Engine Charging Sysetem Light

[theokengineer]

The engine charging system light on my 1987 Honda Accord LX (2bl carb) comes on intermittently. I had the battery and alternator tested and they appear good. Any ideas on why this light might be coming on? It flickers some then stays on, when it does come on.

[dalinxz]

same mine does the same it flashes at idle my uncle told me that out of the three things in the alternator maybe 1 of the diodes is dead so only 66% is being used which is why its flashing and its good enough for now.

[Kabuki]

Diodes? My ass... It's the brushes. Little graphite blocks that keep contact between the electronics and the armature. They wear out over time and can be replaced. If you want them I stock them, and can send them to you.

[Blkblurr]

the light comes on because the alt is not producing enough voltage. This could be due to a slipping belt or too much load on the alt at low speed. Normally a diode failure causes no voltage to be output and a brush failure has the same effect. Have you installed something that uses lots of power like a sound system?

[theokengineer]

the light comes on because the alt is not producing enough voltage. This could be due to a slipping belt or too much load on the alt at low speed. Normally a diode failure causes no voltage to be output and a brush failure has the same effect. Have you installed something that uses lots of power like a sound system?


No, the car is stock with 234,000 miles and the original alternator. I also don't hear a squealling belt. I just replaced the choke pull off and noticed that my rpm's seem to stick (wouldn't go belcow) around 1,800 sometimes even when the engine is warm. Once this was going on with the car not moving and the light was on (light has only come on three times and is currently off), but when the rpm's dropped to 1,000 on its own the light mysteriously went off. Could the idle and light problems be related?

[dalinxz]

CAA did a test the battery is fine and so is the Alternator passed alternator is 14.01 volts. But Its one of the diodes so its only working at 66% which isnt a big deal just flashes little at idle not something to worry about until you lose another.

[lamontlamont]

dude check and clean the 3 prong plug, make sure there is no residue on the alt plug or the wire harness. i had a corroded wire harness and it caused that problem, it destroyed two alts before i figured out the problem, i replaced the wire harness end and i never had a problem since

[Honda-Master]

has the rpm gone up ??? when the alt does not charge properly rpm will go up ,,if that has happened replace alternator ,,,,,,if it has not happened ,,,next time lite comes on, get a big screwdriver and give the alt a good smack if lite goes off replace alternator and by the way use a Honda alternator i know they cost a bit more but they will last for a long long time

[Blkblurr]

Check the wiring harness for corrosion as mentioned earlier. If it looks good and your belts are tight and in good condition, it's most likely your voltage regulator in the alt. For those of you that mention brushes, alternators have slip rings and not brushes. If they have brushes they are called generators and then do not have diodes. Here is a good link to explain this.
http://members.1stconnect.com/anozira/SiteTops/energy/Alternator/alternator.htm

[theokengineer]

has the rpm gone up ??? when the alt does not charge properly rpm will go up ,,if that has happened replace alternator ,,,,,,if it has not happened ,,,next time lite comes on, get a big screwdriver and give the alt a good smack if lite goes off replace alternator and by the way use a Honda alternator i know they cost a bit more but they will last for a long long time


When the light is on the rpm's are up. When it goes off they drop. I will check the connector to see if it is corroded or loose. Thanks.

A Honda alternator is $246 for a remanufactured one versus $85 from other parts stores in my area. Since I only plan to have it another 60-70K miles I think I will save a few bucks if I end up replacing it.

[carotman]

Replacing the brushes and diodes is fairly easy and cheap. I had both fail on my alternator and replaced them. The bearings are a bit harder to do but not impossible.

[theokengineer]

Check the wiring harness for corrosion as mentioned earlier. If it looks good and your belts are tight and in good condition, it's most likely your voltage regulator in the alt. For those of you that mention brushes, alternators have slip rings and not brushes. If they have brushes they are called generators and then do not have diodes. Here is a good link to explain this.
http://members.1stconnect.com/anozira/SiteTops/energy/Alternator/alternator.htm


The belt is tight and no corrosion is on the connector at the alternator.

To remove the alternator on a 1987 Accord do you have to remove the CV axle or can you take the alternator out by taking it behind the engine and out the passenger side?

[87AccordsterLx]

You don’t have to take out the CV axle to remove the alt. Do you happen to have a DVOM or access to one? That would help you out a lot. My guess is that it's a problem with the voltage reference signal or module. Everything inside an alt. is fairly easy to replace. The brushes are easy. Sometimes they can be a pain to put back in but its just annoying trying to get the armature back in while holding the brushes away from it. The brushes shouldn’t be less then 1/4 inch if they are less then replace them. I really don't think that’s your problem though. A diode that burned open would not be intermittent. Try to test for resistance on the ground circuit which would be the case of the alt. to ground on the chassis. Then test for resistance on the charge back wire from the batt. terminal on the alt. to the batt. positive. Current flows back from the alt. to the batt. pos. terminal. Wires are always your best bet to start with while troubleshooting intermittent problems. If your wires on the motor feed and ground circuits are good check the control circuit and the VREF. If your VREF is the problem the PCM/ECM won’t know when to charge more or less depending on load and so forth. That would easily throw an indicator light intermittently.

[logic]

Check the wiring harness for corrosion as mentioned earlier. If it looks good and your belts are tight and in good condition, it's most likely your voltage regulator in the alt. For those of you that mention brushes, alternators have slip rings and not brushes. If they have brushes they are called generators and then do not have diodes. Here is a good link to explain this.
http://members.1stconnect.com/anozira/SiteTops/energy/Alternator/alternator.htm

If you had looked at the link you posted, you would have seen that the BRUSHES contact the SLIP RINGS.....:lol:

[logic]

When the light is on the rpm's are up. When it goes off they drop. I will check the connector to see if it is corroded or loose. Thanks.
A Honda alternator is $246 for a remanufactured one versus $85 from other parts stores in my area. Since I only plan to have it another 60-70K miles I think I will save a few bucks if I end up replacing it.

Unless you're out in the middle of nowhere, there is usually at least one shop in town that will re-build your old one for $30-$50, and you don't have to worry about getting a bad one from the rebuilders that really do a $hitty job.... I never buy new or rebuilt anymore, I get it done right the first time by a local guy that does it for $50.00...

[theokengineer]

There is no corrosion on the connector and hitting the alternator with a screw driver does cause the light to go out. Does this this mean the brushes are probably bad?

Has anyone replaced the brushes with the alternator installed? It looks like it is possible. This would avoid pulling the CV axle.

[logic]

There is no corrosion on the connector and hitting the alternator with a screw driver does cause the light to go out. Does this this mean the brushes are probably bad?
Has anyone replaced the brushes with the alternator installed? It looks like it is possible. This would avoid pulling the CV axle.

I'm sure it could be done, but I'd rather pull the alt and work on it on a table to be sure I did everything right....

I HATE doing $hit over!!!!

[87AccordsterLx]

I remember pulling the alt without pulling the axel. Im not sure if you would be able to replace brushes while it is installed. If you can pull the armature out you should be able to get to the brushes. Good luck with that...

[Kabuki]

Yes guys, it can be done from underneath the vehicle. You will NOT be able to reach from the top!

[theokengineer]

Thanks to everyone who replied. Just to finish this thread out, I wanted everyone to know that I went ahead and replaced the alternator. I then had it tested and although I didn't get the reason why, it was bad. The car is running good now with no problem lights for the charging system.

Concerning changing the brushes with the alternator installed, I couldn't do it. The ground wire on top of the alternator had to be loosened to remove the back cover. I didn't really try, but you need space to loosen the ground and it isn't available (note that the nut sits in a socket so an open end wrench won't do it). I don't think taking the belt off and rotating the alternator aft would allow enouth room either. I could have taken it off its mounting bracket and gotten the ground off, and possibly gotten the brushes out, but decided against this heroic effort for an alternator that is 19 years old with 234,000 miles on it.

[87AccordsterLx]

Good to hear that you got that resolved... :) If you are able to, try to test that alt for unwanted resistance. If it is an easy fix you could make some $$$ if you were to sell it in working condition. Just a suggestion.

[logic]

The ground wire on top of the alternator had to be loosened to remove the back cover. I didn't really try, but you need space to loosen the ground and it isn't available (note that the nut sits in a socket so an open end wrench won't do it).

F.Y.I. That would be the hot wire to the battery, there is no ground wire, the case is ground and completes through the mounting bracket....