Regulator periodically overcharging
 

I am new to this forum and a new member. I sure hope someone can help me with the issue that I am having. I have a 2000 RAM 1 ton dually with the 5.9 turbo diesel engine. Occasionally as I am driving my amp gauge will suddenly peg out at 18 amps. I can pull over to the side of the road and just idle down for about 10 seconds and the amps will go back to normal. I may drive 10 miles or a 100 miles and it will do it again. I have changed the alternator out twice, cleaned the battery terminals, and reset the computer by unhooking both batteries for over an hour. The truck seems to over charge less if I drive 60 mph or less than if I drive 65 or faster. This problem just started about a month ago. I have at times driven it over 350 miles on a trip with no problem at all. The next time I start the engine it may jump up to 18 amps in the first 20 miles. It may be my imagination but it seems like once it pegs out at 18 amps it will continue to do so every 5 to 10 miles until I turn the engine off and restart. I will appreciate any and all suggestions. Thanks in advance.

A common issue is wires chafing where they contact the AC line below the alternator near the oil filter.

(moved to proper forum to help you get more answers)

Thank you for moving me. I will check the wires you mentioned.

the way I understand it all charge controlling is by the computer message to the alternator,not the alternator

Yes, that is correct. No internal regulator in the alternator. The regulator is in the PCM. It may be that I need a new PCM but I am hoping through suggestions that I can find that it is something else less expensive.

question you say goes up to 18 amp. do you mean 18 volts?? if so I would put a meter in the cigarette outlet and see if it reads the same as the battery voltage if so go for a drive and monitor the voltage in the truck and see if the battery voltage matches the gage reading, maybe just a bad gage or inaccurate one. and pcm maybe ok. Just a thought

Yes, 18 volts. I will try your suggestion. Thanks

As a rule, if the PCM is the issue it becomes a full time problem, not intermittent.

Along with other things, don't forget the battery temp sensor, when it is cold out, it charges more. If for some reason the temp sensor is reading very cold, it could charge high. I am not sure what resistance reading is indicated low temp though.

I have replaced both batteries in the truck and I have cleaned all grounds. The batteries were from NAPA and new in Feb. of this year but both showed weak when NAPA tested them so they replaced both at no charge yesterday. I also bought a volt meter so I can monitor the voltage as I am driving. I am going to see what happens from here. Other than this, I don't know and I guess I will have to start consider the PCM. I replaced the alternator a week ago. I don't know what else to do!!

As I am driving what should the correct voltage be as I am going down the road. 14.6??

Runnning down the road voltage could be from 13.8v. to 14.4v. 14.6 is not too high though as the volt meter could be off a touch.

Check the positive cable between batteries. It may have corrosion in cable . Look for swelling or green stuff on wiring. Also the two gray connectors near right battery.