Why does my tractor only start when I bypass the "Starter Circuit Relay"?

On a '97 Lull 644B-37 highreach (shooting boom) forklift. Without a key, loosen one wire on SCR and touch it to the other briefly, causes the starter runs indefinetly til you put the key in the ignition and turn to "on" position, then tractor starts!! OR with key in the ignition, at "on"... show more On a '97 Lull 644B-37 highreach (shooting boom) forklift. Without a key, loosen one wire on SCR and touch it to the other briefly, causes the starter runs indefinetly til you put the key in the ignition and turn to "on" position, then tractor starts!! OR with key in the ignition, at "on" position, barely touch wires together and machine starts!

The part I replaced today was a "Starter Circuit Relay" .. Part # RE170320 But didn't help anything.
Update: John Deere engine model 4039 DF
1 answer 1