I posted this in the 2nd gen forum before I noticed the one for Cummins Diesel ...

This one's got me stumped, and I need some advice.

My truck: '95 DC3500, turning 150,000 miles this week (hopefully)
Pertinent components I've replaced within last 2 years: Both batteries, fuel shutoff solenoid, starter

Symptoms: Very hard to turn over, like the batteries are almost dead. Once it does actually start, it runs fine. Measured voltage (at battery) when truck is running is nearly 14, when I shut it off the voltage trickles down to about 12.95 and stays there for at least 5 minutes. The next morning the voltage is at 12.6. I hop in, turn the key to warm up the plugs, then fire it up and again it's almost like the batteries were dead. At this point I'm _nearly_ sure it's not the alternator because it seems to be generating the voltage it needs to. I took the batteries up to AutoZone and they tested fine, which I figured because the headlights don't dim when the truck is turned off. So then I figure maybe there's corrosion somewhere in the battery cables, so yesterday I replaced both negative-terminal-to-ground cables. I replaced the cable that connects the positive terminals between the two batteries. I didn't replace the positive-to-starter cable, but I did replace the terminal it connects to and I checked the connection at the starter and it looks as new as it did when I replaced the starter last year.

So, what am I missing? I did notice in the several times I've started it since this began happening that the volt meter in the dash doesn't always show the same reading. Sometimes it's just over 14v, sometimes it's right at 14v, and a couple of times it's been slightly under 14v. From what I can tell, though, the charging system and batteries are doing what they're supposed to. It just seems like maybe something's loading the system when I try to fire it up and I just can't figure out what.

Any input is _greatly_ appreciated.

-Z

 

I'd suspect the starter. Sometimes new ones are bad. Take it and get it tested.

 

thanks for the suggestion. i was sort of thinking the same thing, so i ran it up and had the starter as well as the alternator tested. they both tested good, however i noticed something during the alternator test. the tester showed that the alternator is putting out 97 Amps, however i see this baby's supposed to have a 120 Amp alternator so i'm wondering if it's not putting a high enough charge on the batteries for them to take that initial deep current draw. thoughts?

 

that could be the Alt. in your last post
Did you by chance check the power supply at the starter maybe bad cables to the starter. It maybe in the middle of the cable where you can't see it but the end where you replaced is ok

 

that's a good point. i haven't checked the voltage at the starter. i know that the upper end where it connects to the battery terminal looks good, as does the other end down at the starter, but that doesn't mean that everything in between is good. that would be easy enough to test with creative use of a jumper cable and disconnecting the cable that's there now. i'd think, though (and please correct me if i'm wrong) that the starter test this evening would have picked up a problem even if it was in the cabling ..? i noticed, though, that when i click the key over to warm the plugs and then hit it full on to start her up that it looks like (according to the dash voltmeter) the voltage dips way down, like possibly 10 volts or so. i haven't double checked this with my hand held multimeter yet but it definitely dips way down into the black on the left side. it was suggested to me that maybe i have a battery in early failure that the tests weren't picking up, and that i should completely disconnect the terminals from the battery and measure their voltage independently this evening and then measure again in the morning and see if one is significantly less than the other. tonight they both (duralast gold 27-dlg) measured 12.93v after i disconnected all terminals, i'll see how they look in the morning. i'll try bypassing the terminal-to-starter cable with a jumper cable as well and see if that makes a difference. thanks!

 

one more thing to check
the exciter wire to the starter. I do not know how Dodge has that wire set up
but on the forklifts that i work on that wire from the key isn't direct it goes to a starter soliniod (like found on older fords) but that is wired in by customer (Taylor Machine works) Dodge may do the same I am not sure Since I have not yet worked on my truck that much I am not sure how the wiring is. So this post I'm just tossing Ideas at you. But it maybe a good thing to check when all else fails
on the battery cable do a condutuity <---misspelled test to see if the current is ok
Safety advise disconnect the battery cable at both ends just in case your computerized vehicle but being a good old 95 maybe not

 

i'll take a look at that. i checked both batteries this morning after leaving them disconnected last night, they're both measuring 12.74 so i think i've eliminated them as being the problem.

 

I would do a voltage drop test on the positive cable to starter. You shouldnt see more than a few tenths of a drop in voltage. Or do a resistance check on the cable to check for any unnecessary resistance. btw way a fully charged battery should read between 12.68 to 12.75v

 

followup:

it was the starter. when they tested it and it passed, they were using some handheld tester with the starter still mounted up. after testing/replacing just about everything else i pulled the starter out. it turns out that something in engaging the gear was dragging (friction) and pulling more power than it should have to actually kick that shaft out. the solenoid was engaging fine, and i guess that's what was throwing me off. the starter failures i've had before (with this truck, and other vehicles) has been the usual 'click click click' problem where it would eventually kick the shaft out. it just really seemed like the batteries to me, and everyone that heard it told me that it sounded like one or both of my batteries were going bad but it turns out the batts were fine, the starter was just pulling a lot trying to engage the gears.

fyi and thanks for the suggestions,

-Z

 

Good I'm glad you figured it out
PIZZO