Repairs John Deere L120 Magneto Question

[jeff1967]

Hey Guys,
New to the forum. Replaced the engine(Intec 20 hp Briggs) on my L120 with a running used engine. I adjusted valves and cleaned magnetos. As I was working on magnetos, I noticed a black wire not connected to the left magneto. Engine seems to run fine. The problem is when you connect the black wire, the engine dies. Both were connected on the old engine. Any suggestions?

 

[ILENGINE]

That wire should have a diode or two in the wire between the modules, If the diode goes bad it will cause the modules to ground each other.

 

[jeff1967]

The diode, or lack of one, was the problem. The previous owner had cut the diode off and spliced the two wires back together. I took the one from my old engine and put on the new one. Runs perfect. Thanks for the advice.