“L” Light Gremlins!

[xderbyx]

I was able to use the factory ground and put it to a timing chain cover bolt (figured it might be more direct) but even with that added, I’m still glowing big and bright “L”!

 

is there anything else tied in with the charging system? I’m feeling like my issue isn’t a ground. Idk why but I’m feeling like the “bad diode” suggestion makes a lot of sense. But I’m sure some of you guys know way more about these particulars in this car than I do!

[Chris_B]

Have you checked the voltage at your battery, with and without your motor running? I presume  you have a voltmeter...

 

You should be seeing +12.6V at the battery with the motor not running and + 13.4 with the motor running (make sure to blip the throttle after starting to make sure the alt kicks in).

[John76]

If all the above does not solve the problem, then test for bad diodes.

[xderbyx]

7 hours ago, Chris_B said:

Have you checked the voltage at your battery, with and without your motor running? I presume  you have a voltmeter...

 

You should be seeing +12.6V at the battery with the motor not running and + 13.4 with the motor running (make sure to blip the throttle after starting to make sure the alt kicks in).

I’ve been checking voltage pretty religiously in case there are any changes or improvements with all of this troubleshooting. It was around these marks but the alternator was only getting upper 13’s/14 with some throttle. 

7 hours ago, John76 said:

If all the above does not solve the problem, then test for bad diodes.

I think this is next step for sure.. I meant to ask earlier if there was a way to test the diodes, which now I’m figuring there is! What’s the best way to do this?

[AustrianVespaGuy]

It's almost for sure the diodes, as the non-alternator side of the light is fed by 12v switched by the ignition.  So if it were the ignition switch side, you'd very likely have something 'else' that's obviously not turning off correctly as well.

Test is pretty simple.  You'll want to disconnect the big red wire going from the battery to the alternator, but still leave the battery connected to the rest of the cars electrical system.  If the light then goes off, as I expect it will, then you'll know that your errant 12v is coming from the battery and *through* the alternator, instead of being 'stopped' by the alternator diodes.

Though I suggest disconnecting the battery negative before you go to undo the positive wire from the alternator, and then only replace it once you have that lose wire safely isolated and impossible for it to touch any part of the engine/chassis before reconnecting the negative side.  Safety first!

Edited September 30, 2021 by AustrianVespaGuy

[John76]

I seem to recall another test, while the BIG RED is disconnected.

Put one lead of your multimeter (set to Ohms) to the B+ terminal and the other lead to the alternator body.

Should read either Ohms or Open. Reverse the leads and check again.  Should be one of each reading, but not 2 Ohms or 2 Opens.

This checks that the diodes are working in only one direction.

[Chris_B]

It seems to me that this focus on whether one or more of the diodes are defective is a bit of a waste of time. Replacing the diodes is not a job for the average shade tree or home garage mechanic (I count myself among that group). Pick up a reman, recycled or new alt. Install it. Job well done. They really are really hugely inexpensive considering the importance for vehicle function and reliability. And, you can likely do an upgrade to a far more powerful alt. for less than the cost of a reman (new) original 02 alt. For example, I am running a 90 Amp alt. from an E30 in my 02. Easy conversion.

[AustrianVespaGuy]

10 hours ago, Chris_B said:

It seems to me that this focus on whether one or more of the diodes are defective is a bit of a waste of time.

Well, not really, because this quick/free test would at least tell us for SURE that the fault IS with the alternator itself, and not somewhere else in the car's electrical system.  Would suck to replace a perfectly good alternator and then still have the same problem, wouldn't it? I'm already 95% sure the alternator is the fault, but that final 5% confidence comes at an awfully cheap price.

I too do prefer upgraded/internally regulated alternators when doing a replacement though!

[Chris_B]

Sorry, I thought the alt test had already been done.