p2509 won't clear, and extended cranking time, low volts on dash

[tomj]

03 ram 5.9 4x4 w only 82k and never a problem. Battery was very low after not driving it for 2 weeks, barely started then CEL came on code p2509. Now takes 3 seconds to start, every time, used to be instant. Replaced batteries, code won't clear, voltmeter on dash stays at 11v until I drive for a bit even though a fluke meter on the terminals says 14.6 at the same time. grid heaters seem to be functioning because If I put a voltmeter in the cigar lighter I see voltage go down when I hear the grid solenoids click. I was not able to see if the heater is actually warming up, did not have a chance and the next day it got warm and it doesn't seem like they are coming on (truck may have been a bit warm) Grid heater wiring looks perfect, I redid all the grounds for both batteries. I know the hard start caused this problem- maybe corrupted the ecu? Us a reflash the solution? I know there is a reflash tsb (18-001-07) but the TSB is not super clear if it is for 06-07 or anything pre 07. I've seen a ton of posts around the web of people throwing money at this problem with it not getting resolved (batteries, alternator, wiring harnesses, ECM, etc), so I'm looking for someone who found the actual problem.

 

[DavidC]

First thing is to seperate batteries and load test

 

[tomj]

The batteries are brand new, I replaced them right after the problem appeared.

 

[AEdelheit]

I would check the resistance of the crossover cable, they are prone to corrosion, the starter is powered off the driver battery while the alternator charges the passenger battery .

 

[GCroyle]

1. Wiring schematic of power distribution.
2. Good DVOM. Extra credit if you bought the DC amp clamp on meter version.
3. Follow the path of 12V.
4. A bit of luck.
5. Pencil for item 1. notes.

Not trying to be smart head cause I ain't.

Yup, I might be in left field or way south.

Good luck.

 

[tomj]

The cables are perfect, just tested the crossover anyway and its fine, .1 Ohms, batteries are both at 12.53v. My clamp ammeter is not working, of course... I'm going to follow all of the power for the ECM but I'm not optimistic

 

[Ozymandias]

You can not test the crossover cable with an Ohm meter. To test it you need to measure voltage drop from left to right battery while cranking the engine.

12.53 is not fully charged battery but not to bad also.

 

[mfurrh55]

I had that code , battery on passenger side got so hot I thought it would explode, changed battery and it still got warm, drivers side was cold, I replaced both batteries and replaced the crossover cable and put military terminals on batteries.... seems to have cured my problem, I ordered a 2/0 cable , it came with terminal rings on each end and 84" long, paid like 38.00 for the cable, pm me and I can direct you to the place I bought it, or go look up my post on it

 

[tomj]

Voltage differential between batteries is only around .1v when cranking, cables are pristine on both ends and over their length. Battery voltage shows 14.6 on my DVM as soon as it starts even as dash meter indicates around 11-13v, until it runs for a few minutes. then the dash meter corrects to actual voltage. The resting voltage of 12.53 is due to repeated testing probably and not much real run time for charging as I'm trying to figure out what's going on.

 

[DavidC]

The dash gauge is a little slow like it's buffered so I don't think I would be concerned with that. Mine has been like that since purchased.

 

[Ozymandias]

Did you check the battery temp sensor below drivers side battery?
If that is bad it also shows low voltage on the dash gauge but actually charges normal on an external volt meter.

 

[Ozymandias]

And disconnect as a test the feed wires to the grid heater relays, sometimes we have seen that they turn bad and pull to much amps leading to the 2509.

 

[AEdelheit]

Did you check the battery temp sensor below drivers side battery?
If that is bad it also shows low voltage on the dash gauge but actually charges normal on an external volt meter.

When I bought my truck the battery temp sensor was broken and it was a few years before I replaced it, there was no difference is charging voltage, gauge , no codes or anything so maybe something is different for 06 but there was no change after I replaced it.

 

[tomj]

I really didn't look very closely at any potential delayed behavior of the voltmeter until now, its possible it may have been like that all along. Will check that temp sensor; I read that in low temps it directs the alternator to charge at a higher voltage, or maybe a higher duty cycle. I've also ready that the ECM needs to see the voltage drop resulting from turning on the grid heaters & if not it would assume 1 or both are bad. What the result of that would be I don't know. Codes? extended crank time? Of course now it has warmed up here quite a bit over the last few days so the grid heaters aren't coming on anyway. You wouldn't know there was anything wrong if the CEL wasn't on or if it didn't take an extra second or 2 to start. I'm thinking it may be delaying the first shot of fuel a bit because it seems like as soon as the engine catches the rpms are a little slow for a second where as before it would start instantly at full idle rpm. I'm debating if I should bring this in for service. There is an independent shop here that "specializes" in diesel rams but they never heard of this issue, yet its all over the internet. Rather not pay $95/hr for someone else to learn on the job how to fix what seems like it might be a common problem that another shop may know how to easily fix. I almost always do my own work, the last time I didn't (injector replacement on an Isuzu FVR) the tech didn't torque the injectors, the injector sleeves leaked after 130 mi and I had a $900 tow bill, and they didn't put the o ring on the oil drain plug. Dinner plate sized puddle under the truck in my driveway when I got it back. luckily I was able to back out the plug and stretch a new one over the head and screw it back in. I swore never again after that debacle.

 

[Ozymandias]

Yeah, seems every MY has it's own ideas. When I disconnected the Temp Sensor it did as I've written above.

But also, my voltmeter takes a second or two after start, as the field is controlled by the ECM it makes sense that it first checks all systems and then start charging.

And yes, Temp is very important, in very cod environment you see up to 15.2V of charging and on the opposite site in very hot as food just 14V.