Accidentally grounded 12v power under dash

tango13

Petty Officer 3rd Class
Joined
Mar 10, 2015
Messages
75
Made an absolute bonehead move - a few weeks ago I pulled the tachometer to measure it, and for whatever reason, I threw all the wiring back in all the wrong spots. A couple nights ago, I turned on my batteries and went to hit my hood ram switch (located beside the tach), and it didnt work! So I tried a few other switches to see if my battery was dead (lights, blower, ect) and all worked. I then turned the key to the on position, and noticed my alarm wasnt buzzing. Toggled a couple times and still nothing. A few seconds later, as I went to peak under the dash (while the key was on), felt that the power supply from the key as super hot and then noticed a little puff of smoke from the wiring, and immediately turned off the power. My bonehead move on the tach resulted in me accidentally throwing the power wire on the ground. (my good switch ground was on the SIG connector, hence why it wasn't working).

Anyways, I found the melted wire - about a 4 inch stretch of wire coming from my kill switch at the shifter, which is powered from the key from what i can tell. I temporarily taped the damaged wire, and re connected everything correctly, and it seems like everything is good again - Key alarm comes on, everything powers on, ect. From what I can see, thats my only melted wire. Ive looked around the harness at the engine side, and everything looks fine

Now my obvious concern at this point is whether I damaged anything else. I THINK that circuit is power from the key > kill switch > tach (where I grounded it) & ignition coil, thought I'm not 100% sure (its hard to tell with the harness). From what I can tell, only a small portion of wire melted - about a few inches of wire that was crimped on both ends. As far as I can tell, everything is fine, though the boat is in my garage on the trailer, so I cant fire it up to be sure the ignition is fine. Engine is a 1995Mercruiser 7.4/Bravo 1 with the T-bolt ignition system.

Yes, I know I need to check connections with a multi-meter. No, I don't know how to use one. I have a friend coming to help check connections in the next few days. I know very little about electrical, so forgive my ignorance.

Thanks in advance
 

dingbat

Supreme Mariner
Joined
Nov 20, 2001
Messages
16,313
Circuits are typically individually used. If the fuse protecting that shorted didn't blow, pretty good you did no harm.
 

tango13

Petty Officer 3rd Class
Joined
Mar 10, 2015
Messages
75
Had a friend come over with a multimeter and we did some poking around, full 12v to the coil and wasn't able to find anything else melted. Will replace the melted wire and keep on trucking, with a fire extinguisher on hand :)
 
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