Sorry for this being my first post; don't know where to post an intro though; and unfortunately after just getting this truck I'm already having odd problems with it. It is a 96 Ram 2500 flatbed with the cummins and 5speed.

The GEN light has come on 3 times now in the 10-12 times I've driven the truck, and after turning the truck off and restarting it the light will turn off. Normally the voltmeter shows 14 volts; but occasionally (such as tonight) it will show around 11-12 and drop down only to come fluctuate around. Also when this happens the gauges and headlights dim. I've already replaced both batteries and the terminal ends for both as well. There's been a few times where I've had to jump the truck already because after parking it it somehow just goes completely dead.

Here is a video I took on my cell phone of the voltmeter tonight. http://www.youtube.com/watch?v=Z8Yf-5LMrPY

The other issue it has is that the interior dome light does not work, even with a new bulb. I've checked the fuses and none are blown that I can tell.

Also when the truck is turned off the radio loses it's presets... It is a kenwood tape deck model that will be replaced with a cd player soon; although I'd rather fix the problem before I risk a new stereo in the truck.

Thanks everyone for your help and I look forward to spending more time on this board!
-Ryan

 

the headlights and gauges dimming and voltage flucuations are normal its the heating grid cycling on and off trying to get the air warm before it makes its way into the cylinders. however the batteries completly dying is not normal. lol i have no idea what that is...
hope this helps a little at least..
Jared

 

if this is happening after the truck is warmed up....often the gen light will come on then off again when the alternator brushes are on the way out...the brushes make intermittent contact, and therefore the alternator works sometimes and not other times. bearings don't usually last much longer than the brushes, so probably best to get rebuilt, or replace with a reman alternator.
the radio has a seperate wire and fuse for the memory...check the fuse.
the domelight problem could be poor connection between the bulb and lamp, or bad door switch, wiring, or fuse....check voltage along the circuit until you locate the problem...another check does the light come on with the light switch and not the door open?

 

Dome light never comes on no matter with door or light switch. Is there anything else is on the same circuit as the dome light?

No fuses are blown; for radio, interior lights, or anything else.

Truck has been driven 3 times today and needed jumped once after only sitting 2 hours. Parked overnight it started right up this morning though in 20 degree temp. Once the GEN light comes on it does NOT go off until the truck is turned off. After the truck was jumped it showed 15 volts all the time; while cold and after it had warmed up.

Someone please help me figure this out before I have to go spend a few hundred dollars at a auto electric shop. I can't drive a vehicle that I never know when it will need to be jumped (especially using this truck for lawn/landscape); and I don't want to replace an alternator if that isn't the problem.

Thanks again for the help all.

 

It sounds like you have at least 2 if not 3 or 4 separate problems , that can be hard for a mid level mechanic , with the right tools , so it could be a big issue for a do it your self , the best approach is to look at it as a possible 2-4 issues and fix one at a time , you may get lucky and get 1 fault to fix 2 out of 4 things , but focus on one at a time .
Do not replace anything on a guess , use testing to confirm bad parts , you can surpass the cost of some one els fixing it for you , with as little as one part .
I've seen some put in a battery , starter , alternator , give up take to a shop & find a bad connection or fuse .
Sounds like the last owner left you with what they did not want to fix .
Some of the problems may be self inflicted , things worked on , maybe putting in radio , & messed up some electrical .
You need to load test the batteries to see if they are good , if OK , then the dead after sitting is a drain , could be glove box lite not shutting off when closed , or diode bad in alt [ some of the newer alt tester will tell if diodes are bad ] .
If you find a bad alt , this is a good source for new [ not rebuilt ] also larger starter contacts & a few other things that are known to be issues with these truck .
http://www.fostertruck.com/dodge/default.htm

 

carry a dvm voltmeter with you (or better yet, just look at the meter on the dash). next time it doesn't start check battery voltage while trying to crank...might have the starter contacter problem...the extra voltage from boosting can arc across marginal contacts making it start. you can compare the voltage to normal crankiing voltage when it's working....should be more than 10.5-11V while cranking. a normal lfully charged battery should read around 12.6V

 

When not starting it shows less than 10 volts from the time I turn the key initially to on and just drops from there. As said with first post... both batteries are brand new, as in I bought them less than 2 weeks ago.

There is no interior lights... so no glove box light to drain the battery. It is an intermittent non start issue that as far as I can tell is completely random. Has nothing to do with temperature (it's been continually under 40 here since getting the truck); nothing to do with how long it's sat (had it not start when it was run 15 minutes earlier but yet it started after sitting overnight). I will try the auto parts places in town to check the alternator tomorrow..

 

As others said already, you most likely have multiple electrical problems.

Start by checking ALL of your fuses....in the cab AND under the hood.

Get the alternator tested ASAP. Pull it off and getting in bench tested is the BEST method to determine it's condition.

 

sounds like your grid heater is kicking on when its not supose to try disconeccting it if that solves your problem, check the battery temp sender i think this tells the grid heater to cycle,also check grid heater relays

 

You gotta get your hands dirty.
Take alt off and have it bench tested at friendly parts store. Now you know the charging system is working correctlly. It should be able to charge at rate of 14 volts or slightly higher into the batteries.
Check all terminals for corrosion and tightness.
To check for current draw; you need a 30 amp or more tester intially.
Hook amp meter between negative terminal and ground cable. Remember to remove other battery from circuit by disconnect. Disregard the intial surge and or arc. Remember to have everything turned off and don't open doors.
There should be less than one amp of current. If more, pull fuses till current draw subisdes. That may identify problem circuit.
That should keep you busy and give someone else chance to get involved.
Other solution: Take to friendly electric shop that deals with this every day and be done with it. Your sanity and increased productive will help pay for repairs.

 

sounds like an alternater to me! probably a diode going bad. had a 2000 in a few days ago had same symptoms. pulled alt off and had checked. bad diode on power up and then would come back. was spiking voltage into pcm.

 

update... truck has been acting completely normal other than the no interior lights. No gen light since last post... and the truck has started every time no problem. The radio is still wierd as well; but I've written that off as a faulty radio (it also only plays out of the left side speakers)