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Jeff G.
Jeff G., Marine Mechanic
Category: Boat
Satisfied Customers: 4716
Experience:  42 years experience, Certified Master Technician, All Major Outboards, Sterndrives, Hi-Performance
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I have a Johnson 90 hp outboard 1986 serial AJ90TLCDC. There

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I have a Johnson 90 hp outboard 1986 serial AJ90TLCDC.

There is something wrong with the charge circuit as it is not charging my batery. Do you have any suggestions, is it fused? do you have any diagrams?

Diagnosing the problem will depend on whether you have a voltage regulator or just a rectifier system.
Find the small terminal strip on the side of the engine. Look for they yellow wires. Trace them back to either the regulator or the rectifier. The rectifier is a small device looks like a cylinder on a triangle and has two yellow and one red wire coming from it. #63 in the picture. The voltage regulator is #48 in the picture. Let me know which you have and I'll walk you through the service procedure.

Customer: replied 6 years ago.
Voltage Regulator system
OK you should have the 35 amp system.
First thing is to make sure the battery is fully charged.
Caution, never disconnect the battery with the engine running.
With all wires disconnected from the regulator/rectifier, using a meter set on its Diode or OHM scale, test the diodes from each of the two yellow charge wires to the Red wire.
You should get a reading one way but not the other. Check the resistance from each of the Yellow wires to case ground. You should have a high reading, typically in the M range. The Red wire should not read to ground, but may show a very high reading.
This will test the diodes in the regulator.
If there is any burning or shorting, replace the regulator.
Make sure the red wire from the regulator is clean and tight with no corrosion where it connects. This is the wire that actually carries the voltage to charge the battery.
To test the alternator coils on the stator, the coils under the flywheel, which charge the battery you will need a multimeter capable of reading peak voltage, If you have a peak reading voltmeter you can test the stator by reading between the two yellow wires from under the flywheel, you should have 17-25DVA.
Check the two yellow wires from the stator to ground. There should be no reading to ground.
Chances are the voltage regulator is at fault. But make sure all the battery connections are clean as well as the connections on the start solenoid.
If you have any further questions feel free to post back.
Customer: replied 6 years ago.

Please ignore the last message.

I have completed that test aswell and found the voltage to range between 22 and 24 V.

I did the test with the other wires disconnected and the motor running.

So i have completed all the tests, found nothing wrong. I have put another battery in and tried this it all so show's around 12.20 volts when running.

what do you suggest next?

The system works like this.
The alternator coils are in the stator. As the flywheel turns the magnets in the flywheel pass the coils generating electricity AC voltage. This voltage is sent to the regulator/rectifier where it is converted to DC voltage. It leaves the Regulator/rectifier and goes to the battery. Depending on the engine it does this usually going to the Positive terminal on the starter solonoid where the main cable from the battery to the engine is conected.
When you test the alternator coils (stator) you should get 0.17 ohm between the yellow and yellow/gray wires with them disconnected at the plug.
Here is a test for the regulator. You will need an ammeter for this. Your battery voltage must be below 12.5 volts for this test.
Connect an ammeter between the red wire from the regulator and the battery termional on the starter solonoid. Make sure you have 12V on the purple wires at the terminal strip with the key on.
Start the engine in the water under load, in gear Run the engine to 4500 rpm and check you have amperage charging about 35 amps. If not check the stator coils if they are good replace the rgulator.
Let me know what you find. This should take care of the problem.

Edited by JeffG on 1/2/2010 at 4:27 PM EST
Customer: replied 6 years ago.

I have completed those tests, and found the following.


test 1 Zero Amps

tset 2 0.7 ohms


So I assume there is a problem with the stator coils.


Can I repair these or do they need to be replaced?



OK, you are getting 0 amps from the regulator and when testing the stator yellow wires.7 ohms?
Little high, but do this.
Check the stator for any charred or dark brown (overheating) on the yellow wires. Also using the OHM meter check from each yellow wire from the stator too ground, it should be open. If grounded replace the stator. If not hold off on changing the stator. I have seen some stators slightly out of spec charge just fine.
Change the regulator. Don't try to repair, change the part. This should get you going.
If you still have a problem go ahead and change the stator. To do this you will need the proper Johnson/Evinrude flywheel puller. DO NOT use a finger type puller or anything that pulls on the teeth of the flywheel.
Once the flywheel is off the stator is a nuts and bolts job.
This should get you back on the water.
Customer: replied 6 years ago.



I made a mistake in the last message it should have read 7 ohms between the yellow and yellow and grey wires.


Can't find any charring and it is open circuit to ground

Thats out of spec however I would still replace the voltage regulator first. Usually when the stator goes bad it shorts to ground or opens so the high resistance may not necessarily cause it not to work. It would also make a difference in the manufacturer of the stator. If replacing the regulator, which is reletively easy solves the problem, that is what I would suggest.
Without a peak reading voltmeter it is harder to diagnose the stator. But since you need special tools and the cost of the stator that's why I would replace parts one step at a time.
Customer: replied 6 years ago.

Hi Jeff


I have received the regulator, but the wires look smaller and the orintation where they came out of the regulator is slightly different. The numbers on it look like


535 195 - 12BW 0A


Does this sound correct or have they sent me the wrong part



Go by the part number on the box or receipt. Depending on the vendor the wires can vary in how they come out, their outside diameter and length. Just make sure the regulator fits where the old one went, and the wires will connect properly. The regulator should look basically the same.
The numbers you gave don't mean anything to me just the original manufacturer's identification.
Customer: replied 6 years ago.

The only thing that I was concerned about was that it is the correct size ?


Do they vary in Amp's


Or if it fits it means it's a 35 amp

The regulator should have the part number 395204 There should be instructions with it that say 35amp.
Jeff G., Marine Mechanic
Category: Boat
Satisfied Customers: 4716
Experience: 42 years experience, Certified Master Technician, All Major Outboards, Sterndrives, Hi-Performance
Jeff G. and 2 other Boat Specialists are ready to help you
Customer: replied 6 years ago.
Thanks for all your help. All up and running!
Thank you allowing me to help.

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