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stevebo

551 Suburban Electrical Help

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I recently picked up a 551. I am trying to redo all electrical on it. The wiring diagram shows only 2 leeds on the key switch but mine has 3. The switch is correct from what i can see. Can anyone confirm what two leeds i should use? I believe the third is a ground but not sure. The diagram is not very clear...

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The 551 and 701 both show the solenoid as # 3657.

Take a look at the 701 diagram to see how that one is wired.

Noticed this a long time ago but have never seen anyone question the solenoid or the wiring till now.

 

Garry

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From what I can see on the diagram there is no way to shut the engine off.  So I think your 3rd terminal connects to the points in the motor to ground it to shut it off. 

Agree ?  :think:

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THIS IS WHAT I'M THINKING...

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1 minute ago, N3PUY said:

THIS IS WHAT I'M THINKING...

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I agree with what you are thinking but I need to run the top one to battery still and question is what terminal on key switch to  kill engine?

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Just now, stevebo said:

I agree with what you are thinking but I need to run the top one to battery still and question is what terminal on key switch to  kill engine?

TERMINAL ON SWITCH TO KILL ENGINE IS MARKED "G" OR "GND".   With the key in "OFF" position that terminal should be grounded to switch case. 

Can be tested with ohm meter.

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1 minute ago, N3PUY said:

TERMINAL ON SWITCH TO KILL ENGINE IS MARKED "G" OR "GND".   With the key in "OFF" position that terminal should be grounded to switch case. 

Can be tested with ohm meter.

Perfect. I have it wired wrong to key I think.

How about the terminal from the key to the selnoid? I assume the s and the last one leave open.

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Looks to me like the solenoid small terminal is hot all the time. The ignition switch would ground the solenoid terminal to activate it. At least that is what the 701 wiring shows and they both use the same solenoid.

The 551 does not have a pushbutton for the starter does it?

 

Garry

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The 701 wiring is a lot different. The starter key switch is a 3 position.

 

The 701 has a 2 position on/off 2-prong key ignition switch that grounds the ignition.  A seperate starter button switch (unique to the 701) engages the starter/generator.

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I just had glark (Matt) route the wires on his and he said the s terminal goes to the solenoid, the g is a ground and the M terminal goes to the points. the top right goes to the battery or in his case the positive leed o the solenoid. 

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20 minutes ago, formariz said:

Here you go!

 

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Yes sir, based on all the info everyone gave I believe the number 2 set up is correct.

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Set up #2 is the correct one for 551 .

If you need diodes I have them!

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1 minute ago, formariz said:

Set up #2 is the correct one for 551 .

Yes the only thing it does not show is the third terminal which is a ground. 

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Posted (edited)

Your switch has 3 prongs?

Should only have two. It should be case ground. You may have wrong switch. I will check mine tomorrow. It is the original.

 

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Edited by formariz
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On ‎2017‎-‎03‎-‎06 at 8:21 PM, stevebo said:

I just had glark (Matt) route the wires on his and he said the s terminal goes to the solenoid, the g is a ground and the M terminal goes to the points. the top right goes to the battery or in his case the positive leed o the solenoid. 

Double check this. I don't think the ignition switch has any battery + power. The ignition coil will be compromised.

I think the ignition switch simply grounds the ignition wire to shut it off or grounds the solenoid coil to activate it.

The small solenoid terminal should be tied to one of the large solenoid posts. Check with an ohmmeter. That would be the one coming from the battery +. The other large terminal goes to the starter motor.

 

In the beginning one 3656 ignition switch had one terminal and grounded the ignition to shut it off. This switch was replaced by 6890.

The second 3656 ignition switch had 2 or 3 terminals and kept the 3656 part number. If 2 terminals the body of the switch provided the ground to the chassis.

 

I'm thinking it is the solenoid that is unique.

 

Garry

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Posted (edited)

The solenoid is indeed unique. It has an internal ground activated by switch. Correct switch should have the magneto ground connection attached to it and the other terminal goes to solenoid. The other two heavy gauge wires on solenoid go to battery and starter. Switch only activates a ground connection to start tractor by opening solenoid and grounds magneto to shut engine off when turned the opposite direction.

Careful, do not apply voltage to magneto! You will fry it and probably never find a replacement.

 

Both correct switch and solenoid not the easiest things to find if you need to replace them.

 

Looked at mine this morning to refresh my memory. It has been a while since I worked on these. On photos ignore relay, I have lots of wiring for many different things on it. I have wired everything else with same principle in mind. Everything is activated by a ground. Pretty much like old Toyota trucks.

 

In my opinion of all the wheel horses that I have worked on , the 551 is the hardest and most complicated to work on.Not only electrical system is a little unusual, there is so much stuff cramped under hood that it is difficult to get at or see properly. The fact that hood is hard to remove makes it really bad.But on the other hand if you remove the hood then getting throttle and choke cables right is another adventure.

 

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Edited by formariz
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Oh!!!  In the "OFF" position the magneto wire is grounded.  In the "RUN" position there is no connection made.  In the "START" position the solenoid wire is grounded thus closing the solenoid using power from the battery cable.   That's really French if you ask me. :techie-eureka:

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If you want a real head scratchier try to understand the GM variable speed intermittent windshield wiper wiring system.  :confusion-confused:

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Cannot tell from photo but I am sure there are markings on it.In any case there would not be any harm done. If it does not work reverse them. Or check continuity with a tester as you turn the key. When key is turned all the way to the right there should be continuity on terminal that should go to solenoid. Releasing key it will go to the neutral or run position. Turning to left there (off) there will be continuity to terminal going to magneto grounding it , therefor shutting off engine.

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I will test it but I am not sure the solenoid I have on it is correct. Do you have a part number for that?

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