We have an ancient but brilliant Micra K11 which will be 25 next year. I put four new tyres on it a couple of weeks ago and then last week the very old battery died so I replaced that too. Now find the new battery is going flat overnight and realise I have a significant parasitic drain. Have pulled every fuse with the meter in circuit on the neg battery terminal and none stopped the discharge, have checked every relay bar one, which is up under the dash and which I just cannot get out, with same result. The pos battery clamp has two cables plugged into it which both stop the drain when pulled. When I did a continuity check between the battery end of the cables and the alternator terminal where the main cable into the alternator is bolted, both made a circuit. Now suspecting I have an alternator diode failure so want to check for a circuit across the alternator terminal and case, in both directions, to see if I get a circuit in one direction only, both directions will confirm diode failure.
So, first question. My multimeter is as old as me and has no position for testing diodes as modern meters do. Normally I use ohms / resistance for circuit testing but I'm not sure which end of the scale to set it, presumably the minimum but guidance appreciated.
Second question. The two cables that plug into the pos battery clamp vanish into the wiring loom so I can't tell if they do go direct to the alternator or if they connect to something else which might be the culprit. Can anybody confirm that these are both alternator feeds and likely to run direct.
Any other thoughts and suggestions would be much appreciated!
Thanks in anticipation.