All,
new here but not to powerstrokes...
I have a 2017 6.7 psd f350 srw. Last Monday woke to a dead truck. Checked the voltage on the batteries and found them at 7v and 11v. The truck did sit from Friday evening to Monday morning. Put a charger on the batteries and got it started after a couple of hours. Checked the voltage off the alternator and found it at 14.3-14.6. Let it run for an hour and then drove to work. Went out and started it at lunch, started slow but still started. After work it was dead again. Got it jumped and drove home.
pulled the batteries and tried to charge them. One took a charge just fine the other did not. Took them to the local battery guy and he said they were fine to clean them and go with it....I didn’t believe him but I’ll try. Hooked them back up and found to have a parasitic draw. Ran it down to the seat heater module was pulling .4 amps constantly. Figured that could have an affect but not super convinced that that was the only problem. Got the batteries back in and charger. Let it sit over night and went out the next morning to find the weak battery totally dead. At this point I said screw it and went and got a new battery and put it in the truck. Hooked them not back up, checked voltage and tried to start. Got in and pushed the brake, pushed the start button, everything lights up but no start. Had the blind spot, cross traffic, hill start, warnings flash at me. It then said to press the brake to start but it did not start. I read about the battery management system so I **** everything off and locked it to sit overnight. Came out and same thing. Checked the obd codes and said the tcm lost communication....so other then towing it to the dealer does anyone have any suggestions??

Does anyone know how to reset the battery management system without taking it to a dealer?
Will the lost com with tcm percent start up?

thank you!
josh.

 

You have to replace both batteries together. Once one is bad, it kills the other. Now your new battery is probably toast too. Narrowing down the parasitic draw is a tough one, until you find it, disconnect both batteries between starts. Make sure all your positive cables and battery connections are clean and dielectric grease, do the same for all grounds. Then start searching for the draw(s)

 

When searching for the parasitic draw I put the tcm fuse back in the wrong spot, thankfully it was a not used spot #93. #94 is the tcm slot. Once I put it in the right spot the truck fired up just fine.
I did find the draw, it is the seat control module pulling .4 amps.

thank you!
josh.

 

Your still going to have to replace both batteries if I’m reading your post correctly you only replaced one, mismatched batteries will die pretty quickly, the weaker older of the two will slowly pull from t he newer one.

 

Josh, glad you got it sorted. I would recommend as Mike said, to change your other battery. The new one you had probably wasn't happy about being drawn down a bit but I don't think it's toast after one bad charge cycle. However, the old one will drag down the new one in time...

 

EDIT: Posted to the wrong thread.

 

Do you mind explaining how you went about finding the parasitic draw? I'm just curious.

 

Probably started pulling fuses while having an amp meter connected in series with the battery.

 

That was my guess but wanted to confirm....