So my batteries were new 7 years ago....   they need to be replaced. they dont like holding a charge for long (couple months or less) and i think they are actually mechanically failing. I have had a battery tender on them for the past month in winterize mode to keep them fresh but even that showed limitations, as when i started today i could tell they were not as healthy as they should be.

 

i went to the dump to drop off metal and while there i had to shut down for 5 minutes waiting the scale lady and when i restarted it just cranked over for about 1.5-2 seconds longer then fired up (i noticed no dash power until it fired). as i moved to the metal shed at the dump it was not happy at all (on a downward incline) its like someone was switching ALL power off to the entire truck for a half second then back on.

 

it did this 4 more times while idling and sitting still (all power dropped, dash went dead as did the engine and when it came back there was a cel that cleared and all was fine)

 

i got home no problem and did an electrical test. all lights and accessory lights on fan etc etc "full electrical load" and was reading 13.72vdc on the main batt terminal and .080vAC on the alternator terminal. 

 

I know the batteries are in desperate need of replacing and i think they are failing internally (opening the electrical path in the battery/broken plate) AND the alternator which is original needs to be rebuilt/replaced.  I will follow up on this when i get the funds to do it all...

 

I will also check all grounds and connections for corrosion to the PDC and such to eliminate that.

 

since i had to dig for the info

 

2 Methods of Testing your Alternator for AC Noise

1. Remove the 140 amp alternator fuse in the PDC. Then unplug the field lead of the rear of the alternator. DO NOT remove the heavy charge lead. This was handled by removing the alternator fuse. Now go for test drive and see if the torque converter lockup issues occur. If no torque converter lockup issues then the alternator is at fault for AC noise issues. I highly suggest you verify by having the alternator bench tested and or do test #2 below. 

2. Remove the turbo intake tube. Now using a high-quality digital volt meter like Fluke or Extech. The DVM should have an AC scale capable of reading down to millivolts AC. If not you'll see measured AC volts in the range of 29 to 31 volts which is erred.

AC Noise Voltage levels

• Normal - 0.01 to 0.03 AC Volts 
• Marginal - 0.05 to 0.09 AC Volts (Some folks have reported random or odd behavior occurring at this low of voltage)
• Fail - 0.1 AC Volts and above. 

NOTE: W-T ground wire mod will make the AC noise much lower typical reading around 10mV AC to 20mV AC is Normal past about 40mV is a fail. Factory wiring is going to remain higher. Highly suggested doing the W-T ground wire mod. 

ill buy the rebuild kit for the alternator

 

 

Edited October 24, 20195 yr by CUMMINSDIESELPWR

Sometimes diodes don't solve the problem if you have a lot of use on alternator, brushes and armature will put out some ac noise also. Diodes is a good place to start along with WT mod.