I have a 2009 Dodge Ram 2500 with a 6.7 liter Cummins. When I start my truck the voltage gauge drops to around 10, the check gauges light comes on and the electronic throttle control warning light comes on. The voltage gauge remains around 10 and the ECT remains on while the engine is running, the gauge does not recover. When the truck is turned off and restarted the voltage gauge reads normal and the check gauges light and ECT warning light stay off. I took my truck to Dodge and they said it was the batteries and they both were changed, this did not fix the problem. I would appreciate any help with this problem. I would like to know where to go with this before I spend more money.

 

I had an intermittent issue with my voltage gauge dropping to zero while driving, then after I pushed accelerator hard, it would come back to normal. I changed by alternator, that fixed it. Might want to have it tested when it is in this condition. Could try to see what voltage at battery is when working properly. Then measure again when problem is occurring. If voltage is the same I would think it is not the alternator. If voltage is lower when issue is occurring, quite possible it is the alternator.

 

I just went through the same thing a couple months back. Ended up being the alternator.