lights? If so,do they seem to be working properly? etc etc

RE: Battery Light Is On
 

Everything else seems to function like normal. My bro-in-law and I took the car out on the highway and everything ran fine except the temperature gauge. Once we got back to the house he looked at the sensor unplugged it and plugged it back in and it worked like normal. I am just thinking do I have an ELD shorting/malfunctioning or an ECU going bad. The original problem started with the transmission feeling like it was gone. I was on the highway andthe carbasically just shut down. Took it to a transmission guy he found nothing but a battery going dead. So he repalced the battery. Tried to do a code scan at the time and he wasn't able to get anything.Since then it has been fine until the light came on the other night and it did the same thing. So we changed the alternator but that as you know didn't change the light status. I just cant figure it out.

RE: Battery Light Is On
 

I would bet on the ELD problemrather then the ECU because the ECU is the controller running a closed loop. The ECU would know that the loop is malfunctioning because of no signal from the ELD in response to a change in the output to the Altenator. As a result the ECU would probably default to max Alternator output and flag the problem.Also, the ELD unit may be repairable, its function is to amplify the voltage drop across the strip of metal where the alternator current flows. The ELD most likely has a OP AMP and a few components. Also, do not overlook a bad 3 wire connectorat the ELD Unit.

RE: Battery Light Is On
 

I have been considering jus going to the parts store or Honda dealer and use my brother's employee discount pick up a new one and replace it. I'll let you know what the status is when it is all said and done.

RE: Battery Light Is On
 

Do not open the package it comes in until you have exhausted the other possibilities that may arise in the disassembly process. You may end up wanting to return it unused/unopened after youknow the cost of the beast.

RE: Battery Light Is On
 

Already spoke to the dealer and the cost of the ELD is $26.00 bucks so it's not that big of deal to buy and put it in. I will remove the first one and check the harness and make sure there is no damage there.

RE: Battery Light Is On
 

I have replaced the ELD and I still have the battery light on. I am able to reset the light but as soon as I turn the car on there goes the light. I am going to try and locate a complete honda wiring diagram and trace through the whole circuit so if anyone has a location on one please let me know. I am about at my last option which would be take to the dealer and most likely get taken to the cleaners.

RE: Battery Light Is On
 

Any have any ideas other than what I have already tried?

RE: Battery Light Is On
 

I ran a code scan that my brother-in-law has and it gave me no DTC's or error codes found. Could this be a bad ECM or even dash?

Any help would be greatly appreciated.

RE: Battery Light Is On
 

Maybe the test wire that goes to the charge dead light is faulty. This is the FIRST thing that you check, according to the Honda book. Get your Honda book out, and it has a flowchart to help you troubleshoot (including what wires to pull where).

RE: Battery Light Is On
 

Was this problem ever resolved?

Was this ever fixed I have the same issue

Fixed
 

pulled the 7.5 amp fuse bottom right under the dash and left it out. Light is off. (Fuse #10)