Chevy1999

Replaced starter in 1999 Chevy 3500 7.4 with new one from Amazon. Installed it then went to connect negative back to battery and starter kicked on without the key even in the ignition! Finally was able to connect the negative to the battery without starter kicking on. Turned key and truck fired up nice. Did this about ten times and truck fired right up each time no problems. Let it sit for about an hour and started it again. Again it started right up but the starter stayed engaged, turning the key off wouldn’t stop it so I had to disconnect the battery real quick.
Prior to this all happening I went out to truck to go to store and it wouldn’t start, just one click at starter. I assumed battery since it was old so I replaced battery. Same thing with new battery. So I removed the starter and bench tested it, worked fine. Was told that it could be weak brushes so decided to replace starter. That’s where I’m at now, any ideas?

Irish_alley

make sure none of the wires are touching on the starter and theyre tight

Chevy1999

They were definitely tightened down good. Going to check to see if anything is touching. Also going to check ground going to frame make sure it’s clean and tight. May just go ahead and replace the starter relay also in case the contacts maybe sticking.

Irish_alley

you have a starter relay?

Chevy1999

Yes! Going to replace it just to eliminate that as the cause. Went out to truck yesterday and it started right up, let it idle and within 30 seconds the starter engaged while engine was running. Again I had to run around and disconnect the battery real quick.