Alternator D+ / 61 Terminal

[PaulRainbow]

Update.
Connected wire with in line 10 watt 39 ohm resistor between starter battery and the D+ terminal on the alternator. Voltage on the D+ terminal was 4.88V.

Started engine, left at idle, and alternator working fine.
So can safely say that this set up allows my alternator to work.

This was just a temporary solution. A planned permanent solution is to use a normally open relay to connect battery voltage to D+ via the resistor. Relay will be energised by the 12V to the starter motor solenoid.

That's pointless, just add more points of failure. Also means the wire is live anytime the isolator switch is on.

About 4 hours after removing the temporary wire and resistor I restarted the engine, and again the alternator kicked in and was working OK.

That'll just be residual magnetism.

At the moment, I'm still using the borrowed new style alarm/light module (with the LED bulbs).
I'll check again next week on next visit to the boat. If the alternator kicks in we'll call it case closed. If not, will fit the relay as shown in the diagram.

Just connect the wire with the resistor to d+ and the same terminal on the key switch as the warning lamp. That way it's only live when the key is on. Job done.