VWDiesel.net The IDI, TDI, and mTDI source.

General Information => General => Topic started by: wdkingery on January 24, 2013, 01:00:42 pm

Title: alt light backwards
Post by: wdkingery on January 24, 2013, 01:00:42 pm
My alternator fell apart, and during its final demise, the alt light got to doing strange things. After I installed a new alternator, the light is on dimly at idle, and gets brighter as rpms climb. 13.8v at the b+, 13.3v at the positive terminal on the battery..?

Thoughts?
Title: Re: alt light backwards
Post by: RabbitJockey on January 24, 2013, 01:27:51 pm
mine did this when i had a bad voltage regulator, it would also stop charging at the same time and the tach would do funky stuff.  that led basically has 12v going to it all the time.  when the alternator isn't turning then the - side of the led gets grounded through one of the 3 windings in the alternator.  When the alternator is charging, there is 12v going to the - side of the led and 12v going to the positive side of the led so it doesn't light up because it has positive and equal voltage on both sides of the led   id thoroughly check that alternator out, or take it to get tested fromw here ever you bought it.  mine that did that was from autozone.