81 Mercrusier Instrument Wiring Color code ?

Im in the process of install the gauges in the Checkmate??.Looking in the Mercrusier service manual #03 that Don posted.
Section 3 , Part-D Instrumentation. My question is ?on some of the diagrams it say?s? Pre BIA Color Code and BIA Color Code?What does the BIA mean?

Also how does an AMP meter work??When it reads 0 does that mean all is good?

Re: 81 Mercrusier Instrument Wiring Color code ?

Boating Industry of America is what it stands for.

It's a standard used in boats for wiring, specifically what the different colored wires were used for.
Pre-BIA, every manufacturer used their own color code, but they were still similar and everyone tried to stay fairly equal.

Today everyone* keeps the same color codes such as Red = 12V positive unfused, Red/purple stripe is 12V positive fused, purple is ignition, yellow/red is start/crank the engine etc.

* Everyone except Yamaha :facepalm:

Re: 81 Mercrusier Instrument Wiring Color code ?

Thanks Don.......

Re: 81 MerCruiser Instrument Wiring Color code ?

Re: 81 MerCruiser Instrument Wiring Color code ?

81 Checkmate said:

...Also how does an AMP meter work……When it reads 0 does that mean all is good?

Click to expand...

When measuring either Voltage or Current, you need to know what the correct measurement is supposed to be in order to know if it is Correct or Not.
12 is good and Zero is bad is often NOT the correct answer.

Unlike a Volt Meter that reads the Voltage Across (In Parallel with) Two points.
An AMP Meter reads the Current (Amps) Passing Between (In Series with) Two Points.

Both Meters must be able to withstand the Voltage/Current that it is measuring.
Volt Meters that go as high as 600 Volts are extremely Common.
Amp Meters that can read more than 10 Amps are nowhere near as common.

The Common Multimeter will require you to move the POS Test Lead to a separate AMP Jack to measure current.
It is Important that you understand that once you do this, the Test Leads and the Meters are essentially a piece of Wire with very minimal Resistance; Very much less than One Ohm.

If you were to place your, now AMP Meter, across the Battery Terminals, like you do when measuring Voltage,
it will attempt to measure the Current (Amp) Capability of the Battery.
The Current is likely to be in the THOUSANDS of Amps range!
Your Meter is only capable of 10 Amps, Remember!
Something is going to give. :embarassed:

Best case is the 10 Amp fuse in the meter saves the day.
Worse case is the Test Leads melt, the Meter is destroyed, and you burn your hands.

The most common use of the AMP function performed on a Boat or Auto is trying to find the source of the current drain that kills your Battery over night.

The Meter is placed in AMPs mode.
The POS Battery Cable is removed from the Battery.
The POS Meter Lead is connected to the POS Battery Post.
The NEG Meter Lead is connected to the Disconnected POS Battery Cable. (NOT the NEG Battery Terminal, Destruction will ensue!)

The Meter, Now in SERIES with the Battery, will be measuring the Battery Current (Amps).
If everything is otherwise turned OFF, The measurement will way less than one Amp.

If it is simple System, Zero might be expected.
If there are Fancy Stereos with chanel memories or clocks on-board the reading may be 0.050 to 0.100 Amps.
If the reading is a couple of Amps there is a problem.
Start unplugging things and pulling fuses until you find the source of the current.

If the reading is minimal, just for fun, turn on the bilge pump and you will see how many Amps it draws.
Try the same with the Lights, Horn, Blower, and anything else that gets your attention.
Keep in mind the 10 Amp limit of the Meter, Don't over do it.
Hitting the Engine Starter would be a very BAD Choice.

Be sure to put the Test lead back into the VOLT Jack as soon as you are done.
Forgetting to check it will make the next use the start of a bad day!

Be sure you have spare fuses for the meter before you begin.
Messing up will happen more than once before you get the hang of it.

Re: 81 Mercrusier Instrument Wiring Color code ?

One reason they stopped using ammeters is because of the long wire runs.

Alternators with a volt meter puts power to the starter solenoid terminal (~3 ft) and then to the battery through the large battery cable.
With an ammeter, all the charge goes from the alternator, to the helm (?? ft.) all the way back to the engine and the starter and then to the battery. Usually with a small wire of only 10 ga, maybe 8. As the wiring gets older and more corroded, you get less amperage back to the battery, but more heat and resistance in the long runs of wire.

Switching over from an ammeter to a voltmeter can be done, but to do it right takes some skill or you can really mess things upl.