Blowing Fuses

[alldodge]

There has to be more then 2 wires.
1-supplies battery voltage
2-supplies voltage to run system (when key is turned ON)
3-supplies power to start relay to crank the motor over

 

[TimTJR]

There are more than 2 wires. I was just saying in relation to the red/ purple wire, there is only red and only purple. There is no red/purple.

-There is 1 yellow/red, 3 red wires, and 3 purple wires, and 1 heavier gauge red wire.

-The yellow/red wire is on one post.

-There is one heavier gauge red wire on one post.

-There are 2 red wires on one post. One has a 5 amp inline fuse .

-There are 3 purple wires on one post. One has a 5 amp fuse .

 

[achris]

:facepalm: This is not a standard Merc key-switch. It's some aftermarket dodgy attempt to simulate a car ignition switch.

Ok, power in is the big red one. The yellow/red is to crank the engine. The purple is key ON (check by confirming one of them goes to one of the gauges (like the tacho). I suspect the 2 small reds are for 'accessories'.

Suggestion.... Remove those and get any non-engine electrics off the engine electrical system. Run a 6mm red and black from the battery switch up to a red and a black terminal block and run all your other electrical equipment from those. And change any glass fuses holders for mini-blades.

Like this....



Chris..........

 

[alldodge]

-The yellow/red wire is on one post.

-There is one heavier gauge red wire on one post.

OK, these are good, don't change them

The question is your blowing a fuse
First if the 5 amp fuses are in tact and not blowing, disregard them. This leaves one red and 2 purple wires.

Can you post a pic of your key swicth?

Most switches only have 3 post, so I'll assume you have an accessory position

The main concentration are the 2 purple wires without the fuse. One is power to the system and the other is power to something else. Need to trace the 2 wires

 

[alldodge]

Thought about this some more, and where getting off track. Your current issue is there is no power to the coil with the new diode in place. With the old shorted diode in place there is power to the coil because the Red/Purple fused wire back feeds the coil thru the diode.

The motor was running fine until the fuse started blowing which did kill the motor. So there is an open circuit between the key and the purple wire feeding the coil. With 12V on the the Red wire at the key, then its not the 20 amp fuse on that wire. So it has to be the purple wire which goes thru the kill switch, by every gauge, to motor plug, to the coil.

There should be 12V at the key (red) and have 12V on one if not both or the purple wires when key is turned ON. One of the purple wires goes thru the kill switch.

So verify power, then jump across the kill switch to bypass

 

[TimTJR]

I forgot to follow up on this post. I fixed the problem. achris was right. The problem I found was the temp switch had bare wire rubbing against the motor. Replaced the temp switch and no more blowing fuses.