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Author Topic:   Tachometer: 1999 Johnson 70-HP two-stroke
David C posted 10-07-2006 04:21 PM ET (US)   Profile for David C   Send Email to David C  
I just had the motor changed on my boat. My tachmeter did not work after the new motor was installed. I asked the mechanic about it and he said "bad tachometer." I replaced the tachometer and still have the same problem. The settings are correct on the tachometer. It lights up, goes to 0 when the key is turned on. Both tachometers are the same brand, Teleflex red international. The mechanic told me to connect the gray wire to the "S" [SENSOR terminal] on the back of the tachometer. The new wiring harness for the control does not have a gray wire. There are several gray wires on the motor but I have no idea what wire to connect. Any help would be great.
Thanks in advance.
alfa posted 10-08-2006 03:29 AM ET (US)     Profile for alfa  Send Email to alfa     

First, check the rectifier.
Then see the following link.

seahorse posted 10-08-2006 07:47 AM ET (US)     Profile for seahorse  Send Email to seahorse     
Your motor has an air cooled finned regulator on the stb. side of the motor and the tach signal comes out the gray wire. You have to make sure the wire has continuity all the way to the tach S terminal.

Your wiring harness, if it is the factory one, has 3 wires coming out of it for a standard tach, purple, gray, black, as long as you have a 2" System Check gauge with the 4 warning lights. For best results most folks use a System Check tach with the lights inside it and the only hookup is the 8 pin connector from the wiring harness.

If everything is wired correctly, then you may have a bad regulator, or possibly a stator, that will have to be tested and replaced. Neither one is a cheap component.

If there are wing nuts on the battery connections, a bit NO-NO, that may have been the cause if the regulator is no good. Battery connections require lockwashers and hex nuts for security.

David C posted 10-08-2006 08:09 PM ET (US)     Profile for David C  Send Email to David C     
Seahorse and Alfa,
Thanks for the replies. After looking into it a little more, I see that the factory wiring is still in the boat (from the first motor). The mechanic installed a new control box when he changed the motor out. I think (I hope) it is simply that the wire was not connected from the old harness to the new harness. If this is not the case how do I test the stater and or the regulator?

I do not have the 2" system check guage on my boat. I only have a standard tach with four post on the back (universal). I know how to test all the other connections but I don't know a safe way to test for the "S" post from the motor.

I am with you on the lock nuts on the batteries. When would the damage to the regulator or stater have occurred, if that is what happened. I know the wires have never been or came loose while the motor has been running.

Thanks again for all the help and sorry if I am asking stupid questions.

seahorse posted 10-09-2006 01:31 AM ET (US)     Profile for seahorse  Send Email to seahorse     
Your motor required the 4-lite System Check gauge (or tach) when new to keep the warranty in force as that is your engine warning system.

From your description, someone either jury-rigged some wiring together on your boat or didn't know what they were doing. Ask your "mechanic" to test the warning system for you and to show you how as that is part of routine maintenance.

Stator and regulator testing is in a service manual. A loose battery connection, or reversed polarity could damage a regulator at any time.

David C posted 10-09-2006 10:57 AM ET (US)     Profile for David C  Send Email to David C     
Part of the problem is the lack of a decent mechanic in this area. I only used this guy from lack of options. He installed a new control box and for the life of me I cannot find a gray wire in it. What can I do to test for the correct wire in the new harness. The control box has Bombardier on the side of it. Everything looks to be connected correctly under the engine cover but at the control box there are a couple of plugs that are not connected to anything, with the use of a lot of electrical tape. I have no clue what this guy did but it looks like it is my only option to find out and correct it.
What do I test or look for to tell if the stater or regulator might be the problem?
Thanks for all your help.
David C posted 10-19-2006 12:51 AM ET (US)     Profile for David C  Send Email to David C     
I had time to get back to this problem. I have continuity between the gray wire on the motor and the back of the tachometer. I still have no read out on the tachometer. The tachometer will zero when the key is turned on but that is all it will do. I cannot get anything out of any of the area mechanics. They must be so busy they don't have time for the little things.
Can anyone give me a place to start testing to find out what needs to be fixed? I need to get a tachometer working on this motor. I don't like using it without the tachometer working properly.
Thanks for all the help.
alfa posted 10-19-2006 05:38 AM ET (US)     Profile for alfa  Send Email to alfa     
David I just bought a TeleFlew for my 70hp OMC.
Not mounted yet (lot of work on the 15').
a)Tach will zero when tension applied - key turned on is correct.
b)Connected to the gray wire, ok.
c)The calibration must be on 6p I think, check installation sheet.
d)Run the engine and check with a voltmeter the tension DC (Direct current) between grey wire and ground. (If I remember about 12vdc).
d1) If voltmeter shows no tension, check wiring and rectifier.
d2)If voltmeter shows tension, that doesn't means the tach is not working. I've seen some little mods required to adapt the tach (with some resistors).

Good luck

seahorse posted 10-19-2006 07:39 AM ET (US)     Profile for seahorse  Send Email to seahorse     
Your motor uses an air cooled rectifer/regulator assembly that runs just over $200 and can be ruined by reverse polarity at the battery or intermittent connections such as loose wing nuts on the battery terminals. That is why Johnson and Evinrude have required lockwashers and hex nuts for over 20 years.

The regulator has a separate circuit inside that generates a pulsing DC voltage for the tach. It can be tested by using a DVA adapter on a digital meter or a special peak reading voltmeter.

The stator needs to be tested per the service manual for proper resistance and for any shorts to ground.

If you do not have the manual and the specail tools, you will either have to hire someone or play "poke and hope" by replacing parts until it works.

David C posted 10-19-2006 10:48 AM ET (US)     Profile for David C  Send Email to David C     
Thanks for the replies.
Everything is set according to the instructions. The "calibration" adjustment is set on 6. I have not tested for voltage on the gray wire while the motor is running. I am going to pull the boat out of the basement and try that today.
I have a Fluke test meter that I think will read peak voltage pulse. At least that was one of the things the guy on the tool truck told me when I paid him hundreds of dollars for it. I am trying to find a manual but I am waiting on a few replies to make sure to get the correct manual for my motor.
Thanks for all the replies and help so far. If someone could give me the correct resistance from the manual, I could check that out in the next couple of days as well.


alfa posted 10-19-2006 01:03 PM ET (US)     Profile for alfa  Send Email to alfa     
David I don't have OMC manual.

Teleflex install doc (page # 3)has advice :

Connect a voltmeter between SEND and GROUND connection. With the engine at approximately 2000 rpm, it should read about 3-7 volts AC. This will confirm the presence or absence of a signal at the tach.

The Fluke is perfect for this test.

alfa posted 10-19-2006 01:35 PM ET (US)     Profile for alfa  Send Email to alfa     
Just a tought...

You said "My tach did not work after the new motor was installed".

I think your tach is ok. But something is wrong with the installation of the new motor.

The rectifier of my brand new Black Max was shot by the mechanics because they disconnected the battery. The tach didn't work. I had to change the rectifier.

David C posted 10-19-2006 06:45 PM ET (US)     Profile for David C  Send Email to David C     
Thanks for the help.
I called the mechanic where I bought the motor and he told me he was closed until Spring. In short I guess that means that I am on my own and will not be getting it fixed from him. Even though he told me that if there was a problem with anything on the motor that he would make it right. LOL

After several conversations with other in my area. I think I found a guy that may know what he is doing. The bad part is he is a couple of hours from me. I called him and he said to bring it down today and he could tell me in a couple of minutes if it was the regulator. He disconnected all the regulator wires and tested them (he said for any shorts). The ones that he showed me all went to dead short on the meter. He said the bad news was that the regulator was shot and it would cost around $230 for a new one. Any suggestions where to get the best price and even if the mechanic is correct. This is a pretty pricey item for a motor that was suppose to be in perfect working order.


alfa posted 10-20-2006 02:22 AM ET (US)     Profile for alfa  Send Email to alfa     
Yes, bad new,

Seahorse was rigth.

I' Bought some parts from MPO :

Call them :
Call Karen Maestre at 321-453-1111
They have new and used parts.

Hope this helps

David C posted 10-20-2006 02:22 PM ET (US)     Profile for David C  Send Email to David C     
Thanks again for all the help.
Marine parts outlet had a used one for $114 plus shipping and it is on the way. The guy that I got the motor from told me I was on my own and I will be sure to pass on how good him word is.

Thanks for ever thing guys.

David C posted 10-24-2006 09:11 PM ET (US)     Profile for David C  Send Email to David C     
Different day and still the same problem. The voltage regulator came in today and I just installed it. It is still doing the same thing as it has always done. I tested the old and new (the used one that came in today) and they both have the same reading for resistance. Nothing is showing dead short like the mechanic told me it did. Can anyone let me know what the correct specs for resistance on the voltage regulator should be? I should have checked the resistance for my self before I ordered anything but I was told I could trust this last mechanic. I also checked voltage on the gray (send) wire and with the motor started it goes to negative voltage. The ignition and light on the guage reads the correct positive voltage but the send is going to negative voltage relevant to the RPM's of the motor (the higher the rpm's the more negative the voltage).
I am out of options for a mechanic in my area. If anyone can help it would be much appreciated.


alfa posted 10-25-2006 07:32 AM ET (US)     Profile for alfa  Send Email to alfa     

You have signal on Tach.... Negative voltage wich varies with rpm. Between which values ?

David C posted 10-25-2006 10:03 AM ET (US)     Profile for David C  Send Email to David C     
I could only do limited testing last night. The negative voltage was around -.16 to -3 volts. Depending on if at idle or giving the motor a little throttle. I was not able to run the motor for very long or to give it a lot of RPM's.


alfa posted 10-25-2006 10:16 AM ET (US)     Profile for alfa  Send Email to alfa     

It seems that you rectifier is dead. I don't know the '99 motor, but mine (1988) 70 has a small rectifier on the side. If I remember, it is hold with 2 bolts.

This is one method of testing (Your Fluke has ohm-meter function) :

Remove the rectifier wires from the terminal block. Using a ohm meter, connect the black lead of the ohm meter to the rectifier base (ground), then one by one, connect the red lead of the ohm meter to the yellow, yellow/gray, then the red wire (some rectifiers may also have a yellow/blue wire. If so connect to that also). Now, reverse the ohm meter leads and check those same wires again. You should get a reading in one direction, and none at all in the other direction.

Now, connect the black lead of the ohm meter to the red wire. One by one, connect the red lead of the ohm meter to the yellow, yellow/gray, and if present, the yellow/blue wire. Then reverse the leads, checking the wires again. Once more, you should get a reading in one direction and none in the other.

Note that the reading obtained from the red rectifier wire will be lower then what is obtained from the other wires.

Any deviation from the "Reading", "No Reading" as above indicates a faulty rectifier.

Let's see the result.

alfa posted 10-25-2006 12:03 PM ET (US)     Profile for alfa  Send Email to alfa     
If this can help to locate parts :
It sems that the 99 has not the same rectifier as the 1988.
David C posted 10-26-2006 11:17 AM ET (US)     Profile for David C  Send Email to David C     
Thanks for the help.
I will try this out later today and let you know what the results are.

David C posted 10-26-2006 01:58 PM ET (US)     Profile for David C  Send Email to David C     
This is what I found in testing the resistance.
With the black lead from the meter to the case and then the red lead to the case. The only wire that shows resistance both ways is the gray wire. The red wire is the only wire that did not show any resistance with the black lead connected to the case of the regulator.

With the meter leads connected to the red wire all the wires show resistance except for the gray wire.

I tried the 200ohm resistor to the ground and the send on the tach and it did nothing.

Thanks again.

alfa posted 10-26-2006 03:26 PM ET (US)     Profile for alfa  Send Email to alfa     

Don't have the shop manual for your motor.
Hope Seahorse has an advice.
For me this rectifier is not in good shape.
You have strange signal on the tach...
For me, the rectifier is a diode full-bridge. A diode only conducts in one way. (I'm a ham)

I'm not an expert in outboard motors and don't want to lead you in expenses. My rectifier is cheap, about 25$.
Have you checked you have no loose connection ?
Sorry, not easy to check from long distance.
Did you test with the 2 tach.
But I believe something is wrong with your motor. You changed the Power pack. But this rectifier...

alfa posted 10-27-2006 03:37 AM ET (US)     Profile for alfa  Send Email to alfa     

Let's forget the rectifier for now.
If regulator is ok, the pulse for the tach is provided by it. This pulse comes primary from a circuit from the stator.
For checking that stator and to have the right drawing circuit, the shop manual is necessary.

David C posted 10-27-2006 01:42 PM ET (US)     Profile for David C  Send Email to David C     
After all of this it is now working. The regulator was not getting ignition power from the purple wire. Some one had cut the purple wire and taped it back into the wiring harness. I know have an extra voltage regulator if anyone needs it. I am sorry for any waste of anyones time and I very much appreciate all the advice and help. Chasing things like this down is useless with out a service manual. Lesson learned for the future, have the manual before you start buying parts.

Thanks again for everything and to everyone.

alfa posted 10-27-2006 02:10 PM ET (US)     Profile for alfa  Send Email to alfa     
Thanks for reporting about this ending David. And glad it works. Yes, troubleshooting without the right shop manual is rather difficult.

Enjoy your boat

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