Mercathode help testing?

ProfitOfDoom

New Member
Jan 7, 2010
188
Eastlake,OH
Boat Info
1987 268 Sundancer
Engines
454 Mercruiser/Bravo Three
Can anyone make sense of this..
Mercathode System Testing
If your boat is equipped with a Mercathode system, there is a simple way to test if the system is operating properly. The goal is to check the output from the Mercathode controller. When the boat is in the water, disconnect the orange wire that comes from the anode at the mercathode controller. Set the digital reader to show milliamps. Connect the black meter lead to the terminal on the controller. Connect the red meter lead to the end of orange wire. If using the blue or black Mercathode controller, the reading should be 25 or less milliamps, to as much as 200 milliamps in saltwater areas. If using the red Mercathode controller, the readings should be less than 25 milliamps in fresh water areas to as high as 400 milliamps in saltwater areas.

So when it says connect the black tester probe to the terminal does this mean to the negative terminal? and just touch the red tester probe to the orange wire you removed to see a reading?
Also it says you have to do this in water,is there a way I can test while its just sitting on the trailer?
 
You are measuring miliamps, the red end goes to the orange wire, and the black probe goes to the terminal for the ORANGE wire. To get an amps reading you have to put the meter in line with the circuit being checked.

Yes, it has to be in the water. However, if the boat is not in the water you should also check the condition of the cathode wire on the outside of the boat. This is located on the bottom of a box mounted at the bottom of the transom ring. If you lay on your back under the drive (in trailer position) and look up at the bottom of the transom ring, you will see a bare wire running across the bottom. That needs to be clean (no paint) and not broken. If it is dirty clean it with solvent and q-tips. Sometimes these get bottom painted and then they don't work so good.

Henry
 
Can you buy replacement wires,the one came off. I crimped it back on but would feel better if I just bought new ones and put them on. Or do you just make these?
 
What wire? The little paper clip looking one on the plastic block under the outdrive? If so, you need to replace the entire reference electrode (the black box under the outdrive.) I'm going to do mine this week.
 
The ones im talking about look like think cable and has a grounding circle end so you can put a screw through and tighten it down.
 
The ground wires are available at any mercruiser service center, they come as a set for each outdrive.
 
Does anyone have a link on where to order a set? I searched and found nothing on mercathode ground wires.
 
Search for "Mercruiser Continunity Kit", the part number for a Bravo 2 kit is 99940A2.
 
Thanks,that did the trick!
Can anyone confirm if there all the same,,the model number you mentioned seems to be same for all I was able to pull up.
 
These are two different tests.
 

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