Alternator protection

[wil440]

I've finally got around to do the alternator protection fuse, well I checked wiring diagrams just to be sure on which wire and which PCM pin, it's ingrained in me to check,check and check again before snipping wires.

Anyway I have a question, is there any reason the green (this is pin 10 conn 2) isn't on the list to fuse protect, my wiring diagram (2001 Dodge FSM) says Blue is neg and Green is pos of the alt field windings, I'd have thought it would be safer to fuse both.

Lets say the FSM I have is right and I have no reason to think not (paper BTW) and the green is pos and it shorts to earth somewhere in the harness  which BTW is 5ft longer than it needs to be or a short in the alternator then as far as I see it the pcm may well have to pass a fair amount of amps before a wire burns through or other fuses blow ??

OR am I talking like an idiot.....

[IBMobile]

This is the voltage and amperage on the blue wire when i tested it with a load.  I had the amp meter hooked up backwards for that mines sign.

 

 

 

 

[Mopar1973Man]

I'm still running the 5A fuse I started with one year ago. Fuse is installed on the blue wire NEAR the PCM. Not long ago a another member just had his 5A fuse blow  from a failed alternator and after replacing the alternator and fuse its back to working. 

 

Edited April 7, 2020 by Mopar1973Man

[wil440]

I've added a fuse on the blue wire, I'm curious as to what you think about adding a fuse to the green wire which is pin 10,conn 2 at pcm. My diagram says this is pos and blue pin 25 conn 3 is earth, I'm thinking if there was a short on the green there would be some amps through pcm and did I read somewhere on here pcm fuse is 20 amp so pcm would be at 20 amp before fuse blows right ????  

[Mopar1973Man]

Green wire if it shorts it just charging at maximum rate. Field load prevents failure. Blue wire shorts to ground is instant PCM death.