I installed the new reman last night. I was surprised to find that the O'Reilley reman is a Denso-reman--as far as I could tell. In any case here are my findings:

1. Fast Idle voltage (no accessories): 14.1v
2. Idle (no accessories): 14.3v
3. Idle (all accessories): 13-13.3v
4. Driving under 4k rpm: 14.3v
5. Driving over 4k rpm: 14.1v
6. Driving with AC, Headlights, defroster, radio: 13-13.3v.

I've also noticed that when I put the top down or roll the windows up simultaneously, my idle no longer dips down then back up like it used to when I bought it. In any case, so far so good. I'll report back in a week.

Thanks Geebs for not making this post a complete monologue..lol.

 

It's been about two weeks since the problem has been fixed. Here are the steps I took to resolve the issue (the order doesn't really matter):


1. Check all grounds (Disconnect and clean with wire brush. Torque back down).
2. Check all fuses.
3. Inspect/clean battery post. Clean/Torque down battery terminal connectors.
4. Check both connectors on the back of the alternator.
5. Make an insanely long post on the forum.
6. If the above steps did not fix the issue. Get your alternator tested.
a. Perform a load test on the battery.
b. Check for voltage when idle and with all accessories on.
c. Make sure generated amperage from the Alternator is more than 57.5amps.
7. Replace alternator and or battery based on step 6.
8. ????
9. PROFIT.

 

I am having these same exact symptoms and have checked everything you stated! changed the alternator 3 times!
only thing i have not done is check the amps, how did you check that?


Sorry to other members who may be upset about me bumping an old thread, just looking for answers as ive been at this for a month now

 

After reading my thread--admittedly--I'm still unsure what really fixed it for me. I failed to come back and post that even after the second reman, I experienced the same issue after 4 weeks. Since I had a 6 month old Optima Yellow Top (that was repeatedly tested ok), I was very hesitant on replacing it. Since I ran out of ideas, I went ahead and replaced it with AutoCraft Gold battery. It's been five months and my s2000 has had no electrical issues.

Since I spent quite a bit of money trying to fix this, here's what I've told myself what happened (it may not make sense).

1. The OEM battery killed my OEM Alternator.
2. The Ebay reman alternator (which failed testing) somehow halfway killed my Optima Yellow battery.
3. The O'Reilly Reman alternator was able to carry the Optima Yellow for a short period before it couldn't anymore.
4. The new reman and the new Autocraft Gold battery fixed it.

The reality (most likely) was that it was a battery issue all along. The OEM battery really needed to be replaced but I mistakenly replaced it with a POS Optima Yellow top thinking that it was a superior battery.

***To check for Amps, you need to turn on every accessory on your car (ac, radio, headlights, hazards, etc) which will effectively give the alternator a full load. A dedicated amp meter has to be used to measure amps on the alternator. O'Reillys had this but you have to find a competent tech to do it.

 

When you say you replaced the battery was the optima testing good? I hve the same suspicion of my battery even tho its 3 months old and has passed as a good battery, its the only thing i could think of as being the problem.
did your car reboot the radio as well when it would flash the dash lights?
and did you ever read the cel? mine comes up as p0685 but goes away on its own after a couple days

thanks for responding man ive been at this for a month already with no luck

 

I just wanted to post in here that I had two optima batteries go bad on me and make my car do very weird things. Recently, I reluctantly bought a 3rd, after an advance auto battery lasted 2 years.. Wish me luck!

 

The Optima tested good repeatedly (atleast 4 or 5 times). What battery did you replace it with?

I'm not sure exactly what you mean about the radio rebooting. I do know that I didn't bother putting in the code while I was trying to troubleshoot the issue. I did without it for the entire time and in fact only put the code in a month ago--lol.

My dash lights would either emulate what a bad rectifier looked like--meaning--it would dim the whole cluster and kinda flicker ever so slightly OR it would flicker malfunction indicator lights like VSA, Parking Brake, ABS, !, and EPS flashing on/off/on randomly for a split second.

The CEL i got was also P0685 ECM\PCM Power Real Control Circuit /Open. Its related to the ECU seeing all the MILS turn on and off. Like you, it would clear itself after a day or by diconnecting the battery or clearing it with a OBDII code reader.

 

I replaced mine with a autozone silver battery, probably a bad idea lol but it too passed atleast 5 times as a good battery

And ok yeah if your stock radio was asking for the code it was probably constantly resetting so thats what mine does as well but its a pioneer head unit.

THIS IS THE EXACT THING MINE DOES!

Im gonna try putting on my brother-inlaw's battery because he too has an S and has a known good battery so if my problem does go away I know i got a faulty battery

 

I also forgot to mention that in trying to troubleshoot the battery issue--I had to repeatedly tighten the post connectors. In frustration--I've over torqued the shit out of it. I had to buy battery lead sleeves to ensure a tight fit.