LH-IG fuse keeps blowing

Ok question. Does power first go through the ecu, then through the fuse panel under the dash, or from fuses to the ecu?

 

^^^

 

It comes into the body control module directly from the battery and main fuse. As you turn the key on some relays close which then feeds power to the fuses.

If your 20A 4WD fuse and 7.5A ECU-IG No.1 Fuse both have power then at least ONE side of the LH-IG fuse should have power. You can see the red circle I drew showing the three are connected together. Almost impossible for the 20A 4WD fuse and 7.5A ECU-IG No.1 to have power while the 7.5A LH-IG is completely dead.

Are you using a good volt meter? Checking for power on both legs of the fuse?

 

Sorry if I wasn’t clear, but yes, I do have power to LH-IG. I’m about to replace the alternator again, which is thankfully under warranty, and see if that fixes it. I know what was causing my issue, and I have fixed it. It seems that I just blew the voltage regulator, or at least I hope that’s what it is and not some hidden surprise.

 

Did you put a voltmeter on the battery with the truck running to check voltage?


Power goes through the fuse into the alternator to enable the voltage regulator.

 

Yes I did this while the truck was running. Do you know of any wires I should follow to the alternator that I should check?