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Hello all

I am new to the forum but have ready alot of posts on this topic. My battery indicator light has turned on and will not turn off.

Background on my car:
Newer battery - One year old
New Alternator
Checked all three fuses and all are good.
Confirmed continuity on all wires coming off of the alternator to the ECM
Pulled 4P plug on alternator and light did not turn off.
Read voltage of wire with IG On and engine off
B/Y - Battery Voltage
W/B - 0 volts
W/R - 5 Volts
W/G - .04 Volts

With engine running
B/Y - Battery Voltage
W/B - .7 Volts - I believe this is bad and should measure battery voltate - What do I learn from this?
W/R - 5 Volts
W/G - 0 Volts

Just trying to see where I should go next?

Any help would be greatly appreciated. I have read that this may indicate an issue with my ECM but did not want to go through this without more work.

I have not checked the ELD yet?

Thanks again.
Ken

 
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Aftermarket or OEM alternator?
If aftermarket return it and go get an OEM one, either used from the junkyard or new from honda

 
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Battery light was on with oem alternator. Replaced with aftermarket and light is still on. Does the alternator output or input on the white/blue wire?

Thanks

 
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Hello Group

One more update

I did a check that I read about on the forums where you pull the 4 wire plug on the alternator and then turn the IG On but not have the engine running.
the battery light if working properly should not be lit per the forum. In my case the light stayed lit. This would typically mean a short or ground. I ready the Whilte/Bue wire to ground and did not have any ground ready with my meter. I also tried to wiggle wires to find a short and did not find any issues.

I have not found a way to make the light turn off. Does this mean the ECM is causing the light to be lit since it is the ovly thing between the light and the wire?
Maybe the cluster?
Thanks for any help.
Ken

 
Rep Power: 223

The last post in the below thread has a link to the service manual. Page 4-28 is the beginning of the charging system troubleshooting. Let us know where that takes you.

https://www.civicforums.com/forums/1...pdated-10.html

 
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So I used the manual and am stuck.

I went through the multiplex troubleshooting and had no DTC found. Then went through balance of process where you check mode 2 and it seemed to fail but the manual states could be gauges, multiplex or ECM. That is not much help because I already knew that.

I did the gauge check and it seemed to go fine. All light came on and off and the gaugues did they span.

Is there any way to rule out the ECM vs the multplex.?

It makes sense to me that it one of those two items because when you unplug the 4p connecto on the alternator the light does not go out and the white/ blue wire reads continuity and no ground.

Any more help out there.

I want to get rid of this battery light.

Thanks

 
Rep Power: 223

What do you read for battery voltage with the engine running? Go for a short drive or let it idle for a while to recharge the battery a bit before checking.

The charging system indicator light could be correctly telling you there's a problem. Page 4-29 has steps for testing the alternator.

 
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Hello BrotatoChip

I have read this several times and read 14.3 to 14.9 volts ever time I read this. I do find this interesting because I never read the lower voltage of 12.4 to 12.9 volts.

Civic appears to be charging well and no issues starting car yet.

Thanks
Ken

 
Rep Power: 223

You should see around 12V when the engine is not running.



Sounds like it is charging ok. At this point it may be difficult to narrow down. You said you ran a diagnostic on the cluster which makes me think it's an issue with the ECM. I don't want to completely rule out multiplexer or aftermarket alternator though.

Do you have a OBD2 scanner with the capability of displaying live results? One thing you might be able to do is use a scanner to read battery voltage from the ECM while the engine is running. I'm thinking the ECM reads battery voltage then sends it to the cluster over a communication line. If the ECM is incorrectly reading battery voltage then the cluster would turn the warning light on. You can get a ~$20 scanner on Amazon that connects to your smartphone via Bluetooth/WiFi. Then using a free app you can read this data.

 
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Well my saga continues:

I have been trying to do all of the easy checks first before I pull the ECM.

I changed the ELD today and verified the three wires going to the ELD

The black wire was good to ground
The Green/Red wire going to E10 of ECM had continuity and not to ground
The wire going to IGN - forgot color had continuity to the internal fuse panel. When I pulled the 10amp fuse it showed no ground. Prior to pulling fuse it did have a low resistance to ground. i will assume this is do to being connected in the IGN circuit,.

The battery light is still on.

Any more ideas?
Thanks for any help. I have to admit I hate lights on my dash and this is annoying me bad.

 
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Brotatochip

Question on one item that you made from a previous post.

If I pulled the wire connector on the alternator and the battery light did not go out then how can the aftermarket alternator cause that. I also tried to ground the white blue wire at the 4 wire plug and the light still did not go out. Does this man the ECM or mutiplexer still has to be the issue?

Thanks just trying to work my way through this problem.

 
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No worries. I appreciate all help. I know that I don't know it all and just trying to make sure I am not missing something.

Thanks again.

 
Rep Power: 223

If the ELD were not working you would see an engine fault.

Unless you know something I don't I don't see how disconnecting the alternator would make the battery light go off. The engine is looking for 13.9 - 15.1 V while running, if outside that range the battery light is turned on. With the alternator disconnected I imagine it would not be charging at all causing the light to be on constantly.

With all the information you've provided and all the testing you've done I'm leaning towards a bad ECM. Unfortunately there is no easy way to prove this. If you know someone with the same model as your Civic you could swap the ECM, bypass the immobilizer to get the car to start, then see if the battery light is on. This may be what you have to do with a junkyard ECM anyways.

As I mentioned, before if you have an OBD2 scanner that allows you to look at live data you can read the battery voltage from the ECM while the engine is running. If the scanner shows the ECM is reading the battery voltage incorrectly that may be a sign.