Truck won't start
 

I just disconnected both negative battery terminal on my 2008 Ram 3500 (Cummins 6.7)

The batteries are both good (just over 12 volts). I tried the IOD fuse (pulled for 10 seconds) but that didnt work. No fuses are blown.

Any ideas?

If it's an auto, try starting it in neutral. (not sure if the 08s will let you.) It may not be in park fully.

Thanks. I tried that just now - no luck.

My windows are stuck down too (happened yesterday) so I have a tow to the dealer coming. I'll write back with what happened.

Thanks for the help.

Sorry that didn't work, easiest thing first. You said the windows are stuck down as well? That is weird...

FWIW...

I knew of a 6.7 that had similar issues that you do on your truck.. call it crazy, but it wound up being a bad battery cable from the starter to the battery.. it was not making the right contact and wouldn't engage the starter at all....

It sounds bizarre, but a new set of battery cables fixed this thing.. and it didn't even have 60K miles on it when it was fixed...

I had it towed to the dealer since the windows were stuck down, it was due for the N49 recall and as well as a turbo cleaning that I finally got Chrysler to pay for.

The dealer said the ECM is dead - that it won't communicate - he couldn't elaborate so I'm going to talk to the technician today. He did however know the cost of a new ECM which he was confident I need ($2400 just for the part).

In the event I need a new one, has anyone ever replaced theirs?

You cannot test a battery with a volt meter. The fact that it reads 12 volts tells you nothing. They must be tested under a load to determint if they are putting out enough amperage. Are they the original batteries? If so, they are highly suspect. Hate to see you spend that much money for something you don't need. Were you able to pull any codes? Did any of the lights come on?

I just spoke to the service tech. He said at least one battery is bad. But I tried jumping it just to see what would happen and it didnt start - so I don't think it's just the batteries - plus the tech said the ECM lost its memory He also said he can't upload a new flash to it, that it has to be replaced.

I wonder if these trucks behave similar to the Aspen's? When the battery died on my wife's Aspen I couldn't jump it with the truck. I put a new battery in and she fired right up without hesitation. It could be possible the ecm is inhibiting any communication until it detects good batteries. Think of it as a way the computer protects itself to keep technicians from programming it w/ a weak battery then the battery dies in the middle of an upload corrupting the computer.

I'd say replace both batteries first since one is bad. Then go from there.

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Also, I find it hard to believe the ecm suddenly "lost" it's memory. There are companies that repair and/or program them on a test bench w/out issue and send back to you for immediate installation. It just sounds like they are after your money.

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:agree: Replace BOTH batteries and see what happens. You are going to need them anyway.

I am headed to the dealership now with two new batteries. I think/hope the truck is still stuck in their parking lot so I can do the batteries myself.

Thanks for the help with this.

Any recommendations on which companies to send the ECM to?

At dealer now. Both batteries are replaced. Still no start.

I plugged in autoenginuity to see if could pull any codes and it won't connect.

Are the battery cable ends clean and corrosion free? Also be sure to check all of the ground connections and each connection is tight.

Yes. Everything is powered. The truck is not dead. The service tech used a WiTech scan tool and it showed the PCM/ECM as offline.