Well I went out this morning to go hunting. Truck was dead. Jumped it and was letting it warm up. Went to leave as soon as I pulled out of the driveway I got a warning light "check gauges" and my battery gauge went to 0. Was going down the road and got another warning came on the radio saying battery charge was too low, system will shut down in 3 mins. Turned right around and coasted in before my truck died.

Took the alternator and both Optimas out took them to get tested. All came back good. The batteries tested good, but w/ low charge. Had them leave it on a trickle charge. Put alternator back in. Got them back later and installed them. Started right up. Passenger side battery was @ 18.8 volts and dropping and other was @ 11.8 volts while idling. Left the truck run for about 1/2 hour went out shut it off and and the passenger side was hot and was steaming. I hurried up and checked the volts there down around 14.2 volts

What could be wrong? Batteries? Alternator? Anything I'm not thinking about? Please help me out. I'm lost.

 

Possible major draw on the system. Maybe something with the grid heater ???
Pull all cables. Then hook up negative. As you hook up positive, look for larger than normal spark. Can also check with a voltmeter with positive wire OFF and test between positive post and positive wire with negative hooked up.

 

One more thing . Check positive wire and see if it's possibly getting grounded out. It must be something with no fuse.

 

I don't understand how the passenger battery could be at 18.8V when both batts are connected on the positive side. It sounds almost like a cell-liner in that battery has broken, and two of the charging plates have come in contact.

 

Hmmmm., well he did say that he took that reading while the engine was running. I dunno.

 

Check the main fuse in the PDC (power distribution center).

 

The charging system in the 3rd gens is not cabled that great and the passenger side battery boiling over or even blowing up has been seen before.


This thread explains a similar situation and JBody's post explains the charging system theory of operation and what can happen.

https://www.dieseltruckresource.com/...t=battery+blew


As Jbody explains it, the ECM controls the alternator output and monitors the driver side battery voltage to do this.
But the alternator output is connected to the passenger side battery & then loops back to the driver side.

If there is a bad connection or blown fusible link anywhere in the cabling, the voltage at the driver side battery will show low, which the ECM monitors and signals the alternator to increase output which goes to the passenger battery. Then the passenger battery is being totally overcharged.

Jbody's suggestion to "T" the alternator's output to both batteries is a good one.

All credit goes to Jbody for sharing this excellent info.

...Joe