Sorry for the quick question without a search. I only have 2 min in front of the computer.

I checked my fuse box and it has a 120amp fuse for the alternator. Does that mean the alternator that I need to buy has to be a 117amp? Or is it as easy as bying a 140amp fuse and getting a 136amp alternator?

 

You probably have a 90 amp alternator. If you can find a 140 amp fuse, then go ahead and buy a 120 amp or 136 amp alternator

 

Mine truck had a 120A fuse and my alternator was a 117A, but I replaced it with a 136A and left the 120A fuse in because it's a slow blow.

 

O'Reilly Auto Parts only offers 90amp and 136amp alternators for the truck. Can the wireing handle the 136amp alternator if I upgrade to a 140amp fuse? Or will I melt some wires? And do all three have the same bolt configurations and belt pully?

 

Mine was a direct replacement. From what I understand, the wiring didn't change between the different alternator choices. I'm leaving my 120A fuse in until I find a reason that I need to upgrade it to the 140A. Maybe someone else knows differently about the wiring, but I doubt they would use a completely different wiring harness because of the alternator.

 

But isn't running 136amp thru a 120fuse asking for trouble? If it blows while driving......not good. I don't know how much a 140fuse costs but it has to be pennies compared to the potential costs if you blow a fuse. Correct me if I am wrong. I generally steer clear of electrical issues.

 

The potential cost if you blow a fuse is the cost of a new fuse.

 

The voltage regulator regulates the output of the alternator based on the load (ie. stereo, Off-Road lights, winch, etc). So if you have your truck all decked out with a big stereo, a higher output alternator is needed to keep up with charging the battery and running the equipment.

 

I get that. That is not the issue. The issue is, I need to replace my alternator which is the stock 117amp. And my local auto parts store only carries 90amp or 136amp. I am running an all stock truck so no issues in needed extra juice.

 

The only way you are going to blow the 120A fuse is if you are running a ton of aftermarket lights or big stereo equipment. I have none of that now, so I don't have to worry about blowing the fuse. When I do add aftermarket off road lights and the such I will put in the higher fuse. Just get the 136A, it's always nice to have the extra capacity for the future and it will not cause you any problems.