GreenBeast

So I have been chasing a problem the last few months and I have no idea what it could be anymore. It only really happens when the car is in drive and I'm not touching the throttle. Sometimes it will happen in park and reverse so long as I'm not touching the throttle as mentioned before. When it has this problem the voltage coming from the alternator will fluctuate rapidly and randomly anywhere from 12.5v to almost 16v. So instantly I thought that my alternator was going bad. Just put a new one in yesterday and it started doing it again tonight. Now the only thing I can think of is a bad sensor or an ECU problem.

I have went through all the connections from the alternator to the battery ground and they all look fine. I will try to isolate the problem tomorrow but I have no idea where it could be originating from. Any help would be great! Thanks!

t2d2

iTrader: (8)

Have you checked the rest of the Grounds? That's generally gotten the blame for SC electrical problems.

GreenBeast

I have checked them and the main ground to the frame and the block has been re done in the past 5-8 years. Do you know how exactly the voltage is regulated? is it all done by the alternator or is it controlled from somewhere else?

t2d2

iTrader: (8)

Voltage is regulated by the alternator itself, from what I found in a quick search. I've never had to deal with it, so I can't offer much help there.

GreenBeast

Well I'd rather keep from selling the car but if I can't figure this out I can't just keep dumping money into it. I've already chased many other problems around for years.

bigwhite

Your idle has to be above 500 rpm, esp. if the A.C. is on. I would inspect the plug in to the alt. for loose wire or burned connectors on the plug, also that the main battery cable end that bolts on the alt. is not loose.

GreenBeast

I have an intermittent problem with my RPM and Speedometer that has been tracked back to the cluster but when it works my idle never dips below 600-700 during normal driving and even while stopped in traffic. When the RPM gauge isn't working it doesn't feel like it goes below the same mark but I have no way of for sure telling.

Also, when I am stopped at a red light the idle seems to be stressed but the RPM doesn't really change but it sounds like the engine is pulling hard on something and when I have my turn signal on every time the relay fires the engine bogs down a bit as well. Could these problems all be linked to the same thing?

t2d2

iTrader: (8)

Have you had your ECU serviced yet? I had some heavy bogging of the idle, especially with A/C running, before getting that done.

GreenBeast

I haven't had it serviced but it has been replaced in the past threeish years with a confirmed working one. Should that be my next step? Where or how did you get yours serviced?

t2d2

iTrader: (8)

I had mine serviced locally by a circuit board specialist. Tanin and Drift Motion are popular options, and I believe Daryl Geller is somewhat near you.

If the "confirmed working one" hasn't been serviced, it's just as likely to be going bad now. The original capacitors have a ~14 year shelf life.

https://www.clublexus.com/forums/ls4...capacitor.html

TaninAuto

Hi, Tanin Auto Electronix here. We are vendors on the site and would be happy to help out. If you want to send us the ECU, we can plug it in to one of our test cars and let you know what we find.

Give us a call and we can talk more about the ECU when it is convenient for you. We are happy to help out!

GreenBeast

So Tanin would I be able to call tomorrow? I would like to ask some questions on what to do. I was on vacation the past week and didn't want to respond to be honest. This car is my daily so I can't have it down for more than a day or two. Tomorrow I'll re-do the ground wiring and check all the connections on the alternator again.

SC400slide

iTrader: (11)

Where did you get your alternator? In rare cases, the replacement alternators can be faulty. In some cases, the alternator is just a rebuilt until that was previously used. This is why I encourage the purchase of OEM alternators.

Speaking from experience here. Took 4 month for my auto zone alternator to start having issues.

GreenBeast

It's funny you say that. I just swapped an alternator in about a year ago and fearing that it was the classic "part waits until end of warranty to fail" ordeal that always seems to happen to rebuilt parts. So I went and bought an OEM alternator and swapped it in two weeks ago and the problem stayed. I actually just sent the ECU out to Tanin and we'll see if they find/fix the problem. I'll keep the thread updated.

TaninAuto

Absolutely, give us a call today. Depending on where you are located and the time it would take for repair, we can get you a pretty good estimate on how long you would be without the ECU and we can talk about other options too. We do work with customers on this type of issue daily so we will do whatever we can to help out and get the ECU back asap.