Trying to make a charging system checklist here (kinda long)
12-29-09, 09:25 AM
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Trying to make a charging system checklist here (kinda long)
Ok so I'm cursed with the all too familiar battery warning light on the dash flickering on and off; and as of late, coming on and staying on way longer and way more often. I have replaced the p/s pump and alternator with low mileage used units. This is a 93 SC400 by the way.
The p/s pump was so clean I could eat off of it and the new alternator was clean too. I had it tested before installing it and Auto Zone passed it. I installed the pieces and got the car running, and drove perfect for about 3 days, then the light came back on. I drove it for a few more days with it barely coming on at all, and then it got to where it started coming on more and more and staying on longer.
Fast forward to last night, I tore the alternator off again (it is possible to remove it from the top with the p/s pump and pulley, and fan shroud all still in place) and took it to O'reilly to have it tested. It passed all 3 of the tests 3 seperate times. I did notice a little gunk on the 3 prongs on the plug so I scraped them real good, and then cleaned the prongs on the electrical connector on the car as best I could from under the car at 8 at night. I plugged it back in and heard the click noise (like when putting plug wires on a spark plug) and then tightened the main wire down real tight. Got the whole car buttoned back up and went to go to work this morning, and in the roughly 2 miles I drove it before parking it and taking another car, the light stayed on almost the whole time. However, no headlight flickering or loss of power or anything like that.
So here's what I've done so far:
Replaced p/s pump with new no leak unit
Replaced alternator with clean working unit that passed 5 3-part tests
Cleaned connectors on the back of the alternator
Cleaned electrical connector on the car
Checked the 150a alternator fuse and 60a main fuse, none look blown
I'm probably going to replace the alternator fuse anyway. I know people say clean connections and check grounds, if someone could tell me what connections to clean and what grounds to check and clean I'll be more than happy to do it. I'm used to old Datsun Z cars where I could easily see where the grounds go to and where wires connect as everything is in plain sight on those and everythings easy to get to, not so much on this Lexus. This is really baffling me.
The p/s pump was so clean I could eat off of it and the new alternator was clean too. I had it tested before installing it and Auto Zone passed it. I installed the pieces and got the car running, and drove perfect for about 3 days, then the light came back on. I drove it for a few more days with it barely coming on at all, and then it got to where it started coming on more and more and staying on longer.
Fast forward to last night, I tore the alternator off again (it is possible to remove it from the top with the p/s pump and pulley, and fan shroud all still in place) and took it to O'reilly to have it tested. It passed all 3 of the tests 3 seperate times. I did notice a little gunk on the 3 prongs on the plug so I scraped them real good, and then cleaned the prongs on the electrical connector on the car as best I could from under the car at 8 at night. I plugged it back in and heard the click noise (like when putting plug wires on a spark plug) and then tightened the main wire down real tight. Got the whole car buttoned back up and went to go to work this morning, and in the roughly 2 miles I drove it before parking it and taking another car, the light stayed on almost the whole time. However, no headlight flickering or loss of power or anything like that.
So here's what I've done so far:
Replaced p/s pump with new no leak unit
Replaced alternator with clean working unit that passed 5 3-part tests
Cleaned connectors on the back of the alternator
Cleaned electrical connector on the car
Checked the 150a alternator fuse and 60a main fuse, none look blown
I'm probably going to replace the alternator fuse anyway. I know people say clean connections and check grounds, if someone could tell me what connections to clean and what grounds to check and clean I'll be more than happy to do it. I'm used to old Datsun Z cars where I could easily see where the grounds go to and where wires connect as everything is in plain sight on those and everythings easy to get to, not so much on this Lexus. This is really baffling me.
12-29-09, 09:33 AM
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Battery has nothing to do with it.
Matt are you using a DMM to monitor your voltage while driving? That's the very FIRST thing you can must to do even know what the idiot light is trying to tell you.
Matt are you using a DMM to monitor your voltage while driving? That's the very FIRST thing you can must to do even know what the idiot light is trying to tell you.
12-29-09, 09:41 AM
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p.s.
Put a volt meter on the battery and while it's running, it's showing 13.3 volts, with or without the radio on and heat (air doesn't work so no air kicking in). When I revved to 1500, still 13.3, and at 2000 RPM, still 13.3. Right after, put a volt meter on the battery and reading 11.5 volts at rest.
Oh yea, p.p.s.
Radio Shack multi meters are trash. Got a fancy $50 a year ago I guess and tried using it. It was showing 17.8-18.1 volts while running. And tried using it to test a 280Z AFM of mine to see if it was in spec, and it wouldn't get a single reading at all. It's supposed to auto-sense the setting (volt, kilovolt, millivolt, etc) and it kept cycling through all of them and didn't find a thing. Put the meter on it I just used and voila!
Put a volt meter on the battery and while it's running, it's showing 13.3 volts, with or without the radio on and heat (air doesn't work so no air kicking in). When I revved to 1500, still 13.3, and at 2000 RPM, still 13.3. Right after, put a volt meter on the battery and reading 11.5 volts at rest.
Oh yea, p.p.s.
Radio Shack multi meters are trash. Got a fancy $50 a year ago I guess and tried using it. It was showing 17.8-18.1 volts while running. And tried using it to test a 280Z AFM of mine to see if it was in spec, and it wouldn't get a single reading at all. It's supposed to auto-sense the setting (volt, kilovolt, millivolt, etc) and it kept cycling through all of them and didn't find a thing. Put the meter on it I just used and voila!
Last edited by Matt300ZXT; 12-29-09 at 09:45 AM.
12-29-09, 01:03 PM
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*Update*
REALLY cleaned the hell out of the battery cables, tested for continuity on every fuse I could find in the car and started it back up. This time I let it run with the headlights and high beams on and still read 13.3ish, radio and heat on too, same thing. But after about 4 or 5 minutes it started to drop just a little. After about 6 or so minutes of running it got down to low low 12s and then the battery light on the dash came on for a second or two and went away. The lowest it got down to was 11.5ish for about a minute but then came back up and hovered around 12.2-12.4. The battery light came on a few more times but voltage stayed at around the low 12s until I shut it off after about 10 total minutes.
So how common is it for alternators to bench test ok, but in real life usage after the engine gets a little warmer, start to fail?
REALLY cleaned the hell out of the battery cables, tested for continuity on every fuse I could find in the car and started it back up. This time I let it run with the headlights and high beams on and still read 13.3ish, radio and heat on too, same thing. But after about 4 or 5 minutes it started to drop just a little. After about 6 or so minutes of running it got down to low low 12s and then the battery light on the dash came on for a second or two and went away. The lowest it got down to was 11.5ish for about a minute but then came back up and hovered around 12.2-12.4. The battery light came on a few more times but voltage stayed at around the low 12s until I shut it off after about 10 total minutes.
So how common is it for alternators to bench test ok, but in real life usage after the engine gets a little warmer, start to fail?
12-29-09, 01:39 PM
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Voltage regulator can do this, but if the VR is that old the alt is as well. Sounds to me like you half solved your problem on the latest move which didn't involve the alternator at all so why is is still in question, you just giving up on everything else?
12-29-09, 01:48 PM
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What do you mean half solved it? As far as I can tell it looks like the alternator is indeed bad and needs a fresh quality reman. If there's something I'm missing, please feel free to expound upon it.
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12-29-09, 01:59 PM
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Ahh the ol' dirty cables. I'm going to disassemble the stock terminals as much as I possibly can when I have more time and it's not so windy outside. Then clean even more if I can find any funk or corrosion on there. In fact I wouldn't mind just replacing the stock cables with aftermarket high quality ones if I could find a good walkthrough on routing them, where they terminate, etc.
12-29-09, 02:04 PM
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Get some universal cables at advanced or something. I made my own....... https://www.clublexus.com/forums/per...age-issue.html
(see post 10)
(see post 10)
12-29-09, 02:13 PM
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Old battery cables (both the positive and the neg) can corrode and go to hell not only at the battery terminals but WITHIN the cable itself, and at their grounding points as well. These cars are getting up their in age and these old cables do not last forever. If you suspect they could be going south, then they are not that expensive to replace.
12-29-09, 03:31 PM
#12
heres a quick test that worked for me after i changed both my alternator and battery 5 times. grab some jumper cables and clamp one from the BATT terminal on the alternator to battery positive. i had too much resistance/ corrosion on my cable that it was only getting like 7 volts charging. my light went away immediately. you can also but a jumper cable on the negative battery post to a good ground to see if theres excessive resistance on the negative side. GL lemme know if it helped
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