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John Deere SX75 ignition wiring?

syzygy's Avatar
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06-02-04, 02:40 PM   #1  
John Deere SX75 ignition wiring?

I inheritied a John Deere SX75 9HP riding mower. Before I invest a lot of parts and money into it, I'd like to see if I can get it running.

What I need is the wiring configuration I need to try to start it.

Connecting battery directly to starter turns over but doesn't allow spark. I have no key, and can't find a replacement key that will work yet, even from the dealer. I won't mind a new ignition once I verify it will run. Wonder if anyone knows what wires I need to jumper to try a start?

PS - it's got a wiring harness that connects to 5 posts, and a separate one that connects to a 6th post.


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cheese's Avatar
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06-03-04, 12:10 AM   #2  
Hello syzygy!

Unplug all conectors coming from the engine except the small white wire that plugs onto one terminal on the igniter ( a small metal square screwed onto the side of the engine). Then crank it. This will isolate the engine from the mower's wiring harness. You will have to apply power to the starter cable and jump to the solenoid terminal.

"Who is John Galt?" - Ayn Rand (Atlas Shrugged)

God bless!

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06-03-04, 04:38 PM   #3  
Note that unplugging this wire will not allow you to shut it down by normal means - you will have to use an insulated set of pliers and pull the spark plug wire off (or reattach the wire). I suspect the reason it won't fire is due in part to the fact you are not on the seat when you are jumping it, therefore, the safety switch is not triggered and you will have no spark as a result. Using a helper should take care of this problem.

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06-21-04, 05:44 PM   #4  
I figured out the wiring... ignition not only wouldn't accept the key, but once I ripped it apart and it would, the rusted spring for temporary on (for start) wouldn't allow it to turn far enough.

I'll probably end up getting a new ignition eventually, but for now I hooked up my own switches. I'll need a new gas shutoff valve since it's leaking, but not sure how to remove it.

Before this, I did test turnover by either jumping solenoid post to ground, or touching the two red posts with big screwdriver to attempt start.

For anyone else who may see this in the future...

Wiring diagram for John Deere SX75 rear engine riding mower:
(Looking at the wiring harness that plugs into the ignition)

1 - - 2
3 - - 4
- 5
/ 6

Off: 1&2 connected
On: 1&2 disconnected, 3&6 connected
Start: 1&2 disconnected, 3&6 connected, 4&5 connected (start)

Hope that's clear enough and helps someone.

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