Charging woes!! - Troubleshooting - VWDiesel.net The IDI, TDI, and mTDI source.

• Charging woes!! by Hammy on 04 May, 2009 19:25
• I have a '91 Golf, 1.6, with the 'W' connection. I'm having a problem with it charging. Sometimes it does, sometimes not. I can tell if it is not charging, as the tach stops working, then I check it with a multimeter. I can get it to charge if I apply power to the field.
  
   What controls the field excitation?
  
  Thanks;
  Hammy
• #1 by Vincent Waldon on 04 May, 2009 19:39
• D+ terminal at the alternator via a blue wire to the "BAT" LED on the cluster.
  
  Very interesting problem. ;-)
  
  Are you getting a consistent "BAT" light when you turn the car to "ON" ?  Does the "BAT" light come on when the tach stops?
• #2 by camboscams on 04 May, 2009 19:59
• Not to thread jack, but while were on the subject... My batt light stays on all the time. No tach in car, just clock. No "w" connecter
• #3 by Hammy on 05 May, 2009 18:43
• Thanks for the reply Vincent. As for the battery led, (I just noticed) it doesn't come on at all. Is there a relay in the car that excites the field?
  
  Thanks;
  Hammy
   :?
• #4 by Vincent Waldon on 05 May, 2009 19:16
• Nope, the alternator is excited simply by current flow thru the dash LED.  No LED, no excitation is taking place.
  
  After checking for the obvious things, specifically a loose blue wire at the alternator, you can isolate the issue by removing the blue wire from the alternator and grounding it.  The BAT LED should now come on when you turn the key to the ON position.  
  
  If it doesn't, there's a problem upstream... the wiring to the cluster or the cluster itself.  Since it's a LED it rarely burns out... connection issues are more likely.
  
  If it does, the problem is downstream... ie the alternator itself.
  
  BTW, the voltage regulator is internal and so you don't actually have access to the field windings; at least not without surgery.   If you've been supplying voltage to the blue wire and getting it to charge you've been exciting your alternator manually. :wink:
  
  
• #5 by Hammy on 05 May, 2009 20:09
• Thanks again Vincent. I'll give that a once over tomorrow.
  
  Jas
• #6 by Hammy on 24 May, 2009 12:49
• 
   Ok, it's been awhile! LOL! Anyways, I still don't get a battery led light on the dash. But, I installed a new alternator, and my charging problem appears to be fixed. Now I tried grounding the blue wire, still no light. I wonder if it could be the led, maybe it's in parallel with the circuit, therefore the field still gets excited. I had power on it it once the alternator started charging, so it must be the led, or something in the cluster itself?
  
  Thanks;
  Jas