How do I test my 1997 6.5 3500 dually charging system. The voltage gage is whoing battery voltage 12.7 or so. Can I test the alternator some how?

Here is what happened I think, truck sat for 2 months, new batters were dead, chagred with big NAPA charger for too long on 60 amps, the betteries were fully charged and truck worked great.

Now when I drive it the voltage gage is not reading 14 volts, only 12.xxxx, how do I test theelectrical system?

You can take the alt. off and take it to a parts store to have it tested. May also want to test the batteries, one of them could be bad as well......... I would also use a volt meter and check what the voltage is with the truck running and see how it compares to what the gauge says (maybe gauge is off).

You can take the alt. off and take it to a parts store to have it tested. May also want to test the batteries, one of them could be bad as well......... I would also use a volt meter and check what the voltage is with the truck running and see how it compares to what the gauge says (maybe gauge is off).

X2

ok, took one battery off and checked it, 11.55 and the other was also 11.53. Then connected them and checked, it was 14.15v while running. Darn thing and the gage was reading the same???

12.6 is a fully charged Batt.
14 - 14.5 when running says the charging system is working.

Sounds like the gauge is bad. Make sure your batteries hold their charge too. Charging them outside the vehicle is best. That way they aren't connected to any parasitic loads or each other. Sounds like the alternator is good.

Jake

sounds to me like removing and testing cleaned up the connections ... grounds being the most important issue with our trucks

i had this same problem not too long ago. i ended up replacing all battery cables since i found that some of them had green corrosion going into the rubber sheath. figured the cable was not conducting very good so decided to replace all. charging system works with no problems now

ok, took one battery off and checked it, 11.55 and the other was also 11.53. Then connected them and checked, it was 14.15v while running. Darn thing and the gage was reading the same???

Just checked voltage, or load tested? They need to be load tested, individually, If one is bad, replace the set.

Thanks everyone, I just put new walmart natteries in it. I have noticed that the clock time stays on in this truck, What is that, couold that be draining the betteries? I think the radio light/time should go off after a while.

ive also been told the dome light switches in the door frames (little buttons) could also be sucking power over time

OK, I see that sometimes, well, everytime after I start the truck cold, the wait to start light comes back on and the volts go way down. This happens 3 time most often.

Then when driving, the volts go down like something is using all the voltage. A little like the glowplugs.

Is there a way to test the glow plug circuit to see if it is inadvertantly comming on?

Has anybody seen this before, the volt gage sometimes reads 10-14 volts while driving.

Those are usually bad cables, connections and grounds somewhere.

whatching I am having the same damn problem

OK, I see that sometimes, well, everytime after I start the truck cold, the wait to start light comes back on and the volts go way down. This happens 3 time most often.

Then when driving, the volts go down like something is using all the voltage. A little like the glowplugs.

Is there a way to test the glow plug circuit to see if it is inadvertantly comming on?

Has anybody seen this before, the volt gage sometimes reads 10-14 volts while driving.

the glows cycling while driving is to help heat the cylinders until enough heat is generated it is normal .. unless you sit there parked until it builds enough heat

i can sit for 6+ hours at the drive in movies with my stereo louder then hell and still start no issue. that being said the thought of the clock radio draining enough juice to prevent the truck from starting is a little crazy....

PS... my stereo is listed in my sig ... if 1300+ watts wont drain it

This truck drained the batteries after sitting for 2 months. Thought it might be the radio but after recharging, it doesn't seem to charge on tehroad correctly. I'll check all the connections. It only had 60k on it and in the build sheet it had the alt replaced at 18k. Maybe this issue has been presistant.

02/09/2000 163462 # J4100 - GENERATOR REPLACEMENT 18664 miles

Checked the connections, they were questionable!!! charged both batteries when theyu were disconected.

ok, recharged the batteries, 12.6v and 12.6v measured alone or on each. Betteries fully charged.
Connected batteries back up and turned teh key on.
The wait to start light would come on, then off, then on, like a blinker.
That doesn't seem right.
Thanks for any and all help

I had this problem when I put a new cable on. I initially did not swap the lead puck from the old to new cable. I put the puck in and made sure both leads connected well when bolted to the + battery lead.

I can tell it is getting power from both batteries. It turns over fast and everything is fast. I can recheck teh terminals per you post and let you know.

OK, fixed all the connections. When I first start the truck after the batteries have been disconnected, the glowplug system blinks like a blinker on first start only. The next starts glow plug system cycles at normal rate.

The charging system is ok while the truck is cold, after driving it for 20 minutes the volt meter reads 13.9 volts. It measures 14.05 at the batteries. On first start after the glowplug system stops cycling, it charges at 14.4 volts.

Why would the system seem to be lower after the truck worms up?

ok, I found the current drain. When the heater is on max I see I loose volts, and when the lights are on, I loose volts. So it seems that the altinator can not handle the current draw. Can that be? It Said that it came with a 100 amp altinator. From build sheet:
K60 - ALTERNATOR 100 AMP << they replaced it but should of been the same one << the dealer did the change at 18k miles
Is it possible that the light and heater/AC take all the current this altinator puts out?

Thanks
Lief

Took the new (6 months old) batteries into have tested, they said their were dead or bad cells in each battery. The warrenty was still good so they gave me 2 new ones with reciepts, can't been walmart.
The issue may be that I have a charger that may cause issues, it was set on 60 amps and maybe left on too long. Although they batteries should not of discharged in teh first place.
I'll post if the voltage still drops when the heater and lights are put on.

Later dudes!!

Checked the connections, they were questionable!!! charged both batteries when theyu were disconected.

ok, recharged the batteries, 12.6v and 12.6v measured alone or on each. Betteries fully charged.
Connected batteries back up and turned teh key on.
The wait to start light would come on, then off, then on, like a blinker.
That doesn't seem right.
Thanks for any and all help

12.8 Volt is fully charged battery. 12.6 Volt needs a charge. Any less and the battery is bad or being deep cycled. I think you have a small current drain.

13.5V or higher and the alternator is good.

Disconnect both battery grounds. Put an amp meter between one battery and ground with everything off. The current draw should settle down to like 0.09 Amps or less. (Don’t have exact spec.) Look for a stuck on glove compartment light etc if it is higher. Pull fuses one by one (Then put it back) to see what is drawing too much current.

Glow Plug controller. Is it still blinking like a blinker? Connections on it clean and tight? Check the factory ground for the controller. Check the ground from the engine to the frame. I had one controller fail and it would do this rapid blinking. A capacitor broke the solder joints inside and would vibrate with the solenoid kicking in make contact and shut off, lose contact on shut off and kick the controller back on. Replace the controller if the connections check out. DO NOT LET THE CONTROLLER DO THIS RAPID CYCLE AT ALL!!! :eek: It will burn out the glow plugs! Been there done that... (The controller is loosing track of how hot things are by resetting it’s timer from low voltage or other internal failure.)

You should test each glow plug for resistance just in case it has already taken some out.