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So I have been reading the forums for a while now and I am finding bits and pieces of the issue I have, but not all together. I am posting this in hopes of some answers to see if I can get away with not paying someone to check the entire wiring harness.

I started the car one day and the battery light and check engine light came on. It showed a 1298 (bad ELM), then two codes for the O2 sensors, the speedometer stopped working and the Alternator stopped working. So I got a new ELM which solved the 1298. Then I found the Alternator fuse was blown. Replaced that and that fixed the O2 sensor codes and the speedometer.

I drive the car for a about 50 or 60 miles (not all at once) and while moving this time the check engine light and battery light came on again. This time no 1298 but the O2 sensor codes and the speedometer stopped working. Again, the Alternator fuse was blown. Prior to this I noticed the charging cycle for the alternator was off. It would be at 14 to 14.4 volts when I started the car until it got warm then it would drop to 12.5 to 12.7 and it would jump to 14s when idling for more than 5 minutes or so. Which is normal, however it would progressively drop from 12.5, when it got to 11.9 to 12.2 it spiked to 14.1 then the fuse blew. Also, when under load it normally runs 13.9 to 14.4 constantly, however now it would jump to 14 or so for a couple minutes then drop back to 12.5 and progressively drop lower.

So, I figured the voltage regulator must be bad. I put in a Denso Alternator for the Honda one that was in there. I know, but I can't afford the 300ish bucks for a Honda one right now. Both bench tested ok. However the problem continued. I didn't drive it to the point of blowing the fuse this time (though I am pretty sure that will happen if I drive it long enough). Once I noticed the strange charging I went a head and started checking grounds and the O2 sensor wires. The O2s had some cracks as I have a header and they sit right up against the AC's heat shield (which I bent back some to cure that). The grounds all seemed clean and well connected and I got 2 new O2 sensors.

However the problem persists. This time I also noticed that periodically the volts will just randomly surge from a steady 12ish reading to 14 for like a second then back to 12s. Also it's no longer giving any voltage increase under load. I can do mechanical stuff myself, but I am not very versed in electrical. As such I am at the point of taking it somewhere to have the harness gone through which is really not in the budget at the moment, so any ideas that would avoid that would be much appreciated. Judging by what I've read I'm guessing no, but I figured I'd throw a hail mary here. I know the default answer here is the aftermarket Alternator is the problem. I am looking for other options to look at assuming that it works as it's going to be a few weeks before I can buy a Honda one.

 
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Ok, I have found out that the EVAP bypass solenoid, canister vent shut valve, and the canister purge valve are on that fuse too. In the last month I had 3 CELs for the EVAP system (2 pending, 1 critical). They came very randomly and I drive a lot. I thought it was a leak based on the CEL description, so I got a new gas cap to being the process of finding the leak. I haven't gotten a CEL for it since the new cap (about a week, maybe 500 miles or so). However, based on the CELs and now the issues I am having, I am thinking perhaps something in the EVAP system is causing the blown fuses and charging issues. I suppose I am looking for affirmation from you fine folks of the Honda forums. Again, give me something to take apart or put back together I am good, but the electrical stuff I'm lost with.

 
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Here is everything on fuse 4 (10 amp) in the under-dash box. Suspiciously everything you're having issues with in addition to cruise.



For starters, check your alternator mounts. It's very common for people to miss a bolt/nut with wreaks havoc on the alternator's ground. There is one bolt up top, one nut underneath that tightens the alternator to the bracket, then a bolt from the bracket to the block. All need to be tight and mounting surfaces clean.

You can always pick up a used Honda alternator from a junkyard to save some money.

I hope those O2 sensors are the proper ones and not some cheap Autozone parts.

This may come down to unplugging one item on that fuse at a time and then see if the issue goes away.

 
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Yes, the Alternator is firmly attached, the belt looks good and is tight. The 02 sensors are NTK (pretty sure they make them for Honda). I took the cruise control out when I put the new engine and inter tie rod ends in and never put it back (i never use it) so that's not the issue. Not sure about the A/F relay. Pretty sure the EVAP must be blowing the fuse. Just not sure it that causing the charging problem.

Also, charges fine before it warms up and when its idle for more than 5 minutes. It only seems to have this problem when its getting rpms, so it makes it hard to take stuff off to see if it affects it. I don't think its wise to attempt to drive around or run it with EVAC parts off the car. I don't have the equipment or the expertise to test them either and a bit short on funds to pay someone to do it. So I'm left with attempting to replace them all.

To make matters worse these parts go by different names. For example the fuse list shows the "Bypass Solenoid" and the "Purge Valve" as different parts, however on the EVAP diagram it says "Bypass Solenoid Valve (purge valve)" as a single part. The genuine Honda part for sale that matches the picture is just called a "Canister Purge Valve" and a Dorman one with the same picture says "Canister Vent Solenoid". So, yeah I am a bit confused about that, lol!

 
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Below is a pic of the EVAP system. There is also a canister shut valve between the canister and the canister vent filter. The canister purge valve is the one that we're interested in since it gets power from fuse 4, it is located on the engine's intake manifold. The purge valve is normally closed, the ECM applies a ground to open the valve once the coolant temperature reaches 158F+. Interesting that you only have issues once the engine is warmed up. You could try unplugging the purge valve and seeing if you have any issues. You will likely get a fault code for the valve but it will not hurt anything to leave it unplugged for a test.

 
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Yeah that makes alot of sense, thank you so much. So the list I was looking at for fuse 4 was wrong. It lists bypass solenoid, purge valve and shunt valve as 3 different parts when there are only 2. 1 at the intake and 1 back at the canister.

Though it starts having problems at like 172 to 180 coolant temp. Generally it sits at 172, when the thermostat opens, for a little while after it gets there, then starts warming up again. That's when the voltage drops from the 14s to 12.5 to 12.8. Could that be the cause or a symptom?

Luckily I have another one of those from the intake that came with the new engine. All the serial numbers match up, so fingers crossed.

 
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I do not know. If the EVAP purge solenoid were shorting or something I could see how that would overload that fuse and cause the alternator to stop charging. Unplug it and drive for a while to see if the issue persists. That is something that can be easily done as a first check.

 
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The other Purge Valve doesn't seem to have cured the problem. I checked the connector and the wires I could get to without tearing up the shield on the harness and they looked ok. Guess I'll try replacing the one by the tank. Beyond that I think I'm out of options here.

 
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What? The canister purge valve is on top of the intake manifold, you replaced it? I meant unplug it and leave it unplugged. See if the fuse blows and you still have charging issues.

 
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A couple months ago I switched engines and it came with a intake on it. So I took that purge valve and replaced the one in question. I will try running it with it unplugged now. I thought the other valve by the canister also ran off the same circuit, thought if this one wasn't the cure that one might be.

 
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I tried driving it with the purge valve unplugged. At first it was no different. Running a 12.3 mostly with dips to 12.1. Then it jumped up to 13.9 with a couple brief drops to 13.8 for about 5 minutes or so. Then back down to 12.3. Still not increasing volts under load. No blown fuse as of yet either way.

Also, before unplugging it, during, and after it is now randomly activating the battery light when at idle. When I hit the gas it turns off but shows no change in voltage with the light on or off. I hate electrical *sigh*

 
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In addition it did not throw a code for the unplugged purge valve. Not sure if that means anything. Also, it's now down to 13.7 to 13.9 when it is charging after idle for 5 minutes instead of the normal 14.0 to 14.4.

FYI, I haven't done any work under the hood since March 15th when I did the head gasket. It had been running fine, this just happened out of the blue. I did do some suspension stuff, but don't think any of that had anything to do with this mess.

 
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isn't this a ELD issue?
Electric load detector

 
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ELD was replaced already, unless it's a bad part.

 
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Wouldn't it throw a code if the new ELD was bad?

 
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Was it a quality part? Or a cheap parts store replacement?

 
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Well *hangs head in shame* it's from Nappa. It was out of stock on Honda Parts Now. The local dealership wanted 140 dollars plus like 5 days to have it shipped and Amazon had a Honda one that was actually cheaper than the Nappa one but would take 3 weeks to get here. I literally can not work without the car, so I took the same day fix option.

 
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There is a way to bypass the ELD. Looks like a 820 ohm resistor from the green/red wire to ground fakes a high electrical load putting the alternator in high output mode. Not sure if leaving it unplugged would default to charging with a fault code or if it would shutoff the alternator. I replaced mine 5 years ago, bought a Honda part on Amazon for like $30.

https://www.civicforums.com/forums/2...ld-bypass.html

I would probably unplug the ELD and see what happens. Maybe it will consistently charge and we can assume the ELD is bad.

Edit: Honestly this could just be a combo issue of non-OEM alternator and ELD as well.

 
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Well, I am on my way to the salvage yard to pull a few ELDs to test that out. Also will put the Honda alternator back on since they both bench tested fine and are suffering from the same issues, I am betting the Honda one is fine.

 
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I think that will be a good test. With any luck a proper ELD will let the alternator work correctly.

 
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Yeah well luck clearly hasn't been a friend of mine lately, lol! Thanks for your help thus far, I really appreciate it. Electrical really is not my strong suit. I'll post up on how it goes.

 
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I ran a short test and the salvage yard ELD seems to have worked. Tomorrow will be the big test running it for 70 or 80 miles. It's now charging again under load. However it is a few ticks off what it normally does. 14.1 to 14.4 before warm up normally, 13.9 to 14.2 now. 12.5 to 12.7 normally while running. 12.3 to 12.5 now. 14.0 to 14.3 under load normally, 13.6 to 13.9 now.


It's also still randomly spiking from 12.3ish to 13.5ish for like a second then back down to 12.3ish. The battery light still comes on randomly at idle with no change in voltage and goes away when I hit the gas. I think that may be due to the aftermarket Alternator, so I am going to put the Honda one in and see how it does.

 
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I agree with this.

 
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me likes your way of testing the ELD

 
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Indeed! Now I have back ups just incase. I am a touch concerned that the Honda Alternator may have started this whole mess despite the bench test since it never popped the fuse with the other Alternator.

 
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Could be. I wouldn't trust a part stores bench test of an alternator.

-Something in alternator shorts and pops the fuse.
-Fault code for ELD and everything else, they are also on that fuse which makes sense. ELD could have also been bad already.
-You replaced ELD and fixed the fuse but alternator keeps shorting occasionally, blowing the fuse.
-Replaced the alternator with non-OEM which stops the fuse from blowing but still causes charging issues (because aftermarket part).
-Replaced ELD with Honda part, still some charging issues due to alternator.

Go check the junkyard for an OEM alternator then return new one to parts store?

 
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I didn't buy the aftermarket one, a friend of mine gave it to me. I just keep it around for emergency. Again, I need the car for work, I can pop a Alternator in on the side of the road in about 15 mins if need be. Given a few header burns, lol.

My current plan is to keep it in there for the weekend because it's busy time for work and I can't afford the car to be popping fuses and having issues. It's working, all be it a little lower volts. Then Sunday I'll try out the Honda one if it pops the fuse I'll go ahead and head for the junkyard or order a new Honda one budget permitting.

The O2 sensors had some pretty bad wires and a part of me is still thinking that's what popped the fuse and perhaps killed the ELD. It's hard to say because it doesn't pop the fuse immediately. Fist time was when I started it, second was while driving after 50 or so miles of running and like turning it on and off 4 times. I miss my old cars that had like 10 wires in the whole car and no computers right now, lol.

 
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And yes, I have a reserve Alternator and Starter in the trunk at all times, lol!

 
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With this generation, I hope you have a spare head gasket back there too

 
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Actually I do have a spare gasket and head along with some other assorted parts, fuse, relays and whatnot. I have a Honda gasket I had to wait 3 weeks for that's waiting for the Vincos one I put on to fail and I have a rebuilt head from my old motor. Though I'm still not sure why I couldn't get that engine to work with a new Honda head gasket and the rebuilt head. However I do not keep that stuff in the trunk.