Alternator

[ShinyC10]

Originally Posted by VetteVet

Your test is right and it's not showing the diode pack is grounded to the case.

Did you ever test the output of the alternator when the engine was running before the maxifuse blew? Red lead on the output stud and black lead to case looking for 13 to 15.5 volts.

If you are getting 16 plus then the alternator is overcharging and putting too much current through the MF and causing it to blow.

As long as you're not showing a short to ground through the alternator, I think I would run a bypass wire from the alternator to the junction without the maxifuse, and read the alternator output. Turn on all the accessories that you have and read the meter. I could be that you are simply using too small a Maxifuse or you need the fusible link. Most of our year vehicles do not use a fuse or a fusible link in the charging wire to the junction but everything from the junction is fused.

Yours is newer so they may have started using them when they changed the alternator routing to the starter solenoid.

I have been assuming that your truck has the 12 SI alternator so is that correct?

Sorry for the late update, hope you're still here.
Got a rebuild kit on the way from summit. In the meantime I put the alt back in with a 40amp maxi fuse and turned the truck on. I also turned the headlights on, driver door open, radio on and ac on and the alt stud was reading 14.06v while those were running. With the truck running with nothing on except the door open the stud was reading just around 14.56v. The one thing that bothers me is that my volt gauge reading drops down to almost 11v with everything on (radio, lights, etc.) all of his is with a 40amp MF

[VetteVet]

Originally Posted by ShinyC10

Sorry for the late update, hope you're still here.
Got a rebuild kit on the way from summit. In the meantime I put the alt back in with a 40amp maxi fuse and turned the truck on. I also turned the headlights on, driver door open, radio on and ac on and the alt stud was reading 14.06v while those were running. With the truck running with nothing on except the door open the stud was reading just around 14.56v. The one thing that bothers me is that my volt gauge reading drops down to almost 11v with everything on (radio, lights, etc.) all of his is with a 40amp MF

I would try moving the sensing wire over to the green accessory wire connection on the junction. Are your lights dimming at idle?

[ShinyC10]

Originally Posted by VetteVet

I would try moving the sensing wire over to the green accessory wire connection on the junction. Are your lights dimming at idle?

Not lights don't seem to dim at idle. What would be the differnce in the spot on the junction for the sense wire?

[VetteVet]

Originally Posted by ShinyC10

Not lights don't seem to dim at idle. What would be the differnce in the spot on the junction for the sense wire?

I was thinking that you might get a better voltage sensing from there, so the alternator could adjust for the voltage drops as you turned on the loads.

if the lights were dimming it means that he alternator isn't keeping up with the amperage draw on the system. You might not notice much dimming at 11 volts though.

Is the MF holding up?

[ShinyC10]

Originally Posted by VetteVet

I was thinking that you might get a better voltage sensing from there, so the alternator could adjust for the voltage drops as you turned on the loads.

if the lights were dimming it means that he alternator isn't keeping up with the amperage draw on the system. You might not notice much dimming at 11 volts though.

Is the MF holding up?

I didn't drive it but tomorrow I plan to. I just let it idle to see if the MF held up for that but tomorrow I'll find out. And the rebuild kit comes in