Help please with charging system issue

[steve gravelle]

Vehicle 2008 Ram 2500 6.7
Issue- sudden no charging
Symptoms- stopped for fuel 80 miles east of Little Rock, heading west
Attempted to restart, very slow cranking, them cranked OK and started
Check gauges light on, voltmeter reading in 11-12 v. range, throttle light on
Swapped fuses in panelu nder hood for PCM, no change.
Drove to little Rock, voltage dropped about 1 volt but all other gauges are normal, all other systems functioning normally.
Has 2 almost new Interstate batteries, tested OK 2 months ago, 115K miles.
Is there a typical failure that happens?
I believe charging is run through PCM.
Any help or guesses much appreciated.
Cell 303 250 2176
I realize our forum is not to fix tow units, but we have lots of knowledge here, many drive Dodge/Ram!

 

[Tow'd hauler]

When running you should be charging 13 to 13.5 volts if not its prob. the alternator

 

[steve gravelle]

My thought too, but I have worked in auto for 40 plus years, and on our trucks it can be the PCM and a couple of other possibilities besides the alternator, I hope to find a good independent shop here in Little Rock tomorrow, but most of the good shops are 5 days a week. Dealers make me nervous (like boats)! Thanks for jumping in!

 

[Retread68]

I'm not driving a Ram, but as Tow'd hauler said, the alternator should be putting out between 13 to 14 volts. If it is and you have checked the fuses, it quite possibly is the PCM since best I recall the voltage regulator is part of the PCM. I would check the battery cables - being tight on posts, check for weak spots in wire between alt-to-battery, check for dry cells in battery. If none of those and the alternator is putting out approx 13.5 v then I would be thinking PCM.
Sorry you're having the issue.

 

[Cate&Rob]

Hey Steve,

My first guess would be same as Tow'd hauler . . . alternator problem.
I would put a voltmeter directly across the battery terminals with engine off and then again with engine running. There should be a couple of volts difference (regardless of the absolute accuracy of the reading).

Second guess would be a failed battery (less likely with two, but a bad one can take down the other).
Engine off, turn on the headlights and measure voltage before and after. Voltage should drop a little but not too much with headlight load. If it drops a few volts, this is likely a bad battery.

Rob

 

[steve gravelle]

Rob, good stuff! My Fluke will get a workout in the AM!

 

[orbiker]

Just go to a place that sells car batteries.

Have them check the battery. They will do a load test and then you will know what needs to be replaced.

 

[Cate&Rob]

Rob, good stuff! My Fluke will get a workout in the AM!

Since you have a Fluke, you get to know the absolutely correct values
One additional thought . . . if it is looking like "battery" rather than "alternator", it is likely only one battery and you can disconnect that one.

Good Luck !
Rob

 

[steve gravelle]

Resolution, almost!
In Little Rock, called NAPA store 8 AM Saturday for recommendation of shop. They said a Goodyear store on Geyer Road, which I called and Robert, the manager said bring it in, we can find the problem. They got me right in despite being pretty busy, after a few minutes Robert brought me out and showed me voltage readings on his Snap-on Solus scanner, 14.4 volts output on the alternator, batteries at 12.2. Dash gauge still very low, around 10 or 11 volts. His thoughts were wiring issue or PCM, didn't have a decent wiring diagram for my truck. He had quoted $49.95 for testing, would not charge me anything, "we did not fix your problem". I gave him $5.00, thanked him a lot! He called Ram dealer (Steve Landry), their service dept. was open until 3 PM. I got there and was told they would get it figured out. About an hour later, much testing, I was told one battery had shorted cell, which possibly create feedback to cause dash gauge issues. Reprogrammed, cleaned questionable battery connections and offered me their battery at $125.00 (decent price), I declined because I can get a direct Interstate replacement N/C at their Dallas store, where we will be tomorrow. I was treated very well by both places, I believe it was because I was reasonable and appreciative of their efforts. Thank you all for your help and concern!

 

[Cate&Rob]

Steve,
Great to hear that you have encountered fair and helpful service providers and have this sorted out.
I can't count the number of times I have seen one bad cell in one battery, confuse the charging for an entire multi battery system.
Rob

 

[steve gravelle]

Update on this issue! All went well as we traveled to Dallas. I went to Interstate battery store in Rockwall, TX, where I had one battery replaced N/C under warranty April 2015. Manager took his official tester out to truck, disconnected one battery negative cable, ran through multiple tests where both batteries tested good. Since then, highway miles to Mesa, AZ, Tombstone, and back to Texas, now at Buckhorn Lake in Kerrville, has been flawless. We hope this continues. We appreciate everyone's input and concern.

 

[Handyman]

I had an interstate battery crap out on me 3 months after I bought them. Truck had same symptoms as yours... Had a set of jumper cables and it would fire right up when jumped... Glad you got it figured out

 

[steve gravelle]

My 40 plus years in automotive give me knowledge to express the opinion that Interstate batteries have a higher failure rate now than they did then. The compensating factor is that there are lots of dealers everywhere! Many of us know that they do not build their own batteries, and that now some of them are built in the "state" south of Texas!

 

[WhittleBurner]

sears die hards are just as bad as interstates. In fact seara get their battery's from interstate. Go to a sears auto center and they will have a room just for the battery's that get returned.