Yanmar 1GM10 Alternator Relay

[Potato Head]

I have a 1GM10 in my yacht and the alternator is not giving out charge. Had an auto electrician check it out and all is ok. The problem appears to be with a relay between the wires that come out of the alternator and go to the charge light. The two wires come out of the alternator and pass through a six pin relay. From here a +ve and -ve wire go to a set of terminals that aren't connected to anything. One -ve wire is on its own and is connected to nothing. The other two +ve wires and one -ve wire then go to a plug which is connected (via a +ve and -ve wire) to the charge light. When I bypass the relay the alternator charges without issue (13.8 V).

Does anyone know if I am damaging anything by doing away with the relay? It doesn't appear to be there for anything on this boat (a Mumm 30) - perhaps its for other installations?

Thanks guys

 

[prv]

I don't remember a relay in the standard wiring diagram, so presumably this is someone's modification for a charging system, or automatic steaming light, or similar. I'd remove it, and reinstate the loom to what's published in the workshop manual (available online but I don't have a link).

Pete

 

[VicS]

As Pete says there is no relay as original equipment associated with the alternator and I think I'd feel inclined to do what he suggests

What it might be is a charge control relay for contolling the charging of a second battery.

These are energised by being connected to the warning light terminal and close to connect the second battery to the alternator once the volts at that terminal rises.

However I cannot rationalise your description of the wiring with that.

You'll find wiring diagrams for the engine in the workshop manual that you can down load from http://www.motoren.ath.cx/

You might be able to identify the relay from any numbers etc on it.

 

[davidwf]

I seem to recall that the 1GM10 has a relay to disconnect the alternator to reduce the load as the engine starts.

 

[prv]

I seem to recall that the 1GM10 has a relay to disconnect the alternator to reduce the load as the engine starts.

If so, Yanmar didn't bother to put it on any of the three relevant diagrams in the workshop manual, or to mention it in the text.

Doesn't rule out it being a common field modification, I guess, if 1GMs are routinely strangled by their alternators.

Pete

 

[oilyrag]

There is an inline fuse in the 1GM10 wiring harness - not obvious unless you know it's there but maybe worth checking..

 

[Rattler]

I have a 1GM10 in my yacht and the alternator is not giving out charge. Had an auto electrician check it out and all is ok. The problem appears to be with a relay between the wires that come out of the alternator and go to the charge light. The two wires come out of the alternator and pass through a six pin relay. From here a +ve and -ve wire go to a set of terminals that aren't connected to anything. One -ve wire is on its own and is connected to nothing. The other two +ve wires and one -ve wire then go to a plug which is connected (via a +ve and -ve wire) to the charge light. When I bypass the relay the alternator charges without issue (13.8 V).

Does anyone know if I am damaging anything by doing away with the relay? It doesn't appear to be there for anything on this boat (a Mumm 30) - perhaps its for other installations?

Thanks guys

I had a Mumm 30 which had problems with starting due to the load of the saildrive and the alternator. When the drive belt was removed the engine started with no problems. There is a modification to cut out the alternator when starting and after the engine starts drop in the alternator to and start charging.

This a a known problem with the 1GM Yanmar with a saildrive.

 

[Tammany]

Their is definitely no relay in the wiring of the Yanmar 1GM10 as deconstructed mine at the weekend. The charge lamp connects directly to the small plug in the rear of the alternator. Blue/black at alternator through to blue black at lamp the red/black to white/red in extension cable back to red/black to alternator plug. I suspect the relay has been added as some point to power something that only runs when the engine is on. Cooler maybe??