DIY:CHARGING SYSTEM FULL DIAGNOSTIC(alternator/battery) - Page 4 - Lexus IS Forum
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post #46 of 71 (permalink) Old 11-22-2015, 11:20 PM
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Please help!

HI Jason,
Thanks for writing back. If I post a photo, could you tell if the alternator fuse is blown? Or else can you please tell me how to test if the alternator fuse is blown? Is your vehicle also a 2007 IS? If it is that would make it easier for you to check out a photo of my fuses in the black box near the firewall on the passenger side to see what you think.
What other problems could cause my car not to start after new battery installed? It definitely wasn't hooked up backwards unless the manufacturer labeled positive and negative wrong which I doubt! What you even heard of a car not starting after new battery installed when it seemed like it just needed a new battery? I am just trying to trouble shoot what is going on with my car as it has never had problems before and gave no notice of this. It had the original battery which made it eight years old so expected that it would be in need of replacement. I have had the old battery tested and was told it definitely needed replacement. Car has low mileage so I can't think of anything else that would be causing it not to start!
Thanks again for listening! I will try to take a good photo now and post it soon. I am not quite sure how to send a photo though. Could you please give me instructions? I have a few good photos of this.
Susan
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post #47 of 71 (permalink) Old 12-29-2015, 10:42 PM
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I might as well post this in here, I'm not getting anywhere to fast on my own. I've got an '02, completely stock as far as I can tell, although I'm not positive that the PO wasn't messing about. Good optima blue top battery. Bad ballast on passenger side. Here's my problem:
Car starts fine and runs great aside from this problem. I was city driving one evening and noticed my battery light flickering, especially when making a turn from being stopped(turning the steering wheel at low revs) The volt gauge on the dash was showing me sub-12v so I assumed I was running off of the battery without help from the alt, aka bad alt. Got home without trouble, put 'change alternator' on my mental list of things to do during the holiday, and kept pushing my luck. Next time I started the car up, it seemed back to normal on the volt gauge so I continued driving it with mild trouble of the same sort off and on. Seemed to be happening consistently when I was driving at night (headlights/fogs on) using accessories, heater, rear defrost, heated seat.....finally decided I'd had enough and I'll just replace the alt. I've been down the dying alt route too many times to want to get stuck somewhere. Bought a lifetime alt from advance auto, installed and turned in the factory unit as a core. Few days later driving at night, same shit. Returned new lifetime alt for another new lifetime alt, drive, same shit again. Bought a new battery just to try it, same result so I started testing the system >
Start up, battery reads ~14.4v, rev up and goes to around 14.6v. Turn on heater full blast, dips a little but comes right back up. Start turning accessories on one at a time, rear def, hazards, wipers, heated seats, headlights, high beams, and it recovers after each one, down to about ~13v, where it seems to click over to running without the alt, dropping to ~11.7v with accessories on and ~11.9v once everything is off. Once it has 'clicked over' to this drop, the voltage doesn't recover when you rev, it drops slightly. To me it's acting like a relay is taking over, but I have no idea which it would be. If I shut the car off and leave it for 5 minutes or so, it resets itself back to normal operation, starts fine and runs back up at 14.4v. The only thing that's out of place is that while testing I've blown the passenger side(R) 15a fog light fuse twice. I pulled the connector and tested the plug, got a beep telling me there's continuity between the red/yel wire and the wht/blk. Also the same for the marker light in the bumper that comes from the same section of harness, continuity between the green and wht/blk, and obviously continuity between the grounds of these plugs. I looked at a wiring diagram I found online and it shows the DRL resistor in line on that circuit, so I disconnected the plug and tested the unit across the pins, came up with .8 ohms. That's where I stopped basically, my hands were cold and I couldn't find a spec for resistance on my phone in a few minutes of searching. Only other thing to note is that my A/C light blinks, if I turn on the heat it comes on automatically so I press once to shut it off, stays off for a few seconds then comes back blinking. I'm not positive that these are related, but if I can't find any problems with the fog light it's where I'm going to look next. Any insight would be awesome. Cheers

Last edited by Cruuz; 12-29-2015 at 10:50 PM.
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post #48 of 71 (permalink) Old 12-30-2015, 03:31 PM
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That sounds like a bad regulator but you've eliminated that with two new units. Does the voltage go up at all in higher RPMs when it hits sub 12v levels? The AC blinking is odd, did you try a full load up test with every system on except to the heater/AC and see if it drops below the minimum test threshold?
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post #49 of 71 (permalink) Old 12-30-2015, 07:16 PM
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I guess it could be a second bad unit, but I can't test it besides pulling it and taking it over to be bench tested. Taking the car over would be a waste of time. I should say, I could test it. I was just hoping to not have to again. I think I am going to pull it and take it over, can't hurt I guess right. I'll just reserve the right to be highly irritated if it tests ok Lolz
The voltage doesn't rise at all once it's clicked over to below 12v, it drops slightly with the revs.
I do need to try load testing it without turning on the heater/AC, but I'm guessing it won't be enough to trip it without the load of the blower running. It's really too bad that they're linked, that's soooooo damn annoying

Last edited by Cruuz; 12-30-2015 at 07:23 PM.
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post #50 of 71 (permalink) Old 01-06-2016, 07:07 PM
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Progress update:
Fog lights, turn signals all check out ok. I was mistaken in my previous statement thinking the fog light was blowing a fuse. The bad passenger side ballast was blowing it's 15A fuse, so I unplugged the connector to it and will leave it off until it gets replaced.
The current alternator on the car checks out, passes all tests listed here, so I've basically ruled it out. The only thing I found new was on the 3 wire plug. The center wire, red with blue stripe, is only getting 11.85v with the key in the 'ON' position. So the regulator isn't getting full juice? The battery was at 12.35v at that point. Now I have to figure out how/where to chase that issue down. Anyone care to chime in?
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post #51 of 71 (permalink) Old 02-23-2016, 07:24 PM
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I'm getting a 1.9A drain. Pulled every fuse from each box on both sides inside the car and both boxes on either side under the hood. No change.

Any other suggestions? I pulled the relays too except 3 I couldn't disconnect.

Not wanting to go to the dealership for this....
(car is stock)
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post #52 of 71 (permalink) Old 02-23-2016, 07:45 PM Thread Starter
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Quote:
Originally Posted by Boofster View Post
I'm getting a 1.9A drain. Pulled every fuse from each box on both sides inside the car and both boxes on either side under the hood. No change.

Any other suggestions? I pulled the relays too except 3 I couldn't
disconnect.

Not wanting to go to the dealership for this....
(car is stock)

1.9A is obviously way way too high. You will.have to trace it out, follow the positive battery lead to the nearby jbox. Did you full the higher amp fuses too? I would download a copy of the diagnostic manual, which is available on the stickies. A bad alternator with bad diode leakage could cause this but seems unlikely, however, it is one possible route. So you have the EFI, Radio#1, and Dome pulled? Sounds like a load of a light bulb or something, surely enough to kill the battery within hours. Don't take it to the dealer, you just need to verify what is pulled and dig deeper. You should see 0.050A after 5 minutes, not 1.9A.

'02 IS300 MSM LSD
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post #53 of 71 (permalink) Old 02-23-2016, 08:50 PM
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I pulled every fuse I found....but I did them one by one. Is there a difference if I pull a bunch instead?

Yes, I assumed this was my fail of something I plugged in so those were the first tests but no luck.

Would the alternator be failing? What's a good way to unplug it?
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post #54 of 71 (permalink) Old 02-23-2016, 09:10 PM
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Quote:
Originally Posted by Boofster View Post
I pulled every fuse I found....but I did them one by one. Is there a difference if I pull a bunch instead?

Yes, I assumed this was my fail of something I plugged in so those were the first tests but no luck.

Would the alternator be failing? What's a good way to unplug it?
I had an Alternator power diode assembly go bad once and it drew lots of amps when hot, and flattened the battery overnight. I suggest you disconnect the main power lead to the alternator if you cant find another way to disconnect. Good luck.

2004 IS300 MSM LSD Manual ..Hail damage written-off so now grand daughters car
2003 Pathfinder SE 4WD
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post #55 of 71 (permalink) Old 03-11-2016, 11:01 PM
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It was a bad battery problem after all. Apparently Optima's are not what they used to be

Thank you all for the help.
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post #56 of 71 (permalink) Old 03-12-2016, 08:14 AM Thread Starter
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Quote:
Originally Posted by Boofster View Post
I pulled every fuse I found....but I did them one by one. Is there a difference if I pull a bunch instead?

Yes, I assumed this was my fail of something I plugged in so those were the first tests but no luck.

Sorry for the late reply, there are main and sub fuses. They are located by the battery and kick panels. I would pull one main at a time or each individual until the current drops. You had a 1.9A draw which is equivalent to a 24 watt light bulb on continuously.
You NEED to make sure you find that draw and get it out of there or your new battery will die within hours. Remember there are certain fuses that draw car off, such as the EFI, radio #1, etc. Needs to stabilize under 50mA, that's a must.

Would the alternator be failing? What's a good way to unplug it?
Quote:
Originally Posted by Boofster View Post
It was a bad battery problem after all. Apparently Optima's are not what they used to be

Thank you all for the help.
You can find out with a good DMM and using the tests provided. Test for diode leakage(which can cause a draw), especially with a hot engine. Check your grounding and other tests. Worst case, you'll have to pull it for Bench test, which will also only additionally test for load output.

I don't think it's your battery, unless the load test says it has failed. As long as you have a D34-78(yellow) or like, and it's stored to full charge (12.6v+) then you shouldn't have problems. I have ran that battery for the last 4 years so far and my last one lasted 5˝ years. But a hard parasitic ground will kill any battery in a short amount of time.

'02 IS300 MSM LSD
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post #57 of 71 (permalink) Old 03-12-2016, 03:20 PM
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I am pretty sure I did the test right so either my meter is crap or I don't know. Dealer had to do a recall so I let them diagnose it and they said it was pulling 0.4 amps and the battery did not pass the load test. Using Optima Red here and it only lasted 8 months. Maybe I'll try a Deka or Odyssey next time.
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post #58 of 71 (permalink) Old 03-12-2016, 03:26 PM Thread Starter
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Quote:
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I am pretty sure I did the test right so either my meter is crap or I don't know. Dealer had to do a recall so I let them diagnose it and they said it was pulling 0.4 amps and the battery did not pass the load test. Using Optima Red here and it only lasted 8 months. Maybe I'll try a Deka or Odyssey next time.
0.4A is still very unacceptable and no matter what battery you use will die within a week if you let it sit. My diagnostic for a stock IS300 is 0.050A, five hundredths of an amp. 0.4A mean you have an excessive amount of draw, no battery will work and is NOT the problem.

'02 IS300 MSM LSD
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post #59 of 71 (permalink) Old 03-13-2016, 12:33 AM
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Sorry I meant to write 0.4 mA
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post #60 of 71 (permalink) Old 07-25-2016, 09:02 PM
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Jason,

I just bought my daughter a '99 RX300 and while driving it tonight, I noticed the headlights would dim periodically and then come back up. I thought I heard a slight click in the passenger footwell, but I can't be sure. After a 30 minute drive home, I tested the battery and alternator best I could.
Headlights on high and AC blasting:
Engine at idle 13.52v
Bring throttle up to 2k rpm(guessing) the voltage drops to 12.6 and then comes up to 13.57v again.
Engine off, battery warm 12.75v

What do you think is happening? Faulty regulator?

Update: I bought and installed a TYC alternator from rockauto and now the voltage is spot on all the time at 14.4vDC

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Last edited by IM QUIKR; 07-28-2016 at 04:31 AM.
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