Smoke from ignition switch

[Billfish_71]

Greetings and salutations to all, I am a first time poster to this forum looking for an answer to an electrical problem with my wiring harness/ignition switch.

The motor in question is a 97' carbed merc. 175 on a 22' cuddy cabin.

A few weeks ago, several minutes after anchoring to fish and killing the ignition, I observed a plume of smoke rolling out from under the console. I immediatly began to search for the source as the smoke slowly began to dissipate. After switching the batteries off I opened up the console only to initially find nothing. Well needless to say it was time to go. After turning the batteries back on and starting the motor I noticed the wiring harness was very hot to the touch and the tach. was reading 5000 rpm's at idle!
Fortunatly we were able to get the boat home without further incident.

A couple days later after removing the ignition switch for inspection I noticed that the potting on the back of the switch was all melted? If anyone has any input on this one it would be greatly appreciated. I don't want to just replace the switch and have this happen all over again. What else could cause such a thing to happen other than a faulty switch? I have also removed and inspected the entire harness and I really couldn't find a thing visually.....

Thanks in advance, Billfish_71

 

[vegasphotoman]

Re: Smoke from ignition switch

something unfused.......is grounding out big time...........find bare or melted wire and trace it back to a source of contact.

take off switch and wires....reconnect battery...if no hot wires...then somehow possibly the ign switch was internally grounding out...could happen...

heres a generic ignition switch wiring diagram for an old evinrude setup....might help?

http://i155.photobucket.com/albums/s311/frankr_photos/Wiring1963Speedifour75WithGenerator.jpg

well whatever is "shared" with the tech and the ign switch could be the culprit....LOOK CLOSER........follow the wires that are connected to the burnt switch connection........

Good luck!

 

[Faztbullet]

Re: Smoke from ignition switch

There is no un-fused feed to the ignition switch on this engine, if there was a short to ground the 20 amp fuse would have took a dump. Most likely moisture or salt build up in switch causing a high resistance or the tach took a dump and fed back thru purple wire to switch.

 

[Texasmark]

Re: Smoke from ignition switch

Older switches will make tracks and do this from usage and contaminants. Get a new switch.

Mark

 

[Billfish_71]

Re: Smoke from ignition switch

Thank you one and all for your advice, my local dealer has an after market switch for around 25 bucks. Hopefully the wire colors are the same, if not it should have a wiring diagram with it. I think soldering and heat shrink is the way to go on this project, no crimps!

 

[Willyclay]

Re: Smoke from ignition switch

Take care when using any non-OEM switch because the internal switch contacts could be different and cause other issues. Try to match the switch with your motor. Good luck!