Wiring harness melting

Dirty 78

Recruit
Joined
Sep 16, 2017
Messages
2
I have a 1990 johnson 48 spl have never had any problems with it. Recently I went out to charge battery and before I hooked up charger I could smell something electrical had burnt.discovered my wiring harness between plug on motor and ignition had.melted and caught on fire. Assumed the harness was old and had worn a hole threw insulation and shorted out on aluminum boat somewhere. Everything was severely melted so it was hard to tell. Got new harness and it started getting hot as well. It is definitely the ground wire in harness getting hot. Don't even know where to start. Cables from battery to motor are good and clean, cleaned grounds on motor any ideas?
 

GA_Boater

Honorary Moderator Emeritus
Joined
May 24, 2011
Messages
49,038
Welcome aboard.

This is a guess - The heavy ground cable to the battery is bad and when the motor is started, the starter current path is through a small gauge wire in the harness leading to meltdown.
 

82rude

Rear Admiral
Joined
May 8, 2012
Messages
4,082
I would say thats a pretty good guess as thats exactly what my issue was a few motors ago.
 

Dirty 78

Recruit
Joined
Sep 16, 2017
Messages
2
Would this cause it to happen when ignition is turned off? First harness burnt up between lake and my house or while sitting outside my house. Didn't happen while in use. New harness got hot with key in off position as well.
 
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