TOTAL HONDA NEWB, First post. Battery light on, alternator charging.
 

Hey guys, just like the title says i am brand new here. i have been searching for an answer for my issue for a while, and i can see many people post a similiar issue, but i have yet to find a solution.

2002 civic 1.7 LX AT. i am fixing this for a buddy. the alternator failed, blew the ecu, and turned on about ever CEL on the dash. I put a new alternator in (the last one was frozen stuck! i could not turn it!) this allowed the car to drive, but it was in "limp mode" no tach, no temp guage, not shifting, all the CEL's on, etc...

So i installed a new ECU, swapped the chip and transponder, and now it is running perfect! no CEL's, no green key light. all the gauges work, i am ready to call this a job well done EXCEPT the battery light is still on.

i have checked the voltage on the alternator and it is 13.5+ idling and 14.5 at about 2,000 rpms. this is all correct according to several guides. and according to the honda owers manual the only reason for the battery CEL to come on is in the event the alternator is not charging. i have checked all the fuses, in cabin and underdash, all are good. i have also checked the alternator, the belt tension, and all of the grounds. all look good.

Can anyone help me get rid of this light?

Re: TOTAL HONDA NEWB, First post. Battery light on, alternator charging.
 

anyone?

Re: TOTAL HONDA NEWB, First post. Battery light on, alternator charging.
 

Leave the engine running with the battery warning light on.

Unplug the 4 wire connector from the alternator.

If the battery warning light stays on, it's not the alternator.
If the battery light goes out, it's a bad alternator.

Also, allow up to 24 hours for replies so all the regulars have a chance to see your posts. This place isn't like a chatroom very often.

HTH

Re: TOTAL HONDA NEWB, First post. Battery light on, alternator charging.
 

sorry for my impatience. thx for the advice, i will give that a shot this evening. i got a remanned alternator from Napa....i've been burned by autozone ones in the past, always heard napa had the best ones.

anyway, i will try the test as stated, and worst case, i may swap the alternator again.

thank you for the feedback!

Re: TOTAL HONDA NEWB, First post. Battery light on, alternator charging.
 

I just fired up the car and disconnected the 4 wire plug. The battery light stayed on. Do I just need to start tracing the wires from the alt to the battery and beyond...any common fail areas to look for? I already started with the grounds and they look good.

Thanks guys.

Re: TOTAL HONDA NEWB, First post. Battery light on, alternator charging.
 

Sounds like now you need to figure out if the PCM is keeping the light on, or if the gauge cluster is keeping it on, or if the MICU is keeping it on.


Service manual, alternator and controls testing?

Got codes from the PCM? Does it communicate at all or is it brain dead? Does it show any alternator controls in the data list?

Gauge sweep/light check/cluster self diag tests?

Multiplex tests in the service manual?

Re: TOTAL HONDA NEWB, First post. Battery light on, alternator charging.
 

I replaced the pcm because the last one was not communicating. This one seems to be working fine, and there are no codes.

How would I test the cluster and micu?

Also I tried doing the self diagnosis test where you hold the trip rest button in for 10 seconds , and turn the ignition on. Nothing happened.

I have not tried multiplex testing or anything else.

Re: TOTAL HONDA NEWB, First post. Battery light on, alternator charging.
 

That action just resets the maint req'd light (oil change reminder).

Search the forum for cluster self test and multiplex testing, and check your service manuals if the forum doesn't have it.

Does the car have any other odd electrical symptoms?
Beeper inop? Courtesy lighting inop? AC inop?

Re: TOTAL HONDA NEWB, First post. Battery light on, alternator charging.
 

okay, my odyssey is the only other honda i typically work on, and frankly that thing needs so little maintenance it's awesome! the oil change reset/trip button....i didn't think i was going to do much with that.

as for the A/C, beeper/courtesy lights, i am not sure. i know the headlight buzzer comes on if the lights are on with the key out. i just don't know much about the car as it is my buddies kids car.

i will search up this info, and let you guys know. thanks for walking through this with me.

Re: TOTAL HONDA NEWB, First post. Battery light on, alternator charging.
 

Checked some serv info and a note I made....

From a note not in the service manual:
Turn key on but don't start the engine (I had this backwards earlier). Unplug the alternator 4 wire plug. Does the charge light go out? If it goes out, replace alternator.

So if it fails that above with the engine NOT running, the alt is bad (bad regulator keeping the light circuit on)).

If no success there, continue
From the manual:
Turn key on, does the charge light come on?
Yes

Start engine, does charge light stay on?
Yes

Do gauge cluster self test, does the charge indicator flash?
(your answer determines the next steps)

Re: TOTAL HONDA NEWB, First post. Battery light on, alternator charging.
 

I will redo the 4 wire plug in the alt according to the updated info you gave me. I am getting to work on this today as Mondays are my off days....and this weekend was crazy!

I printed off the testing procedures you recommended above, then I left them at work :/ I will start tackling all of this today.

Thanks for all the help!

Re: TOTAL HONDA NEWB, First post. Battery light on, alternator charging.
 

So the red battery light stays on with the key "on" but engine not running, with 4 wire plug disconnected.

Also the car has the courtesy chime with the key in, but no lights... the interior lights work if I push them in. The cluster dims with headlights on. A/C works, radio works, etc...

I will be doing the cluster self diagnosis test. As for the multiplex, from my research I do not seem to have most of the issues associated with that. BUT I am not sure what the "main fuse" located on the in cabin fuse panel is. All the fuses I have checked have been good.

Please advise.

Re: TOTAL HONDA NEWB, First post. Battery light on, alternator charging.
 

I have been trying this for the cluster self diagnosis test, yet I can not get the car to run the test.

"after you check all connections and bolts run self diagnostic on the cluster: With the car off and the keys in the ignition, 1. Push and hold the trip-reset button 2. Turn the lighting switch on 3. Turn the ignition switch on within 5 seconds 4. Turn the lighting switch off, then on, then off again. 5. Within 5 seconds, release the trip/reset button, then push and release it 4 times repeatedly. This will run a self-contained diagnostic procedure".

Re: TOTAL HONDA NEWB, First post. Battery light on, alternator charging.
 

Before self test, check fuses
#9 in the engine compartment fuse box and
#10 in the dash fuse box

Self test:

1. Push and hold the trip/reset button. (make sure it actually works before staring this test)
2. Turn headlight switch ON.
3. Turn the ignition switch ON (do not start the engine).
4. Within 5 seconds turn the headlight switch OFF, then ON and OFF again
5. Within 5 seconds release the trip/reset button, then push and release the button four times repeatedly

Self test initiates if you did it right, gauge needles sweep and warning lights flash
Trip/reset button will start the beeper check and start the gauge sweep test




HTH

Re: TOTAL HONDA NEWB, First post. Battery light on, alternator charging.
 

Sorry for my delay these last couple of days.....busy, busy!
thx for breaking down the gauge sweep test, i don't think i was doing it right.

as for the fuses, i have checked those specifically, and they are good. i went ahead and checked all of them, and they are all good too.

i replaced the alternator because it seemed like the voltage regulator was bad based on a diagnostic reading i got using my buddies OBD II scanner. i put a new alternator in and the battery light is still lite.

i have the multiplex testing procedures.....should i start going through those?

Re: TOTAL HONDA NEWB, First post. Battery light on, alternator charging.
 

What did the battery/charging indicator do during the gauges self diag tests? Did the indicator blink with the rest of the lights or did it remain on steady?

Re: TOTAL HONDA NEWB, First post. Battery light on, alternator charging.
 

It blinked with the test of the lights. The only one that stayed steady was the oil light.

Re: TOTAL HONDA NEWB, First post. Battery light on, alternator charging.
 

Next steps

Turn ignition off
Disconnect alternator 4 wire plug
Turn ignition on (do not start the engine)
Check voltage between blk/yel and ground

Is there battery voltage?
If no, check fuse #4 in the dash fusebox
If yes, then you're into checking circuits between PCM and alternator, NOW you need a service manual.

Re: TOTAL HONDA NEWB, First post. Battery light on, alternator charging.
 

if i remember correctly these cars don't seem to like after market alternators they will usually set off the charging light for some reason.

Re: TOTAL HONDA NEWB, First post. Battery light on, alternator charging.
 

Where do you get an OEM Honda alternator? Stealership part? Seems silly that a standard Napa remanded alternator would not work.

Re: TOTAL HONDA NEWB, First post. Battery light on, alternator charging.
 

I will try this tomorrow. I have done the "pull the plug while running" test and the light always stayed on. I have a Haynes manual, would that cover the testing procedure I need to follow?

Re: TOTAL HONDA NEWB, First post. Battery light on, alternator charging.
 

I can't answer that, I have no way to compare it with the FSM.

Re: TOTAL HONDA NEWB, First post. Battery light on, alternator charging.
 

I did the test. There is power at the yellow/black when it is disconnected.

Is the next step to go thru and check to see if there is a circuit that is energized that is not supposed to be? Please walk me thru.


E zone Thx for all your help.

Re: TOTAL HONDA NEWB, First post. Battery light on, alternator charging.
 

any chance this is the eld giving me problems? that would be easy but I guess that would throw a code....

I keep coming back to the fact that there are no engine codes or blown fuses.

Re: TOTAL HONDA NEWB, First post. Battery light on, alternator charging.
 

The next checks are testing continuity between the alt wiring and PCM, and checking for shorts to ground on any of them, and stuff like that. My manual has drawings of PCM connectors and gives step by step what to check and how. Your manual should have all this too if it's halfway decent.


It won't be an ELD problem.

You swapped a different PCM?
What's the part number on it?
Was it identical to the original?
Send me the VIN of the car, I wanna check the part numbers on it

Re: TOTAL HONDA NEWB, First post. Battery light on, alternator charging.
 

I swapped a different pcm, I could not find the exact match, but I found one that was very close. Mines an 02 auto lx. The replacement is an 01 auto lx.

The Vin is 1hgem22572L105233.

Re: TOTAL HONDA NEWB, First post. Battery light on, alternator charging.
 

This should work, right? Is there a way to know which circuits should be energized and which should not? Once again thanks


Attachment 90555

Re: TOTAL HONDA NEWB, First post. Battery light on, alternator charging.
 

Looks like a wire diagram of the charging system.

Use this in conjunction with the service manual?
You can see where the multiplex unit is involved between the PCM and the gauges. The 2 lines in and out of it are part of a communication bus, data is transmitted over it and you can't measure voltage on it. Much of the gauges and idiot lights operate using only data from the bus.

Voltages....refer to the troubleshooting stuff in the service manual. In the diagram the 12v powered stuff should be obvious as are grounds, but the rest.........



Here's a handy PDF on Hondas charging systems I just found, this explains better than I can:

https://www.google.com/url?sa=t&rct=...5wyG_ukAxxeDxA


"The voltage regulator utilizes five terminals: Ignition (IG), Control (C), Field
Reference (FR), Battery, (B) and Lamp (L). The B terminal is the high current
circuit that's responsible for charging the battery"

Re: TOTAL HONDA NEWB, First post. Battery light on, alternator charging.
 

Looks to me like I should check the white/red, green, blue from the alt to the pcm? If there is a short in those styles that could effect the charging/trigger the light?

Re: TOTAL HONDA NEWB, First post. Battery light on, alternator charging.
 

The basic tests are: Disconnect the alternator harness and the PCM harness, then do the continuity tests for each wire, and check each wire for a short to ground or power.


The alternator grounds the "L" circuit to turn on the warning light, so if the "L" circuit were grounded elsewhere between the alt and PCM that would cause the PCM to issue the command to the cluster to keep the light on (in theory).

I see your book diagram posted doesn't give terminal numbers at the PCM. You are gonna need those.

At the PCM:
Circuit L goes to connector and terminal B10
FR is B13
C is B18
ELD input is E15
Communication BUS is E24




I got a stupid thought.....if you disconnect the PCM harnesses and then turn the key on, does the charge warning light still stay lit in the cluster?
(wish I had one to double check this on, but I don't.)