Dave P’s Regulator/Rectifier (R/R) Test for the Honda Pacific Coast PC800

Editor’s Note: I have copied this content over from the iPCRC files archive to make it easier to search and find. These directions are for testing if a regulator/rectifier (often referred to as a R/R) is good or not. The directions in the PC800 service manual sometimes do not detect a bad R/R and sometimes show a good R/R is bad. The directions here are generally more accurate.

However, when in doubt, attach a voltmeter to the bike and ride it. Watch what happens to the voltage in a variety of riding conditions. If the voltage is too high or too low, that will tell you some information about the R/R and the stator. If you suspect the stator is having issues, go check out Pogo’s test.

1. Remove the Rectifier-Regulator (R/R) from the bike.
2. Use a multi-meter with a Diode setting, any other setting will not work
3. Touch and hold the red test lead onto the positive pin on the R/R.  Using the black test lead, touch one of the 3 pins for the alternator, (A, B, C).  Write down the reading.  Do this for all 3 alternator pins
4. Move the red test lead to the negative pin on the R/R, Using the black test lead, touch one of the 3 pins for the alternator.  Write down the reading.  Do this for all 3 pins.  Just like step 3.
5. Put the black test lead on the positive pin on the R/R.  Using the red test lead, touch one of the 3 pins for the alternator.  Write down the reading.  Do this for all 3 pins.
6. Put the black lead on the negative pin on the R/R.  Using the red lead, touch one of the 3 pins for the alternator.  Write down the reading.  Do this for all 3 pins.

All readings for each step should be the same.  If something is open or way off, the R/R is probably bad.

Example readings:

Step 3: Zero   Zero   Zero    
Step 4:  532     532   531
Step 5:  526     532   538
Step 6:  Zero   Zero   Zero