Hi,

My 'amp' light came on while driving - sporadically at first, and then permanently. Fan belt tension and fuse # 1 are fine - no corrosion in the fuseholder. With the engine running there is 12V at the regulator B+ terminal and no reading at the D+ terminal. I swapped the dynamo (generator) with a newly reconditioned one - no improvement. I fitted a new regulator - no improvement. Both parts were supplied by an Amazon specialist so I'm assuming that they're right. Now I'm stumped. After I fitted the dynamo, I polarised it by flashing a wire between the DF terminal on the dynamo and the battery positive terminal (the dynamo was still connected to the regulator) - now I'm wondering if it makes any difference
a) if the dynamo is connected to the regulator when this is done?
b) if the engine should be running or not? (it wasn't)
b) if the lead should be connected to the battery first and then the dynamo or vice-versa? (or does it make any difference at all?...)
c) if a thin lead is sufficient? - it was thin cable (like speaker wire)

Anyone have any thoughts on the above? Can anyone tell me how I can check the dynamo and regulator for output with a voltmeter - the Haynes manual is vague as to what cable goes where for testing and I'm not an electrical expert (as you may now have gathered...) I would have assumed that the dynamo D+ terminal would give some sort of output but it doesn't.

Any help would be very much appreciated

Aidan