Help! Nightmare Problem - Lexus Sc300 - Low Voltage - Not Rechargi

blizzil · August 6, 2010

Lexus 1995 Sc300

- Brand new Alternator

- HIDs

- Commercial Alarm System

- New Battery

I just replaced the alternator on this vehicle and yet its giving me problems - its not putting out a few volts needed to recharge the battery which after 10 minutes or so it'll just die (then need to be jumped to get going)

I switched over to the stock lights and they're a little dim.

Has anyone run into a problem with an Alternator not putting out enough volts to recharge the battery? Was it a wire or ecu issue after the fact?

This problem is driving me nuts and I would really love any advice or point in the right direction for it.

Lost and need help plz

lenore · August 6, 2010

where did you get the alternator...maybe it is defective. A good alternator should put out 13.5 to 14.5 volts while engine is running....and lights on. If not it is bad. Also are all of the battery cable connections good. Also check the ground wire for good continuity to the chassis and engine...

blizzil · August 6, 2010

where did you get the alternator...maybe it is defective. A good alternator should put out 13.5 to 14.5 volts while engine is running....and lights on. If not it is bad. Also are all of the battery cable connections good. Also check the ground wire for good continuity to the chassis and engine...

This would be the second time Ive replaced the same alternator, we took it off and tested it at Autozone and it passed all tests.

You think possibly the ground?

One mechanic has told me that those are all possibilities on top of a cellinoid (sp) short ? Im not so sure about that one

I gotta get this fixed in the next 48 hours - all advice appreciated.

blizzil · August 6, 2010

where did you get the alternator...maybe it is defective. A good alternator should put out 13.5 to 14.5 volts while engine is running....and lights on. If not it is bad. Also are all of the battery cable connections good. Also check the ground wire for good continuity to the chassis and engine...

This would be the second time Ive replaced the same alternator, we took it off and tested it at Autozone and it passed all tests.

You think possibly the ground?

One mechanic has told me that those are all possibilities on top of a cellinoid (sp) short ? Im not so sure about that one

I gotta get this fixed in the next 48 hours - all advice appreciated.

Nightmare. Just shelled out 120$ and took the alternator to autozone to swap with another -- installed it and its not *BLEEP*ing working. Im going insane - he tested the voltage and the alternators are only putting out 8-9 volts.

I'm biting the bullet and buying a whole new alternator from a different vendor (oreilly) another 140$ and hopin that'll fix the problem.

Any Suggestions here? Anything? Im shootin in the dark and this is the 2nd guy who I have had to shell out cash to that swaped the alternator with no working car :(

HELP

john_sc400 · August 10, 2010

See this page:

http://www.lextreme.com/alternator.html

Although it is entitled "How to replace Lexus LS400/SC400 alternator, it also has some good tips on how to test the charging system as well as including a simple circuit diagram.

Note in the diagram that there are two fuses shown in the regulator circuit. You may have a bad one.

FWIW, that page explains how to R and R the alternator from under the car. I was able to change the one in my 95 SC400 quite easily from the top and in less time. It was much easier and cleaner as well as faster. (The pulley that provides the tension for the serpentine belt must be removed in order to lift the alternator upwards and out of the engine compartment. One bolt holds the pulley on, but be aware that it is backwards threaded.)

Here are the steps:

Disconnect battery

Remove belt by relieving tension (14mm socket)

Remove tensioner pulley (IMPORTANT--backwards thread) (14mm socket)

Remove alternator top nut (from stud) and then lower retaining bolt (14mm socket)

Move bracket that holds transmission cooling lines out of the way

Slide alternator forward off of stud

Turn it to get access to wiring, removing both connectors. (13mm box wrench and small flat bladed screwdriver)

Lift alternator towards center of car and up, turning as necessary.

Reverse process to reinstall.

It can be done in well under an hour.

(FWIW, I'm tall and bending over and lifting at the same time [i'm also old!] was difficult so I jacked up the right side a bit to make the connections easier to reach, but I did not try to access anything from under the car)

John