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1982 350 dual station ammeter wiring conversion

tuna_man

tuna_man

Regular Contributor
Hi Guys

Replacing 1982 engines with 1997 engines (2 x 350SBC) in a 1982 28ft bertram (flybridge).
Wish to use the 1997 engine harnesses.
Also wish to re-use the existing the original dual controls /Wiring / Gauges already fitted to Bertram.

first obstical is seems to be upstairs / downstairs ammeters. Are they in series?

wish to remove ammeters, and go with voltmeters.

engine harness socket has only 2 large pins, boat harness has 3.

It looks this is sumtin to with the two ammeters per engine.

There is a 3 way spliter harness that plugs into the engine harness, upstairs/downstairs plug into the 2 branches.

cuttin to the chase i guess im lookin for a wiring diagram for 1982 dual station, with ammeters, not voltmeters.

Hopefully I can work the rest out.
 
From what I could see,

The AMP meter hook up is (orange or red/white) and (red/purple or red). Orange or red/white being + (in) and red/purple or red - (out).

If your is the same color code then cut and tape these off well!!

Once this is done all you need to do it to replace the AMP meters with Volt meters and connect the black to ground and what ever color wire is IGNITION ON, (when the key is in the run position) this would either be PURPLE OR WHITE. Confirm with a 12 volt test light or volt meter.

No reason to be running high amperage thru your dash. Bets to go with the volt meters!!

I believe the two wire/pins in the connector on the newer wire harness is 12 volts + (RED) and 12 volts - (ground)(black)
 
Wow... good question! I'd think that two amp meters wired in series may offer an accurate reading.
However, the resistance from one may affect the other.
I'd have to give this some more thought.

If two ammeters were to be paralleled, I'd think that there would need to be a means of toggling back and forth between the two.... similar to a single fuel guage sender with two fuel guages. IOW, only one could be active at any one time.

Amp Meters are not used much these days and I doubt that your new engine/hull harness is set up for Amp Meters.

Ditto Kghost.... no real need to run this high amp circuit all the way forward and back again.... as there is no need to have the line-loss associated with this long and unnessary circuit, IMO.

Your idea of removing them and replacing them with like looking Volt Meters, is what I'd do.
You'll be abandoning a portion of the old #10ga or #8ga Amp Meter circuit.
You could leave the wires in the harness, tag them, and say goodbye!
You may find a future use for them.

As for controls, if the 1982 controls are the Morse Twin-S, it doesn't get much better than these for old school style manual cable controls.
While some may poke fun at these older controls.... the Twin-S is hard to beat and these rarely give us any trouble.
There is a Morse that looks very similar to the Twin-S, but I've had trouble with these.

I'm not quite following you on this;
There is a 3 way spliter harness that plugs into the engine harness, upstairs/downstairs plug into the 2 branches.
Click to expand...
If you are commenting on how the harnesses are joined (per engine and per station), I think that you'll find that for each engine and each station, the two harnesses are joined in a "parellel" fashion. Pretty typical back in 1982. That is how my older twin engine Sedan F/B boat is set up... as with many that I have worked on.
Example: you would be able to fire up an engine from either station, and both station instruments become powered up.... Yes/No????
And..... if you fired up from the lower station, you would be "un-able" to shut that same engine down from the Upper Station... Yes/No????
This is fairly typical.

.
 
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Thanks Rick & Ghost

Yep, I agree, 30 or 40 amps running all round the place thru old harness plugs makes no sense at all.

I estimate 40ft of unnessary high current wiring.

Yep the new engine harness does not accom ammeters, which is ok.

Yup, the controls look good, there staying.

Now, the 3 way splitter, it looks like original Merc, plugs direct into engine harness, (Y shaped, 3 ft long) has one male plug which goes to engine socket, and two flying female sockets, for low and upper helm instrument harnesses to plug into. Im after the merc diagram for this beast, so i can trace ammeter wiring functuality.

Yep, im assuming parallel operation for most of the instuments,(IG sw, oil press sw, oil press analog, temp), but not sure about the ammeters, Im assuming series as all two wire ammeters are.

However, Ammeters are 3 term, with a large Back, large Red, large Red/Wh. A small Red/Wh jumps off to supply ignition switch. All ignition wiring at dash instruments is white, on the engine ignition wiring is usual purple. If they werent 3 wire, series would make sense, but havin trouble gettin my head around havin two 3 wire (charge & discharge) ameters in the same circuit. I think Ghost is on the money with;

'The AMP meter hook up is (orange or red/white) and (red/purple or red). Orange or red/white being + (in) and red/purple or red - (out).

If your is the same color code then cut and tape these off well!!

Once this is done all you need to do it to replace the AMP meters with Volt meters and connect the black to ground and what ever color wire is IGNITION ON, (when the key is in the run position) this would either be PURPLE OR WHITE. Confirm with a 12 volt test light or volt meter".

Would like to confirm wiring as is before I start hacking...........

Any leads on a wiring diagram for 1982 dual helm?

Thanks guys.
 
From What I can see in the schematics, Pin 4 is no longer used (old amp meter feed) in current day harnesses. Pin 4 in older amp meter harnesses used pre BIA color code (red-white) wire,
BIA color code todays wire color code (orange)

Here are some pics hope this helps.
 
As to the 3-way splitter (of which is nothing more than a means of paralleling dual stations), the harness pin connector configuration is no doubt different between the hull harness and the engine harness. This may mean cutting into these and removing the Merc OEM connectors and using a good remotely mounted Marine terminal block. Blueseas may offer something that is protected.
Been there/done that with the Volvos.
Even though there is a difference in these harnesses, the color codes should be similar for the engine requirements.
I.E., temp, oil, ignition, alt field, starter motor solenoid, etc., are usaually the same color codes from model to model within a certain year range until the ABYC changed all 12 vdc Negatives to "Yellow".
Other than that..... I don't think that this will be an issue.

You mention three terminals on these ammeters! Could these be a shunt resistor style ammeter?
If so, then there is no heavy circuit forward. The lower voltage is derived from the shunt resistor data, and that data gives this style ammeter it's signal.
I've not seen the shunt style used for smaller Marine...., but never say never.

.
 
Here is some more.
I beleive the third wire is a 12 volt + junction. the alt feeds the amp meter and the 12V then goes to the KEY BAT terminal.

More schematics......
 
Thanks Ghost

printed all, now off to the boat:)

Still not sure why there is a heavy black -ve at the back of the ammeters........:confused:

Rick, they would have internal shunts, they are the standard merc, with needle centred, swing left for discharge, right for charge.
Still would like to see how they seriesed them in that splitter harness...
 
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Tunaman, the shunt style that I was refering to would be a main shunt near the engine, and then data feeds to the meter.
Like said, I have not seen this style used in small marine.
I do have experience with this style for use in heavy equipment (late 1960's) where the heavy amperage to/from an Ammeter was just not practical.
The principle is the same... it's just that the Shunt Resistor is remote from the ammeter (no heavy leads required).

You did say that you wanted to remove the ammeters and go with Volt meters.... correct?
I'd simply circumvent those circuits, and do volt meters.

.
 
Thanks boys

Worked it out, we had to remove the third large pin in the boat harness plug, then rearrange wiring at back of ammeter, as per ghosts comments.

1st attempt at this we (my mate) removed the wrong large pin, which resulted in reverse polarity at instruments and ignition switch!!!!!!!!!! ouch.

now all good. Mark.
 
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