Alternator charge light peculiarity/problem.

[thechuckster]

it's a british car, handcrafted by tradesmen skilled in coach-building but not that fancy electricon stuff. It's probably missing this:

[Slim]

Ian, you stay away from my wiring.

thechuckster : very funny, but the only wiring components made by lucas left in the car is the starter motor and the tail lights. Even the headlights have been replaced with Narva halogen jobbies. So your joke kinda misses the mark.

[Slim]

oldcorollas : Some of the alternator conversions that people come up with are well intentioned but so poorly executed. Did that guy with the MG really use nuts as spacers? *vommit*

This is the alternator that i was going to fit but decided on the Mitsubishi one because it was brand new and could be modified to fit without additional spacers.


Here is a discussion on Ausmini about fitting Nippon Denso alternators to minis. You should see how shit some of the brackets are.
ausmini :: View topic - daihatsu charade alternator conversion

[oldcorollas]

i was only thinking of the wiring... since you already had it fitted up...
and both those diagrams have the L and R terminals....
oh well, i tried

[Slim]

It's definitely useful info. I was more mentioning it as an aside.

[timbosaurus]

Slimbo, the L and R are supposed to be lamp and ignition respectively.

That's what i've connected in that T shaped plug at the moment. The horizontal pin of the T is ign, the vertical pin is lamp.



One lamp pin is connected to ignition and the other to the L terminal on the alternator.

That's the common way, and the way I expected it to work... but for some reason the "L" pin does not behave as expected. Will have a look at some of those links when I have a sec.

[The Witzl]

Yep....

Connect the R pin to IGN 12V+.
Connec the L pin to the charge light.
The other side of the charge light should have IGN 12V+.

Check with a multimeter.



EDIT - just read Timbo's post. It could be possible that this alternator charge light works in reverse - IE, the charge light should be EARTHED, and the other side goes to the L pin on the alternator.

The way to check that is:
- Disconnect your charge light wire from the alternator (only disconnect charge light wire)
- Turn key to IGNITION (but dont start engine). Measure the voltage on the L pin on alternator.
- Now start the engine, and measure voltage on the L pin.

.... if the voltage on the L pin is 12V when IGN is on but engine off, and L pin is zero volts when engine running.... then connect charge light to L pin and earth.
..... if the voltage on L pin is 0V when IGN on but engine off, and 12V when engine running.... then connect charge light to IGN and L pin.



Does that make sense??
Another cheating way to check is - with the way it is wired now, does the charge light illuminate when IGN is on but engine not running??

[timbosaurus]

If I remember correctly, that 'L' pin is ground 100% of the time... so the CHG lamp was on whenever ignition is on, regardless of charging or not.

Not saying it is definately wired right, but I'm wondering if it is hooked up right and there is something wrong with that output internally?

Reading one of those links says "do not short L terminal to ground while running or it can damage shit". It's always possible that I've done something like that and damaged the 'L" output while trying to see how it works. I think i'll have a look around for a new reg.

Edit: Witzl, IIRC, I don't think it simply functions back to front... I think it's gnd 100%, but Slim can confirm.

[The Witzl]

the way it should work timbo, is that with IGN 12V+ power present to the R pin on the alternator, the L pin should be 0V or 12V, depending on if the alternator is providing an output or not.
The idea is to wire up the charge light so that it illuminates only when the alternator is NOT providing an output.

Hence my little test method

[timbosaurus]

tag post, you're it

[ScreamingHeap]

OK ive checked my book and it tells me that you are correct in assuming that the L pin is the charge light. If you use a jumper wire to put the corresponding pin on your ALT harness to ground does the ALT light come on on the dash? If not its wired incorrectly. If it does light up, plug that pin only into your Alt. If the light does not come on with the key then my guess is that a diode in your rectifier is open circuit. You can also use a multi meter to test that L has continuity to ground when the motor is not running. Hope that helps.

[Slim]

With the way it's currently wired up, when the ignition is turned on but the motor is off, the light is off... When the ignition is on and the motor is running, the light is on.
Essentially... it works like the Everything's-Okay Alarm that Homer invented. It lights up when the alternator is operating properly.
‪Everything's OK alarm‬‏ - YouTube

[ScreamingHeap]

Does your ALT light come on when you ground the wire that goes to the L pin though?

[Slim]

When the car is running?

[ScreamingHeap]

No when its not running. Unplug the pug that goes into the alternator, turn the key to the on position and then get a jumper wire and put it between the chassis and the wire that goes to the L pin on that pug. Tell me if the light goes on or stays off.