Alternator Problems? Get Fast Repair! (28-08-2002, 21:53)

Hello,

I drive a second-generation Golf TD, and I'm having a problem: the charging light never comes on, even when I just turn the ignition on. When I use a different alternator, it works correctly, so the diode isn't faulty.
However, I didn't want to give up the old alternator because it has the W terminal for the tachometer, which the other one doesn't.
Okay, my question is: Is there anything that can be done about this part, or not? I would like to be notified if the LM (likely referring to a light module or similar) stops working.
Thank you in advance for your tips!

Hi.

Perhaps replacing the regulator would help, especially if those thin wires are connected to it.

Hi,

Okay, let's do a test with a voltmeter on the battery. The alternator is "pre-excited" via the charging indicator light or LED. If this pre-excitation is missing (I can't recall the terminal designation at the moment, but you can find it in a wiring diagram you trust), then the charging voltage at idle will not be significantly higher than the battery voltage when the engine is not running. Only when a certain engine speed is reached will you get the full onboard voltage (until the next time the engine is turned off).
I once had a similar LIMA problem, but in that case, the wiring to that terminal was faulty, not the LIMA itself.
I can easily imagine that this could also happen within the LIMA system. So, if replacing the controller doesn't help, then you need to open it up and take a look inside.

Olli.