Well, heh. No it wasn't. easy. I don't "do" phacePhlant and in any case the link does not work.
70. No diode should be added, the idea is to figure out what is wrong with it
You have a voltmeter? Make some simple tests.
FIRST Check grounds or better, replace and add some. You need a good ground from the battery to the block which runs the starter. This is the largest cable. Additionally, the body should be bonded to the battery neg. This is often a jumper from the main neg. post clamp to the fender, and is NOT adequate
Put larger grounds from block to body if there are none.
Then, dismount the regulator, clean the firewall and VR mounting flange and remount TIGHT with star lock washers.
Now, make some voltage checks
Identify your ignition 12V source voltage which is going to depend on the type of ignition. With a 4 terminal ballast resistor this is a bit more difficult. You want the 12V switched wire "from the key." One you can for sure use is the blue field wire on the battery. Measure this with key in "run" but engine stopped. This should be within .3V of the battery. That's 3 tenths of one volt.
Now, check ground. Run engine at good fast idle. Put one probe on the battery neg. post, and the other stab into the mounting flange of the voltage regulator. Once more, you are hoping for LESS than .3V
Another thing you can try, is make a means (using flat spade "push on connectors") to "tee" into the blue field wire connection. With the car running, jumper this connection to the battery. See if the pulsing stops
If none of the above fixes it, try a different regulator.
