MngreLMatt

Howdy guys,

Still doing the Alternator. After reassembly, and hooking up the mulitmeter to the battery it is over charging. Right after I start it up it reads 17+V and continues to rise -so I immediately turned it off. There must be something with the regulator going on. I took it out again and readjusted a bolt that looked like it might be used for grounding purposes on the rectifier/brushes/power connector.

I'm really not sure what's going on. This may be a long shot but if anyone has an idea it would be greatly appreciated. When putting the alternator back together I must have missed a small detail with some of the regulator bolts as for some reason it isn't doing its job. The regulator was working before the rebuild keeping me in the 14.2-.4 range. I think I am missing something here. Maybe I missed a ground somewhere. I don't understand how the regulator was working just fine before taking it apart and now is not.
So close, but yet so far away. Any help is greatly appreciated.

Thanks in advance


Matt

Yamae

Sounds like the regulator is not properly attached to the alternator body or damaged.
There are 5 screws. 2 longer screws hold the regulator to the alternator body and the ground connection is done by these. Shorter ones connect the regulator to the stator, the field coil and B+. Check these 5 again. When the field coil or B+ are not connected, the voltage should be very low and when the body is not grounded, the voltage is very high but there are 2 screws and the possibility is low. When B+ and the field coil terminals are short circuited, too high voltage is generated because the field coils gets too much current.

MngreLMatt

Yamae,

Thank you very much for the help. Can you tell me how to test it with my Multi-meter to test it for resistance so that I don't have to put it back on the car every time I want to test the alternator? This would greatly reduce the time it takes to troubleshoot the system. I have the ohmeter setup accordingly, I'm just not sure where exactly to place them to test for my problem.

Thanks again,

Matt

Yamae

You can access the alternator from the back side of it. I even once removed the brush unit without removing the alternator from the engine. You need to move it or should I say to rotate it about 15 degrees releasing bolts slightly. Remove the rear aluminum cover and you can access both the regulator and the brush unit.

A passive check by a multimeter can't check the regulator well enough but when it is badly damaged, you can check some extent.

I currently don't have a spare regulator for a Celsior but I have one for a smaller car and it should not be different too much. Below are the actual measurement results for a smaller car Caldina which may not be common in US market.
The resistance between the ground tip and stator is 0.42k ohm.
Between stator and F is 214k ohm.
Between F and B+ is 278k ohm.

The multimeter I used was a Fluke 8060A which is the most expensive one I own. You can find a photo of it at the page below. The red probe is always touched to the left side.
https://www.clublexus.com/forums/ls4...-symptoms.html

MngreLMatt

Thanks yamae, I have the alternator off the car right now and will do this test. Thank you again very much.


Matt

MngreLMatt

Ground to stator reads 418ohms.
stator to F reads 980ohms
F to B+ reads 568ohms.

I used a craftsman digital multimeter similar to the one listed here.
http://www.amazon.com/Craftsman-34-82141-Digital-Multimeter-Functions/dp/B000X5TSUA


My resistance range is far too high compared to what you listed. I'm not sure if it is supposed to be or not. Even though your ratings were taken from a regulator that came from a smaller car I don't think the ratings for the Celsior would be 4-5 times as much. I'm not sure what I could have done to the regulator between taking it apart and putting it all back together. I was very careful with the parts but it looks like I managed to break it anyway.

MngreLMatt

http://store.alternatorparts.com/par...ternators.aspx

I see this one. It says "w/o LRC". This meaning I guess that it does not have Load Response Control. I'm not sure if this is how it is supposed to be and they are just listing it that way for clarity or if it is actually different than the orginal. The part number matches perfectly. 27700-50030. It says it is a replacement for 2004-98 Lexus

MngreLMatt

I ended up getting an OEM regulator and brushes while I was at it. The slip rings did not look bad. There is an extremely subtle indentation in the rings but I am talking maybe the size of a hair strand.

I'll put the new regulator and brushes in tomorrow. I can't see any other reason for the over charging problem. Anyone else heard of something other than the regulator going bad causing over charging ? I mean there isn't too much to the alternator once you open them up really. Rotor, slip rings, stator wiring rectifier to get dc and a regulator to keep it all in check per say.

At any rate I have brand spanking new bearings, New regulator and new brushes. That can't be half bad. It was a definite learning process and even though I don't have a whole lot of cash it is hard to put a price on doing something and learning a little bit on the way.

Thanks again for the help you all. By the way, are there any of you in Southern California that like to work on cars? I think it would be fun to drive over to help one of y'all with your car if you needed an extra hand or two for any given job. Just an idea.

Feel free to contact me via PMessage if need be. I'm in South Orange County

I'll report later and maybe even do a tear down video of the alternator so people like myself, who had no previous knowledge could see what's going on in those mysterious things.



Matt

MngreLMatt

Well gurus, replaced the regulator and brushes. The alternator is still overcharging the same way as before. Truly stumped now. Any ideas out there?

lexmoose

Here's some ideas

Bad multimeter? what the voltage on your battery with the car off?

Multimeter set to AC instead of DC

Bad ground? confirm by using jumper cable from the alt chassis to the neg battery terminal.

Damaged connector? If you unplug it what happen?

KA8

iTrader: (1)

I had overcharging problem. I was retrieving CEL code and I forgot to unplug paper clip from obd port and cranked the engine, immediately alternator started overcharging and my ecu was toast. Also my starter went bad in a few months and I think this caused it. Most likely you short something and burnt something inside the alternator. I tried rebuilding it, new voltage regulator, you name it I tried it. Ended up buying a good used one from junk yard for $50 and problem solved. I would try good unit from junk yard or new oem rebuilt unit.

MngreLMatt

Hey guys one more question for you. Do you think it is possible that not having power out connector (that connects to the stud coming off of the rectifier) sandwiched in between the two nuts on the rectifier terminal(stud) could cause the over charging issue? The thing is, I didn't have both of those nuts connected before. I had it so that the power out cable sat on the plastic and then there was just one nut sitting on top of that. I looked at a good alternator and it has both of the nuts on there sandwiching this cable.

What do you guys think?

MngreLMatt

The weird thing is that it wasn't overcharging before I took it apart to do the bearings. I even ordered a new regulator because I thought that might be it. Maybe the new regulator was bad as well? Or possible that they are both fine and the problem lies in my previous post? I'm lost at this point.

I hate this. A huge portion of the reason I do my own work on the car is so that I can learn how it all works. When stuff like this happens you lose the sense of closure and learning. Really feels like a waste. The good news I guess is that I can take out and put back in the alternator in about an hour including clean up.


To clarify, the voltmeter I was using was working correctly. I'm not exactly sure about checking the ground. The test that I did from neg battery terminal to the outside of the bad alternator showed 4.4. I'm not sure I even did the test correctly.

If you guys have anything more as far as ideas I'm all ears.

Matt

lexmoose

A 4.4 ohm load between your negative battery terminal and alt chassis is not normal. Is it the source of your problem, not sure, but you should try a jumper cable between the alt chassis and your negative battery terminal to see if it help.

MngreLMatt

I'm sorry chouinard, I misunderstood. When testing it the way you described I can't remember now what setting it was on. The only other setting I used was DC, if I did this same thing with the DC setting is it possible to get that reading?