04 blue civic

Hello all. I have a 04 civic ex that the battery light stays on constant. Alternator is charging tested both on and off car. Battery brand new and fuses good. Thought possible load balancer so purchased new and still light on. Anyone have any suggestions or seen this issue? Possible anyone have diagram for Ecu so I can trace wiriring from there to alternator?

mac25

Maybe check

-the tension on the belt
-battery terminals are tight
-all grounds are clean and connected (no major rust)

04 blue civic

Terminals and belts tight. Checked ground from head to upper radiator support. You know of any others?

mac25

The main block/transmission ground is under the air intake connecting the body to the transmission. The battery ground runs from the battery to the body in the same area.

Maybe make sure there is no water in the alternator terminal and that it is fully clicked in as well as the alternator ground.

Is it dying at all or is the light just on?

04 blue civic

Ok will ck that. No water connections are good. No running issues just light stays on.

ezone

With the engine running: Unplug the 4 wire connection from the alternator and check the warning light

If the battery warning on the dash is off, the alternator is bad.
If the battery warning stays on, something else (likely one of the other control units) is keeping it on.

04 blue civic

Tried that yesterday. Unplugged four wire connector light stayed on... any ideas?

You have a wiring diagram by chance?

ezone

PCM, gauge cluster, MICU, or wiring.

Anything else weird happening with electricals? Illuminated entry, AC, key and lights reminder beeper doesn't work?

04 blue civic

Checked grounds and cleaned still on...

Drove down to store noticed when headlights on lights dim while driving let off accelerator get brighter. However if just sitting in park and accelerate can't duplicate.....

Ac works. keyless entry works. I did notice that when start car the instrument cluster is lite up and doesn't change when cut lights on.. can't remember if did that before.. lol

Any suggestions?.

ezone

Adjust the brightness control with the headlights on, and adjust same control again with the headlights off.



This is probably normal ELD action. Depending on electrical loads, charging needs, and driving conditions, the PCM can run the alternator high or low as it sees fit to conserve fuel.
Would that be the ELD unit in the engine compartment fuse box?


Got any fault codes?

Step 3 in troubleshooting is to perform the gauge cluster self test and note if the charge light blinks along with the rest of the lights during the test.
If it doesn't blink, replace cluster.
If it does blink, go to next steps.

Then there's checking the fuse for the alt and making sure the (alternator 4 wire plug) blk/yel wire gets 12v with the key on...

Then checking individual wiring between the PCM and the alternator, etc. etc.

04 blue civic

Ok will try the self test.. will google how.

No dtcs

Will check power on the wire stated. Fuse is good

And yes the eld

ezone

Search this forum too, I know it's been posted a few times here.

04 blue civic

Did the guage test and battery light flashed as should. Took out of test mode and the light went away once started. Cut off and restarted came back on....

ezone

That's weird AF.

If it does this again or anything else weird, disconnect the battery and hold the cable ends together for a few minutes....as a sort of reboot for the microprocessors.


Oh, I missed the edit LOL.


Get the service manual and follow the troubleshooting guides for 'charging system indicator stays on'

04 blue civic

Do you mean the actual Honda one? Or one of the parts stores?

Do you know of a Honda one online to download?

ezone

Search this forum for "looking for a 7th gen manual for free",
start on the last page of that thread for newest links

Many of the links lead to international versions instead of strictly US/Canada version....so you have to check the car/body/engine versions carefully

CraigW

iTrader: (1)

Here is schematic..

PM with email and I will send you the rest.

04 blue civic

Ok so didn't have a he's scanner so I disconnected battery to ck continuity in the white blue and white green wires. Have none.

Any suggestions on where to ck this? This issued happened after shop replaced timing belt

ezone

White/blue from alternator goes to terminal B10 of the PCM
White/green from alternator goes to terminal B18 of the PCM....


you are positive these two are open circuits?


During a timing belt service I lift the alternator and set it on top of the engine, so IF this happened during the service I'd suspect the wires broke near where the harness would have been tugged on, likely at the branch that sticks out near the #1 ignition coil

but really if they removed the valve cover all the way (I do not normally remove it, I only lift it up a little bit) wire breaks could be anywhere in the harnesses up top.


Make the shop fix their mistake?

04 blue civic

They refused said they did nothing wrong. Therefore I'm sol. Lol

At first I found one alternator bolt was loose and stripped. I purchased new bracket and all the bolts. fixed that found light was still on. Alternator again charging.

So I guess now just chasing the continuity in the wires from a to b. I wasn't sure if any other wire in the t belt area lead or was one of those by some chance.

Yes neither wire had continuity

ezone

Of course they would never admit fault, and wouldn't even consider checking into it to see what happened.
Blow you right out the door, they got your money for the timing belt job already.

That says a lot.

04 blue civic

Right... so now I'm stuck with fixing their mistake....


i guess I could check continuity between alt. connector and under dash fuse box. Not sure if same wires or not.. will look into searching for a diagram for that.

CraigW

iTrader: (1)

Did you test & inspect close the 10A fuse that is shown ??

Did you get the email with rest of info sent ??

ezone

This would be confirmed by simply checking

"and making sure the (alternator 4 wire plug) blk/yel wire gets 12v with the key on..."

04 blue civic

No continuity between wires to ecm

The black red wire measured 0 volts when test says below 1 volt move to step to test above wire to Ecm

Black yellow had battery voltage.

Fuse is good

04 blue civic

So I believe is a break in wires white blue and white green to pcm since I have no continuity. Now to just find the break. I thought ab just running two new wires outside of car to connector to see if light goes off as a quick test. Any ideas?

04 blue civic

Yes I did thanks my friend

ezone

On the alternator, Pull the rubber boot back and inspect where the 4 wires attach to the terminals inside the connector shell, for breakage

Untape the wires from the alt to the valve cover area and inspect for breakage

04 blue civic

I thought ab that earlier myself. Will test this out one day this week. Thanks again

04 blue civic

My mistake was not testing correct wires. I do have continuity. So does that mean the ecm is the cause of battery light? Alternator shows charging when test with voltmeter and have battery voltage at alternator plus. All fuses of course good.