Hope this is ok to reply to this old post....with the eng. running you should see 13-14.4 volts at the pin 3 and maybe .2 -.4v below that at pin 4...the voltage from the regulator back to the gen bulb is matched with a similar voltage from the guages behind it...If the gauge fuse is blown, the reg. pin 4 voltage goes through the gen bulb and through the gauges to ground (glows)...if the voltage from the gauges is the same as the one from the regulator..(dark)... The voltage at pin4 at "key on" s/b 5-6v...maybe the wire is grounded or shorted or loose connection at a plug...this voltage excites the field through the regulator at "crank"...If it's to low, the alternator is slow to turn on...
I just went through grief with a glowing gen light and good charge voltage at the battery... I had no idea a blown gauge fuse could be the cause...all by gauges were working as they were getting voltage backwards from the regulator pin4 wire...