Oil Pressure Gauges Only Working in Engine Rooms

[adt2]

I remember some 32Vdc boats using a DCv to DCv converter for the 12Vdc gauges. Hidden under the lower helm.

Yes, ours has a pair of 32v-to-12v converters mounted under the lower helm.

[Captain Ralph]

Yes, ours has a pair of 32v-to-12v converters mounted under the lower helm.

I would start there.

[adt2]

You know, it occurs to me that I might be chasing the wrong wire. Each gauge has two red wires on the ignition terminal - one short jumper from gauge to gauge, and one that disappears into the massive wire bundles. On my dead gauge in question, I'm getting close to 0v on both red wires.

What are the two reds on the ignition terminal for? And, in what may or may not be a related question, why wouldn't they run a single cable to a terminal block and then run smaller cables to each gauge, instead of running a thousand cables all the way to wherever they're going?

[Captain Ralph]

You know, it occurs to me that I might be chasing the wrong wire. Each gauge has two red wires on the ignition terminal - one short jumper from gauge to gauge, and one that disappears into the massive wire bundles. On my dead gauge in question, I'm getting close to 0v on both red wires.

What are the two reds on the ignition terminal for? And, in what may or may not be a related question, why wouldn't they run a single cable to a terminal block and then run smaller cables to each gauge, instead of running a thousand cables all the way to wherever they're going?

Usually blue, but I guess it could be red; Back light..

[adt2]

Actually I think the backlights are on a separate terminal. Those actually are one hot wire that gets split right at the helm and run to each gauge.

[Captain Ralph]

With out the prints for your boat in front of me, I am still guessing at this.
Find the DCv to DCv converters and check in / out voltage.
Some converters have a fuse, others have a remote fuse.

I remember talking to a NewMar rep many years ago. Hatterass special ordered a large run of converters with out a switch. Replacement converters units may have a switch. Somethings to check.

Back at that key switch, No DCv out? In?

[adt2]

With out the prints for your boat in front of me, I am still guessing at this.
Find the DCv to DCv converters and check in / out voltage.
Some converters have a fuse, others have a remote fuse.

I remember talking to a NewMar rep many years ago. Hatterass special ordered a large run of converters with out a switch. Replacement converters units may have a switch. Somethings to check.

Back at that key switch, No DCv out? In?

1. I have the prints...what am I looking for?
2. I'll check the converters, but I would be surprised if they're to blame:
2a. Nothing else doesn't work - surely there's not a converter dedicated to a single gauge?
2b. I've traced the long red wire to the bottom of the helm (doesn't sound like much but it took all day and about 100 cut wire ties) and it looks like it almost certainly goes with the bundle of wires to the starboard engine room (across the top of the helm to the port side, down the front of the helm to the deck, across the deck to the starboard side and down through a hole in the floor).
3. Given #2, I'm not sure the fuse/no-fuse issue would be related.
4. Ditto #3
5. I haven't checked the key switch, but I assume I'm getting DCv out if it's supposed to be there - all the other gauges on the starboard side come to life when the key is turned on.

Thanks for your help.

[adt2]

I am still trying to solve this problem. I am currently tracing the wire from the back of the gauge into the engine room, looking for breaks or loose connections. Can someone explain to me where the wire from the sender goes? Does it go from the sender directly to the gauge? Or does it get terminated somewhere else and then routed to the gauge?