1UZ alternator help

[elliotaw]

Need a little help with the wiring on my '91 1uz conversion. Ive searched the internet top to bottom and there is a lot of conflicting information and I've tried every concievable variation but I cant get my charge light to work.

On my alternator I have The main post charging wire in 4G size going direct to the battery positive via the 120 amp original fuse.

On the back of my alternator there are no markings to identify the 3 pin outlet connector and no markings on the connector plug either.

Looking at the back of my alternator there is a vertical pin on the left which goes to a slightly larger wire than the other two and is white and black. I have assumed this is the 'S' wire and I have connected that directly to the battery via the original 40 amp fuse.

The pin on the top is yellow and I assume is 'L' ???

The pin on the bottom is black and yellow. I assume that is 'IG' ???

I have wired the 'L' via a 12v LED from switched ignition position 2

I have wired the 'IG' to switched ignition position 1

My dash mounted volt meter moves from high 12's to about 14volts when the engine is started so from that I assume the alternator is charging the battery.

My charge lamp works in reverse ??? Ignition switch position 1 - nothing happens, click through to ignition position 2 and nothing happens. Continue to crank the motor and it lights up and remains lit when the engine is running.

Every car ive owned... its the other way around. Any ideas ?

Elliot

 

[Bushwhacker]

Reverse the connections on the LED?

 

[elliotaw]

I see your logic...

if I reverse it, it doesn't light up either.

If I remove the yellow wire from between the alternator and the led, and then touch the led terminal to the car body it lights up, so it's definately the right way round. Just not getting an earth signal through the alternator for some reason.

I reco'd this alternator with all new components a few years ago but it's never been run. It has a brand new (aftermarket) regulator in.. wonder if its a bad one ?

Elliot

 

[Bushwhacker]

I think the problem is the LED.
Have you tried a normal 12v bulb instead?

 

[elliotaw]

I wish it was something so simple.

I get the same result with a normal filament bulb.. even with no diode it wont light up

Elliot

 

[elliotaw]

I went to have a chat with a guy who works all day everyday with alternators and starter motors. He suggested that the "L" connection on the alternator should go via the charge lamp and then to an earth connection and NOT to a 12v supply.

That totally contradicts all the information that I have found on the forum. I'm not trying to suggest that these highly respected guys on here are wrong but I'd like to find out why there is a difference.

Anyway, I connected it as he suggested and it has fixed my problem.

I dont have the original lexus supplied schematic to prove which way this should be. Does anyone else have detail of the warning and indicator lights at the cluster ?

Elliot

 

[gloverman]

There is something strange there. Is your alternator still charging?

Is the plug the original plug from the alternator?

Looking at the plug from the back with the clip at the top(or looking into the alternator) the pins are
Top - horizontal - Sense
Bottom right vertical- Light
Bottom left vertical- IG


I buy some aftermarket plugs and their colours are around the wrong way. I dont work with colours as much as pin position.

Check the light circuit on all toyotas and bulb is supplied with ignition voltage and the alternator provides the earth until started and then the earth is no longer present once the alternator is charging so the light goes out.

If yours is working backwards something is definately strange.

 

[elliotaw]

Hi. Yes the alternator appears to be charging nicely. I see 14+ volts and my clamp meter was showing around 40 amps on fast idle with a half flat battery.

The plug is definately the original one as I cut it from the loom when I got it as a half cut.

I can confirm my pins are as you say...


I replaced the regulator when I rebuilt it. I would assume that probably came from china. Whats the possibility of the reg being internally different ?

Elliot

 

[gloverman]

Anything is possible with some of the copied parts.

I dont even bother with rebuilding most of the time now. I can get new ones at a pretty good price. And their quality is ok so far.

Strange but it works.

 

[elliotaw]

Well, it turns out the regulator was fried. Got a new one fitted into it today, got it back on the car and its working properly at last.
No idea why the dead reg was working in reverse with the indicator charge lamp, the place I bought the new reg from suggested that they can go bad if you send +12V through that wire without the indicator in line and I guess thats very possible that I did that while trying to figure out what wire was what.

Elliot

 

[Jan Venter]

The Alternator light works with your ign supplying the 12v to one side of the bulb (light) the neg is the yellow wire from the Alt. As soon as the alternator starts charging it will change the output from the yellow wire from neg to positive. The lamp will not work with two positive inputs thus the light is off. The markings is on a little plate on the side of the Alternator just look very closely and you will find it. Jan Venter