Technical Articles


Trouble shoot your generator/regulator

Light on dash!! Could be a broken fan belt, or it could be the brushes in the generator need to be replaced, or...
Here are some trouble shooting tips to help keep you going.
First, buy some kind of a volt meter. I have one in my carry along tool kit that I picked up at a flea market for $8.00. I've used it a number of times and it has more than paid for itself. (Remember, the shops cost a minimum of $40 per hour.)

2. You need a couple of pieces of wire, preferably with clip leads on the end. You can pick them up from Radio Shack.

3. OK, now you want to determine if the generator is good. do this:

   a. Stop the engine.
   b. Remove the DF lead from the generator.
   c. Connect the + side of your volt meter to the D+ terminal on
      the generator, and the - side to a good chassis ground.
   d. Be sure all the wires and tools are clear of the fan belt
      and start the engine.
   e. Connect one end of a jumper lead to the DF terminal on
      the generator.  While revving up the engine (just a little)
      with your left hand, touch the free end of the jumper to
      chassis ground.  The volt meter should indicate somewhere
      between 13 and 18 volts.

(NOTE: This is what the regulator does. It senses a low voltage condition and connects the DF terminal to ground. Now you know)

   f. If the meter doesn't indicate the voltage, check the
      brushes.  You should carry a spare set in your portable
      tool box.  Just swap them out and run the test again.
   g. If the meter does indicate the proper voltage, the regulator
      is probably bad.  Not much to do here except swap it out.

Polarize the generator

You should do this anytime you replace a generator, or you can do it in place of the above to test the generator.

   a. Stop the engine.
   b. REMOVE THE FAN BELT. (You can burn out the generator if
      you don't)
   c. Remove D+ and DF wires from generator.
   d. Connect the DF lead on the generator to chassis/battery
      ground.
   e. Use a jumper wire to connect battery + to the D+ side of
      the generator.  Just connect it temporarily.
   f. The generator should start to turn, like a motor.
      If it does, the generator is probably good, and it is now
      properly polarized.

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