Need some trolling motor wiring advice!!

so I have a 14ft tracker, I installed a older Johnson 24v TM. I ran the batteries in series, nothing else attached to batteries except the TM.

So I had the power wire for the TM hooked up and while I was crimping the ground wire (the ground is already connect to the battery) to the TM my tool touched the boat and I notice a slight spark. I put my test light on the battery ground and probed the boat and it lit up. If I remove the power cable from the battery the test light doesn't light up. Seems like my TM is grounding out the boat with power.

Is this normal?
This is a older Johnson TM model: BFL4TPV

The TM works at all speeds, nothing seems out of the ordinary, no warm/hot wires.

I can post pictures up later if needed, Thanks

 

Hey bud. New here to Tacoma world and was just surfing around. I dabble in boat stuff. Def sounds like your grounding to your boat. I’m pretty sure the ground should go to the negative terminal. Grounding to the hull on an aluminum boat will cause electrolysis and slowly but SURELY cause it to corrode.

 

Might have spark welded the wire somewhere to the boat? Check length of the wires and connections

 

So, after tinkering around, I left the trolling motor still hooked up but insulated it off the boat and found the complete trolling motor is the source of grounding. I'm assuming that maybe that's they way Johnson made their TM's.

On a fiberglass boat you wouldn't have this problem.
Maybe I'll have to find a different way to install it so it doesn't ground to the boat.

 

Thats weird..id get a thin rubber mat to cover the exposed area of the trolling motor