Alternator problem, help needed...

[C-NUMB]

Not rib but marine engine related...would highly appreciate if anyone here that knows alternators would give a helping advice? Long story but during tracing a ground leak found that the voltage sense terminal on the alternator side grounds somewhat.

The red white wire(red arrow) goes to the terminal that i worried about, the purple is ignition.

As its a + voltage terminal seams strange to me, Is that OK or not? Then checked with a multi-meter(between that terminal and ground), with the setting on 200K got a reading of 40 (ohm?). Maybe perfectly normal but would have taught that as its a + voltage terminal should be fully isolated from ground?

If this is not right, any guesses what might cause this, is it possible the rectifier diodes that are killed or voltage regulator maybe?

Thanks for any input!

[beamishken]

Originally Posted by C-NUMB

Not rib but marine engine related...would highly appreciate if anyone here that knows alternators would give a helping advice? Long story but during tracing a ground leak found that the voltage sense terminal on the alternator side grounds somewhat.

The red white wire(red arrow) goes to the terminal that i worried about, the purple is ignition.

As its a + voltage terminal seams strange to me, Is that OK or not? Then checked with a multi-meter(between that terminal and ground), with the setting on 200K got a reading of 40 (ohm?). Maybe perfectly normal but would have taught that as its a + voltage terminal should be fully isolated from ground?

If this is not right, any guesses what might cause this, is it possible the rectifier diodes that are killed or voltage regulator maybe?

Thanks for any input!

Assuming thats the wire connected to the ignition light it is ground when not charging & illuminates the charge light. Once the alternator starts charging it becomes positive & extinguishes the light however there should only be power to the light when ignition is on

[C-NUMB]

Originally Posted by beamishken

Assuming thats the wire connected to the ignition light it is ground when not charging & illuminates the charge light. Once the alternator starts charging it becomes positive & extinguishes the light however there should only be power to the light when ignition is on

No ignition light in this /system. Consider the alternator to be on the bench, nothing connected, not moving. When measuring, the voltage sense terminal is not isolated from negative/ground (ohm readings as above).

[beamishken]

What I'm saying is the ignition light terminal will go to ground when not charging

[C-NUMB]

OK, noted thanks. Here a wiring diagram, the possible problem is marked with red, the "SEN" terminal. Not an electrician(probably clear for all at this stage ) but it looks like there is a direct line from battery positive to that terminal, no switch between. So don't get it if engine is not running why positive should be grounded for this specific alternator?

[C-NUMB]

Have been trying to search the web a lot.... Only thing that found was that this voltage sense terminal is sometimes jumped directly to the + on the alternator, the sense function is to give signal to voltage regulator. Seams unlikely that it should be grounded?

So the question would then be, is the rectifier with diodes killed or voltage regulator ?