Diagnosis Confirmation

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98 Lexus 400 305K.

2 month old 84 month Lexus battery
New Lexus Serpentine belt
Original Alternator

Battery light and Headlight leveling warning lights came on instrument cluster

Checked headlights and they move up and down on startup. Headlight leveling working ok.

Battery 12.6 volts with car off
CCA rated at 630 but reading 720
Battery voltage at 13.6 with engine running and nothing on
Battery voltage 12.9 with engine running and lights, radio and heated seats on. Engine RPM's decrease as well.

My diagnosis is a new alternator.

What is your opinion? 21 years is a long time for a radiator.

New OEM Lexus Alternator $250
 
Originally Posted by benjy
many autoparts stores will check + load test for FREE!!

Originally Posted by benjy
many autoparts stores will check + load test for FREE!!


This, get the test done but then go for an OEM or rebuilt if you intend to keep it.
 
I replaced the alternator on my 93 LS at about 300k also.

It failed due to a power steering leak at the pump, which is located directly above the alternator.

I know this is not your current issue... but if you determine a replacement alternator is necessary, you may want to make sure the power steering pump is good too.
 
The voltage looks OK. I would expect some drop at idle with all the accessories on. Test at 1500 rpm instead.

But the "battery" light is controlled by the regulator inside the alternator so light coming on while the alternator is powered up and spinning almost always means bad alternator.
 
Originally Posted by CELICA_XX
I replaced the alternator on my 93 LS at about 300k also.

It failed due to a power steering leak at the pump, which is located directly above the alternator.

I know this is not your current issue... but if you determine a replacement alternator is necessary, you may want to make sure the power steering pump is good too.


Thank you!
 
Originally Posted by mk378
The voltage looks OK. I would expect some drop at idle with all the accessories on. Test at 1500 rpm instead.

But the "battery" light is controlled by the regulator inside the alternator so light coming on while the alternator is powered up and spinning almost always means bad alternator.


Thanks.
 
Originally Posted by Donald
Any rebuild shops around? Rebuild of the factory alternator is always my first choice.


Not around here. I feel the Lexus OEM for $250 is a great deal.
 
Battery voltage is always low at idle, comes up once you're driving. As others said, go to an auto parts store and get the system load tested and they'll tell you how bad it is.

I guess $250 isn't bad, my Mercedes alternator, a rebuilt Bosch was under $200 at Autozone when using a coupon code.
 
I'm embarrassed to go to an auto parts store and have them check it and then go somewhere else and buy an alternator.

I just can't do it. What's wrong with me? It makes me feel like I'm 18 again and telling a girl I love her just to get 20 minutes of her affection.

I realize I may have some deep psychological issues from my childhood but....
 
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Originally Posted by Gebo
Originally Posted by Donald
Any rebuild shops around? Rebuild of the factory alternator is always my first choice.


Not around here. I feel the Lexus OEM for $250 is a great deal.

Yeah, why spend $100 on junk ?
 
Originally Posted by Mr Nice
Originally Posted by Gebo
Originally Posted by Donald
Any rebuild shops around? Rebuild of the factory alternator is always my first choice.


Not around here. I feel the Lexus OEM for $250 is a great deal.

Yeah, why spend $100 on junk ?



I'm sorry. I don't understand. Are you agreeing with me or disagreeing with me?

I think you are agreeing with me.
 
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I would agree with you, unless you have a rebuilder you trust enough to fix it correctly. We're running out of rebuilders around here.
frown.gif
 
I don't trust those part store test benches.

On any Lexus or Toyota with a UZ-series V8, the PSP is mounted above the alternator. If the pump leaks(the most common places is the idle-up valve, the pressure fitting and the pick-up elbow/reservoir O-ring), it will spill fluid on the alt and take out the brushes and slip rings. The pump itself isn't hard to reseal - it's a $40-50 kit from Toyota and takes a few hours.

OEM or Denso reman is my choice for these.
 
Originally Posted by nthach
I don't trust those part store test benches.

On any Lexus or Toyota with a UZ-series V8, the PSP is mounted above the alternator. If the pump leaks(the most common places is the idle-up valve, the pressure fitting and the pick-up elbow/reservoir O-ring), it will spill fluid on the alt and take out the brushes and slip rings. The pump itself isn't hard to reseal - it's a $40-50 kit from Toyota and takes a few hours.

OEM or Denso reman is my choice for these.


Just checking out prices other than dealer. Parts geek had 2 Denso alternators. Different prices. OEM from dealer is reman Denso. I asked parts mgr if all reman Denso are the same and he said he suspected some reman Denso are not done with OEM parts. Interesting 🤔
 
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Agree first step is to check the power steering pump so OP doesn't toast the replacement alternator. After that $250 for a OEM alternator on a car you still enjoy and which was built like the oldschool LS seems worth the cost to me.
 
Originally Posted by Gebo
Originally Posted by nthach
I don't trust those part store test benches.

On any Lexus or Toyota with a UZ-series V8, the PSP is mounted above the alternator. If the pump leaks(the most common places is the idle-up valve, the pressure fitting and the pick-up elbow/reservoir O-ring), it will spill fluid on the alt and take out the brushes and slip rings. The pump itself isn't hard to reseal - it's a $40-50 kit from Toyota and takes a few hours.

OEM or Denso reman is my choice for these.


Just checking out prices other than dealer. Parts geek had 2 Denso alternators. Different prices. OEM from dealer is reman Denso. I asked parts mgr if all reman Denso are the same and he said he suspected some reman Denso are not done with OEM parts. Interesting 🤔


I was thinking the same thing. Just because the housing on a rebuilt says Denso doesn't mean the innards are Denso. Good luck with it.
 
Originally Posted by Donald
Any rebuild shops around? Rebuild of the factory alternator is always my first choice.

THIS! An old line generator/alternator shop will give you a better quality rebuild than a parts store China/Mexico rebuilt swap. And you get your original alternator back.
 
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