Alternator fuse blows every time battery is connected?

JEWELSLYNNE79

MEMBER
2005 MERCURY MONTEGO
3.0L
V6
4WD
AUTOMATIC
189,654 MILES

We had replaced the battery and the alternator and now we are dealing with the alternator fuse that's under the hood in the fuse compartment, it's a 10-amp fuse for the alternator that every time we connect the battery and go to start the car it will blow the fuse. We have traced all three wires to the alternator and checked the fusible links and they are all good and wires are good, but now we don't know why the fuse keeps blowing every time the battery is connected.

Saturday, November 26th, 2022 AT 7:02 PM

1 Reply

JACOBANDNICKOLAS

MECHANIC
110,052 POSTS

Hi,

I need you to try something. At the alternator, there is white wire with a black tracer. That wire is what connects the fuse you mentioned with the alternator. Disconnect that wire from the alt and see if the fuse still fails.

If it does, then there is a short between the fuse and alternator so confirm the connector is in good condition and there is no evidence of it being damaged. Do the same with that wire.

If the fuse doesn't fail, suspect either the connector on the alternator is bad and causing a short or the new alternator has an internal short.

I attached the wiring schematic below, so you have a reference.

Let me know what you find or if you have questions.

Take care,

Joe

See pics below. Note: I had to cut the pic in half to make it readable. I did overlap the two halves so you can follow from one to the next.

Images (Click to make bigger)