Alternator not charging, PCM not sending signal?

[pepsi71ocean]

So I pulled the alternator out to swap the rectifier, and found the alternator brush pack garbage, so I pulled the old Napa alternator out and swapped the rectifier into it.

I installed the alternator into the truck and hooked the batteries up. Then I started it and checked AC voltage, got .025vac, then switched the volt meter to DC, and it read 12.25v. Puzzled I checked the idiot gauge and sure enough it wasn't charging.

I then pulled the old alternator out put it back in and now the truck is still not charging.

I took the charging lead off the alternator and it is .05v.

I haven't checked for codes, but I will when I locate my scan gauge 2.

Anyone have any ideas?

[dripley]

voltage regulator in the PCM? Battery temp sensors bad? just guessing since I am a 3rd grader on electronics.

[Vais01]

So I pulled the alternator out to swap the rectifier, and found the alternator brush pack garbage, so I pulled the old Napa alternator out and swapped the rectifier into it.

I installed the alternator into the truck and hooked the batteries up. Then I started it and checked AC voltage, got .025vac, then switched the volt meter to DC, and it read 12.25v. Puzzled I checked the idiot gauge and sure enough it wasn't charging.

I then pulled the old alternator out put it back in and now the truck is still not charging.

I took the charging lead off the alternator and it is .05v.

I haven't checked for codes, but I will when I locate my scan gauge 2.

Anyone have any ideas?

Try ramping up your RPM to near 1200-1500. Normally they do not produce a full voltage until a higher RPM.

[pepsi71ocean]

I tried raising rpms.

I suspect the pcm or the wiring.

[cbrew]

have you run a continuity test on the field coil ?

you should have 12v on one pin of the field connector (Blue wire IIRC) but its a 50 % chance

 

if the two above are true, then i would look at the bridge again

[pepsi71ocean]

Update, I went to move the truck and have lost 1st and 4th gears.

No check codes showed up.

I'm about stumped on this.

[Vais01]

Update, I went to move the truck and have lost 1st and 4th gears.

No check codes showed up.

I'm about stumped on this.

Look at your PCM ground should be next to or below the airbox. Clean everything off and reinstall. Now if you have lost 2 gears that is the PCM based issue. The PCM connector for the transmission communication is closest to the engine. The PCM is bolted to the firewall behind the airbox. Try pulling the connections and cleaning with electrical cleaner.

It sounds like you are in limp mode.

Edited August 21, 2015 by Vais01

[pepsi71ocean]

I know I'm in limp mode, and I suspect the pcm is not getting any power, I didn't even think of checking the cruise control.

I wish Mike was around.

[Mopar1973Man]

Pepsi check your voltage regulator for the transmission. I bet that wire came loose.

[pepsi71ocean]

Well the pcm is not sending the 12v signal to the alternator or the transmission relay, so it is dead as Mike thinks.

Mg question is where to find a new one as from what I have heard is that all rebuilds are crap.