Here are a few answers to the comments: All of this started with replacement of old switches for new ones. Same wires but each terminal cleaned before attachment. I find it hard to believe that cleaned terminals and new switches caused a ground fault problem at some remote site that was not there before. Things were generally working before I did anything. Now nothing works. To Dwights suggestion: After reading that Marine How to article years ago, I replaced all the trailer connectors with heat shrink direct butt splice connectors for each wire. I also installed a Blue Seas ACR/battery switch, so the batteries are supposed to be isolated.
I really can’t understand how this problem is affecting both batteries when the two circuits are isolated by the ACR. When I try to start the engine, everything goes crazy- including both battery volt meter readings. The meter goes completely blank as if both batteries are dead and then voltage slowly recovers over time. I am also mystified by how I can be measuring over 12V on the plus side of the key switch and 10V on the other side when it is on. That is measured relative to a ground terminal on the tachometer. There is nothing there except the switch itself, right? I am guessing that means something in terms of the problem, but I don’t know what. Thanks- Dave S/V Aries 1990 C&C 34+ New London, CT > On Oct 26, 2022, at 11:48 AM, dwight veinot via CnC-List > <cnc-list@cnc-list.com> wrote: > > If you have a Universal M4-30 engine with associated engine control panel > with ammeter this article contains some very important information for you to > know. > Universal Diesel Engine - Wiring Harness Upgrade - Marine How To > <https://marinehowto.com/universal-diesel-engine-wiring-harness-upgrade/> > Dwight Veinot > C&C 35 MKII, Alianna > Head of St. Margaret's Bay, NS > d.ve...@bellaliant.net <mailto:d.ve...@bellaliant.net> > > > > On Tue, Oct 25, 2022 at 11:10 PM David Knecht via CnC-List > <cnc-list@cnc-list.com <mailto:cnc-list@cnc-list.com>> wrote: > More diagnosis- I found that when I checked the voltage at the engine panel > ammeter (where power comes to the panel), it was 12V. When I checked at the > input side of the key switch it was 12 V. When I turned the key switch on, I > got 10V on the other pole of the key switch and everywhere downstream. I am > presuming it should be 12V on both sides. I do not understand what that means > and hoping someone else does. The other weird thing is that as I have worked > on this, there are times when the battery meter in the cabin bounces all over > the place from 9V to 12V and back and then finally settles at 12.9V. At the > same time, the batteries are measuring 12.5V. Something very strange is > happening. Dave > > S/V Aries > 1990 C&C 34+ > New London, CT > > <pastedGraphic.tiff> > >> On Oct 25, 2022, at 2:56 PM, David Knecht via CnC-List >> <cnc-list@cnc-list.com <mailto:cnc-list@cnc-list.com>> wrote: >> >> HELP! I am stumped and hoping someone can point me in the right direction. >> Long descrition as best i can recall. Two weeks ago i thought i would get a >> head start on a project. My start button has been flakey this summer with >> now and then nothing happening when pressed. Decided to replace key switch, >> glow plug and start buttons. I installed key and glow but could not get >> start out so gave up. Engine started fine after rewiring. Come back next >> week and no response to start button. Battery fine. Lots of messing around >> but no luck. Come back today and wire in new start button in case old bad. >> Recheck wiring and realize key switch is wired backwards (does it matter? I >> guess you are supplying power to downstream stuff when off?). Did not check >> and misremembered which wire supplied power. Swapped wires on key switch and >> checked meter and 12v on proper side (bat).All looks good. Turn on key >> switch and fuel pump starts as normal. Push start button and nothing. Now i >> measure 4v at engine panel instead of 12. Battery meters dead display and >> measuring 4v at its inputs. But 12v at battery and main power switch. Other >> devices fine. Over an hour now and panel and battery meter up to 6v so seems >> to be slowly recovering. What is going on? Did i screw something up when key >> switch was backwards? Dave >> >> Sent from my iPhone >
