Charging system issue

[ghobb2kw]

I have a 2003 XLT 5.4 4X4 that was having an issue with the fuel pump relay (common issue as I have read). So I went out to a pick a part and got a replacement fuse block and swapped it out. First time starting it after the swap out it fired up fine and ran well. However the red battery light came on and would not go off.

checked the fusible links going from the alternator to the battery and everything was fine. And the alternator was working fine prior to the fuse block swap out.

I was looking for an alternator fuse thinking that the fuse block I had put in had a blown fuse for the alternator fuse #9 I believe and there is not a place for a fuse number #9 on the “new” fuse block. I googled a picture of the fuse block for a 2003 expedition and it is also missing the #9 fuse position.

so I am wondering if there is a way to add a fuse to complete that circuit and get the alternator to charge the battery again. I know the fuel pump relay can be bypassed to get the truck running but what about the alternator. I did have a 01 F-150 that I had accidentally left the alternator fuse out while running that vehicle and it ran fine until the battery started running down and I realized what happed and the fuse and it charged normally so I’m thinking this may be a similar situation.

thank you for any help

 

[stamp11127]

The 2003/2004 have known issues with the smart junction box and as you have found out are not completely swappable between years.

One option is to compare the charging system wiring circuits between the 2 and modify as necessary.

 

[ghobb2kw]

Do you know what plug that comes off of the alternator harness would be the one I would modify? There is one with 3 wires and one with 2 wires. Any idea which one is looking for a fuse?

 

[stamp11127]

These may help