alternator or diode board or what?

[GrimReaper]

I talk with Rick again this morning and he suggest to buy a new multimeter.What a surprise  :othe new one shows 3.7 ohms.I guess my multimeter and my vdo gauge get broken in the same time.
  Thank you for your help guys

[Bob_Roller]

I had that problem, chasing a hard starting problem with my '81 R65, the meter I had, showed the proper resistance for the ignition coil, 1.5 ohms .

It was suggested that I get a known good meter to check out the coil .

I brought the coil to work, and checked it with a calibrated Fluke meter, and found the coil to have about a third of the resistance it should have .  

Troubleshooting can get tough, when your test equipment isn't right !!!!!!