Reading Ohms and Continuity etc.

[86RajunCajun]

So i am doing all my electrical tests on my outboard and i am having trouble understanding the readings i am getting.

Maybe you folks can lend me a little wisdom to help me understand and make sure i am getting the correct readings.

i am working on my 1986 mariner 150hp. Serial number is 6637210.

What i am doing is going through the troubleshooting tests in my Clymer manual and testing the Stator, coils, trigger and fast idle module.

I did what the manual said to do for the first stator test and i got the readings, but i dont know how to tell if the readings are right or not.

Test 1 says to disconnect the 2 yellow leads from the stator to the rectifier.
it then says to set the ohm meter to the rx1 scale and touch the red lead to either of the yellow wires from the stator and the black lead to a good engine ground and there should be a reading of under 1 ohm. I did that test and it was 0 ohms so I got that one I think.

The next test said to put the ohm meter on the Rx1000 setting and then the red lead from the meter on one of the yellow wires from stator and then the black lead wire on the other yellow wire from the stator and there should be "no continuity". That's where I am lost. I did the test and the meter read between 950 and 1000 ohms. Is that continuity? Getting a reading of 1000 ohms means there is resistance in the circuit?

Also, I am using a digital multimeter. A Craftsman to be exact, and the settings arent listed as Rx etc etc. For Ohms, i have settings for 20, 200, 2000, 20k. I assume if the book calls for Rx1000 that means the top range it would need to read would be 1000 ohms, and i used the 2000 setting on my mutlimeter. Should that be fine?

Thanks a lot for any information on this!

RC

 

[Silvertip]

Re: Reading Ohms and Continuity etc.

There are three basic concepts to understand when reading resistance.

Zero Ohms: This means you have zero resistance but it also means you have continuity. (More on this in a bit.)

Continuity: Means the circuit you are testing is complete. A straight piece of wire represents a circuit with zero or near zero resistance. If you measure resistance of that circuit the meter would move to zero ohms and you therefore have continuity regardless what scale you have selected. If you were to cut that wire, you no longer have continuity.

Open Circuit: Means you have "infinite resistance" and hence no continuity. Infinite means the open circuit represents so much resistance the meter can't measure it and therefore doesn't move.

Short circuit, short to ground, and a host of other terms are used but I think you get the point. Touching the meter probes together creates a short circuit so the meter reads zero (no resistance). Short to ground means the positive side of the circuit and ground are shorted together. Hope that quick lesson helps.

 

[86RajunCajun]

Re: Reading Ohms and Continuity etc.

ok, so because i got a reading of 950-1000 ohms on the test that was suppose to have "no continuity" that means that test was good because of the resistance being there, there was no continuity?

if my meter would have read 0 ohms it would have had continuity and therefore the test would have showed a bad stator, right?

thanks for the info!

RC

 

[Silvertip]

Re: Reading Ohms and Continuity etc.

Nope -- you still have it wrong. ANY resistance except infinity means you have continuity. Continuity means there is a complete circuit. The only time you DON'T have continuity is if you get no reading at all. In other words the meter doesn't move. 950 - 1000 ohms says there is resistance and there is continuity. If you are supposed to read no continuity, you are supposed to have an open circuit (infinity). Finally, when you make resistance meansurements, the device you are measuring must have nothing else connected to it. In other words you must measure it only. I think this is where your measurement is wrong. You need to disconnect the stator and then make measurement. If after doing that you still end up with continuity, the internal windings have become shorted.

 

[86RajunCajun]

Re: Reading Ohms and Continuity etc.

AH i got it. ok thatmakes it clear for me.

I got 1000 ohm resistance between the 2 yellow stator leads that connect to the rectifier when i was suppose to get no continuity. So that is one area the stator is bad.

Then i did more tests to test the connections to the switch boxes, and i was suppose to get between like 5200 and 6400 ohms and i got nothing at all. The meter never moved so that tells me the internal coils of the stator are shot then. The test said to check between the red/white and blue/white wires for the the 5200-6400 or so ohms resistance and i got nothing from them wires. The screen stayed at 1 ohm the whole time.

Also my trigger was suppose to read 700-1000 ohms between the wires i tested and it reads 1215 ohms. Again out of range as far as my manual says.

I am replacing both the trigger and the stator based on these tests.

The rectifier and coils all tested within range. I still have to test the fast idle module tho. By the time i got to it i was too drunk to fool around with any of it any more LOL.

Oh ya i also did have the stator and the trigger wires all taken off from all their mounting locations and they were just hangin there from the side of the powerhead as i was testing.

Thanks again for your help Silver.

RC.

 

[86RajunCajun]

Re: Reading Ohms and Continuity etc.

Welp, i got to lookin at the module sittin ontop my powerhead that is either a fast idle control module or a low speed/ high speed timing advance module.

Ill have to look for a S/N on the module to confirm which it is. i wanna get a spare of each of these important electrical items so that if i ever need one i have it quickly.

Ill post more info as i learn about this little project i got to fix up lol. So far fun!

Rc